Prenatal maternal immune activation has been used to test the neurodevelopmental hypothesis of schizophrenia. Most of the data are in mouse models; far less is available for rats. We previously showed that maternal weight change in response to the immune activator polyinosinic-polycytidylic (Poly IC) in rats differentially affects offspring. Therefore, we treated gravid Harlan Sprague-Dawley rats i.p. on embryonic day 14 with 8 mg/kg of Poly IC or Saline. The Poly IC group was divided into those that lost or gained the least weight, Poly IC (L), versus those that gained the most weight, Poly IC (H), following treatment. The study design controlled for litter size, litter sampling, sex distribution, and test experience. We found no effects of Poly IC on elevated zero-maze, open-field activity, object burying, light-dark test, straight channel swimming, Morris water maze spatial acquisition, reversal, or shift navigation or spatial working or reference memory, or conditioned contextual or cued fear or latent inhibition. The Poly IC (H) group showed a significant decrease in the rate of route-based learning when visible cues unavailable in the Cincinnati water maze and reduced prepulse inhibition of acoustic startle in females, but not males. The Poly IC (L) group exhibited altered responses to acute pharmacological challenges: exaggerated hyperactivity in response to (+)-amphetamine and an attenuated hyperactivity in response to MK-801. This model did not exhibit the cognitive, acoustic startle, or latent inhibition deficits reported in Poly IC-treated rats, but showed changes in response to drugs acting on neurotransmitter systems implicated in the pathophysiology of schizophrenia (dopaminergic hyperfunction and glutamatergic hypofunction).
Polyinosinic-polycytidylic acid; Poly IC; (+)-amphetamine-induced locomotor activity; prenatal immune activation; MK-801-induced locomotor activity; Morris water maze; Cincinnati water maze; rat; elevated zero-maze; marble burying; light-dark test; conditioned fear; latent inhibition; autism spectrum disorder
Introduction. Wernicke's encephalopathy is a well-described syndrome characterized by the classic triad of confusion, ataxia, and ophthalmoplegia. Wernicke's encephalopathy results from thiamine (vitamin B1) deficiency. Common causes include alcoholism and gastric disorders. Wernicke's has been described in patients with acquired immune deficiency syndrome (AIDS); however, given these patients' immunosuppressed state, the diagnosis of Wernicke's encephalopathy is not apparent. Case Presentation. A 31-year-old previously healthy male presented to the ER complaining of progressive dyspnea. Workup revealed HIV/AIDS and PCP pneumonia. He was treated and improved. On day 14 he became confused and developed nystagmus and ataxia. Considering his immunocompromised state, infectious and neoplastic etiologies topped the differential diagnosis. CT head was negative. Lumbar puncture was unremarkable. Brain MRI revealed increased T2 signal in the medial thalamus bilaterally. Intravenous thiamine was administered resulting in resolution of symptoms. Discussion. The classic triad of Wernicke's encephalopathy occurs in 10% of cases. When immunosuppressed patients develop acute neurologic symptoms infectious or neoplastic etiologies must be excluded. However, given the relative safety of thiamine supplementation, there should be a low threshold for initiating therapy in order to reverse the symptoms and prevent progression to Korsakoff dementia, which is permanent.
Objective. To examine long-term changes in physical function and body composition in coronary artery disease (CAD) patients participating in ongoing community-based cardiac rehabilitation (CR). Design. Thirty-four individuals (69.7 ± 8.2 years; 79% men) participated in this longitudinal observational study. Baseline and follow-up assessments included incremental shuttle walk, short physical performance battery, handgrip strength, chair stands, body composition, last year physical activity, and CR attendance. Results. Participants attended 38.5 ± 30.3% sessions during 1.6 ± 0.2 year followup. A significant increase in 30-second chair stands (17.0 ± 4.7 to 19.6 ± 6.4, P < 0.001), body weight (75.8 ± 11.1 to 77.2 ± 12.1 kg, P = 0.001), and body fat (27.0 ± 9.5 to 29.1 ± 9.6%, P < 0.001) and a decline in handgrip strength (36.4 ± 9.4 to 33.0 ± 10.6 kg·f, P < 0.001) and muscle mass (40.8 ± 5.6 to 39.3 ± 5.8%, P < 0.001) were observed during followup. There was no significant change in shuttle walk duration. CR attendance was not correlated to observed changes. Conclusions. Elderly CAD patients participating in a maintenance CR program improve lower-body muscle strength but experience a decline in handgrip strength and unfavourable changes in body composition, irrespective of CR attendance.
Organisms using oxygen for aerobic respiration require antioxidants to balance the production of reaction oxygen species during metabolic processes. Various species — including humans and other primates—suffer mutations in the GULO gene encoding L-gulono-γ-lactone oxidase; GULO is the rate-limiting enzyme in the biosynthesis of ascorbate, an important cellular antioxidant. Animals lacking the ability to synthesize vitamin C develop scurvy without dietary supplementation. The Gulo(−/−) knockout mouse requires oral supplemental vitamin C; without this supplementation the animal dies with a scorbutic condition within several weeks. Vitamin C is known to be most abundant in the brain, where it is believed to play important roles in neuroprotection, neurotransmission, and neuromodulation. We therefore hypothesized that ascorbate deficiency in Gulo(−/−) knockout mice might lead to an abnormal behavioral phenotype. We established the amount of ascorbate in the drinking water (220 ppm) necessary for generating a chronic low-ascorbate status in the brain, yet clinically the mice appeared healthy throughout 100 days postpartum at which time all behavioral-phenotyping tests were completed. Compared with Gulo(+/+) wild-type littermates, ascorbate-deficient Gulo(−/−) mice were found to be less active in moving in their environment; when in water, these mice swam more slowly in some tests, consistent with a mild motor deficit. We found no evidence of cognitive, anxiety, or sensorimotor-gating problems. Despite being less active, Gulo(−/−) mice exhibited exaggerated hyperactivity to the dopaminergic agonist methamphetamine. The subnormal movement, combined with hypersensitivity to a dopamine agonist, point to developmental ascorbate deficiency causing long-term striatal dysfunction.
acoustic startle response; ascorbic acid; elevated zero maze; L-gulono-γ-lactone oxidase; locomotor activity; methamphetamine challenge; Morris water maze; novel object recognition; oxidative stress in brain; vitamin C
Enhanced oxidative stress or deficient oxidative stress response in the brain is associated with neurodegenerative disorders and behavioral abnormalities. Previously we generated a knockout mouse line lacking the gene encoding γ-glutamylcysteine ligase modifier subunit (GCLM). Gclm(−/−) knockout (KO) mice are viable and fertile, yet exhibit only 9–35% of wild-type levels of reduced glutathione (GSH) in tissues, making them a useful model for chronic GSH depletion. Having the global absence of this gene, KO mice—from the time of conception and throughout postnatal life—experience chronic oxidative stress in all tissues, including brain. Between postnatal day (P) 60 and P100, we carried out behavioral phenotyping tests in adults, comparing male and female Gclm(−/−) with Gclm(+/+) wild-type (WT) littermates. Compared with WT, KO mice exhibited: subnormal anxiety in the elevated zero maze; normal overall exploratory open-field activity, but slightly more activity in the peripheral zones; normal acoustic startle and prepulse inhibition reactions; normal novel object recognition with increased time attending to the stimulus objects; slightly reduced latencies to reach a random marked platform in the Morris water maze; normal spatial learning and memory in multiple phases of the Morris water maze; and significantly greater hyperactivity in response to methamphetamine in the open field. These findings are in general agreement with two prior studies on these mice and suggest that the brain is remarkably resilient to lowered GSH levels, implying significant reserve capacity to regulate reactivity oxygen species—but with regional differences such that anxiety and stimulated locomotor control brain regions might be more vulnerable.
acoustic startle response; elevated zero maze; GSH; reduced glutathione; locomotor activity; Morris water maze; novel object recognition
Idiopathic normal pressure hydrocephalus (INPH) is a syndrome of ventriculomegaly, gait impairment, cognitive decline and incontinence that occurs in an elderly population prone to many types of comorbidities. Identification of the comorbidities is thus an important part of the clinical management of INPH patients. In 2011, a task force was appointed by the International Society for Hydrocephalus and Cerebrospinal Fluid Disorders (ISHCSF) with the objective to compile an evidence-based expert analysis of what we know and what we need to know regarding comorbidities in INPH. This article is the final report of the task force. The expert panel conducted a comprehensive review of the literature. After weighing the evidence, the various proposals were discussed and the final document was approved by all the task force members and represents a consensus of expert opinions. Recommendations regarding the following topics are given: I. Musculoskeletal conditions; II. Urinary problems; III. Vascular disease including risk factors, Binswanger disease, and white matter hyperintensities; IV. Mild cognitive impairment and Alzheimer disease including biopsies; V. Other dementias (frontotemporal dementia, Lewy body, Parkinson); VI. Psychiatric and behavioral disorders; VII. Brain imaging; VIII. How to investigate and quantify. The task force concluded that comorbidity can be an important predictor of prognosis and post-operative outcome in INPH. Reported differences in outcomes among various INPH cohorts may be partly explained by variation in the rate and types of comorbidities at different hydrocephalus centers. Identification of comorbidities should thus be a central part of the clinical management of INPH where a detailed history, physical examination, and targeted investigations are the basis for diagnosis and grading. Future INPH research should focus on the contribution of comorbidity to overall morbidity, mortality and long-term outcomes.
Hydrocephalus; Normal pressure; Comorbidity; Review; Guidelines; Task force
The following article from Small GTPases, “Scientific Yellow Journalism” by Anica Klockars and Michael J. Williams, published online on 20 September 2012 (doi: 10.4161/sgtp.22289; http://www.landesbioscience.com/journals/smallgtpases/article/22289/) by Landes Bioscience and subsequently published in print in Small GTPases 2012 3(4):201 has been retracted by agreement between the authors and the journal’s Editor in Chief, Michael J. Williams (also an author of the paper).
A recent conference entitled Purines in Cell Signalling: Targets for New Drugs, held in Rockville, Maryland, in September, 1989, was one indication of the increasing interest in developing agonists and antagonists of P1-(adenosine) and P2-(ATP) purinoceptors  as potential therapeutic agents. Extracellular adenosine, acting at its membrane bound A1 and A2 receptors, is a ubiquitous modulator of cellular activity. The purine can arise from several sources including ATP hydrolysis by ectokinase activity in the region of the nerve terminal  and from S-adenosylhomocysteine  and ATP within the cell. Together with its more stable analogs, adenosine is a potent inhibitor of neurotransmitter release in both the central and peripheral nervous systems, and in cardiac, adipose and other tissues. Adenosine can also affect blood pressure and heart rate as well as modulate the function of the immune, inflammatory, gastrointestinal, renal and pulmonary systems, either via its effects on transmitter release or directly via receptor mechanisms altering intracellular transduction processes.
Neonatal exposure to 3,4-methylenedioxymethamphetamine (MDMA) produces long-term learning and memory deficits and increased anxiety-like behavior. The mechanism underlying these behavioral changes is unknown but we hypothesized that it involves perturbations to the serotonergic system as this is the principle mode of action of MDMA in the adult brain. During development 5-HT is a neurotrophic factor involved in neurogenesis, synaptogenesis, migration, and target region specification. We have previously showed that MDMA exposure (4×10 mg/kg/day) from P11-20 (analogous to human third trimester exposure) induces ~50% decreases in hippocampal 5-HT throughout treatment. To determine whether MDMA-induced 5-HT changes are determinative, we tested if these changes could be prevented by treatment with a selective serotonin reuptake inhibitor (citalopram: CIT). In a series of experiments we evaluated the effects of different doses and dose regimens of CIT on MDMA-induced 5-HT depletions in three brain regions (hippocampus, entorhinal cortex, and neostriatum) at three time-points (P12, P16, P21) during the treatment interval (P11-20) known to induce behavioral alterations when animals are tested as adults. We found that 5 mg/kg CIT administered twice daily significantly attenuated MDMA-induced 5-HT depletions in all three regions at all three ages but that the protection was not complete at all ages. Striatal dopamine was unaffected. We also found increases in hippocampal NGF and plasma corticosterone following MDMA treatment on P16 and P21, respectively. No changes in BDNF were observed. CIT treatment may be a useful means of interfering with MDMA-induced 5-HT reductions and thus permit tests of the hypothesis that the drug’s cognitive and/or anxiety effects are mediated through early disruptions to 5-HT dependent developmental processes.
serotonin; dopamine; development; ecstasy; corticosterone; citalopram
Neonatal exposure to 3,4-methylenedioxymethamphetamine
long-term learning and memory deficits and increased anxiety-like
behavior. The mechanism underlying these behavioral changes is unknown,
but we hypothesized that it involves perturbations to the serotonergic
system as this is the principal mode of action of MDMA in the adult
brain. During development, 5-HT is a neurotrophic factor involved
in neurogenesis, synaptogenesis, migration, and target region specification.
We have previously shown that MDMA exposure (4 × 10 mg/kg/day)
from postnatal day (P)11–20 (analogous to human third trimester
exposure) induces ∼50% decreases in hippocampal 5-HT throughout
treatment. To determine whether MDMA-induced 5-HT changes are determinative,
we tested if these changes could be prevented by treatment with a
selective serotonin reuptake inhibitor (citalopram: CIT). In a series
of experiments, we evaluated the effects of different doses and dose
regimens of CIT on MDMA-induced 5-HT depletions in three brain regions
(hippocampus, entorhinal cortex, and neostriatum) at three time points
(P12, P16, P21) during the treatment interval (P11–20) known
to induce behavioral alterations when animals are tested as adults.
We found that 5 mg/kg CIT administered twice daily significantly attenuated
MDMA-induced 5-HT depletions in all three regions at all three ages
but that the protection was not complete at all ages. Striatal dopamine
was unaffected. We also found increases in hippocampal NGF and plasma
corticosterone following MDMA treatment on P16 and P21, respectively.
No changes in BDNF were observed. CIT treatment may be a useful means
of interfering with MDMA-induced 5-HT reductions and thus permit tests
of the hypothesis that the drug’s cognitive and/or anxiety
effects are mediated through early disruptions to 5-HT dependent developmental
Serotonin; dopamine; development; ecstasy; corticosterone; citalopram
The potassium channel Kv1.2 alpha-subunit is expressed in cerebellar Purkinje cell (PC) dendrites where its pharmacological inhibition increases excitability (Khavandgar et al., 2005). Kv1.2 is also expressed in cerebellar basket cell (BC) axon terminals (Sheng et al., 1994), where its blockade increases BC inhibition of PCs (Southan and Robertson, 1998a). Secretin receptors are also expressed both in PC dendrites and BC axon terminals (reviewed in (Yuan et al.). The effect of secretin on PC excitability is not yet known, but, like Kv1.2 inhibitors, secretin potently increases inhibitory input to PCs (Yung et al., 2001). This suggests secretin may act in part by suppressing Kv1.2. Receptor-mediated endocytosis is a mechanism of Kv1.2 suppression (Nesti et al., 2004). This process can be regulated by protein kinase A (PKA) (Connors et al., 2008). Since secretin receptors activate PKA (Wessels-Reiker et al., 1993), we tested the hypothesis that secretin regulates Kv1.2 trafficking in the cerebellum. Using cell surface protein biotinylation of rat cerebellar slices, we found secretin decreased cell-surface Kv1.2 levels by modulating Kv1.2 endocytic trafficking. This effect was mimicked by activating adenylate cyclase (AC) with forskolin, and was blocked by pharmacological inhibitors of AC or PKA. Imaging studies identified the BC axon terminal and Purkinje cell dendrites as loci of AC-dependent Kv1.2 trafficking. The physiological significance of secretin regulated Kv1.2 endocytosis is supported by our finding that infusion into the cerebellar cortex of either the Kv1.2 inhibitor Tityustoxin-Kα, or of the Kv1.2 regulator secretin, significantly enhances acquisition of eyeblink conditioning in rats.
In rats neonatal (+)-methamphetamine (MA) exposure and maternal separation stress increase corticosterone during treatment and result in learning and memory impairments later in life. Early-life stress also changes later responses to acute stress. We tested the hypothesis that neonatal MA exposure would alter adult corticosterone after acute stress or MA challenge. Rats were treated with MA (10 mg/kg × 4/day), saline, or handling on postnatal (P) days 11–15 or 11–20 (days that lead to learning and memory impairments at this dose). As adults, corticosterone was measured before and after 15 min forced swim (FS) or 15 min forced confinement (FC), counterbalanced, and after an acute MA challenge (10 mg/kg) given last. FS increased corticosterone more than FC; order and stress type interacted but did not interact with treatment; treatment interacted with FS but not with FC. In the P11–15 regimen, MA-treated rats showed more rapid increases in corticosterone after FS than controls. In the P11–20 regimen, MA-treated rats showed a trend toward more rapid decrease in corticosterone after FS. No differences were found after MA challenge. The data do not support the hypothesis that neonatal MA causes changes in adult stress responsiveness to FS, FC, or an acute MA challenge.
Methamphetamine; neonatal methamphetamine; stress; forced swim; corticosterone; forced confinement
Antibody class defines function in B cell immunity, but how class is propagated into B cell memory remains poorly understood. Here, we demonstrate that memory B cell subsets unexpectedly diverge across antibody class through the differential impact of major transcriptional regulators. Conditional genetic deletion of Tbx21 selectively blocks the formation and antigen-specific response of IgG2a memory B cells in vivo. Cell intrinsic T-bet expression regulates STAT1 expression, steady-state cell survival and IgG2a BCR transcription. In contrast, RORα was differentially expressed in IgA memory B cells with siRNA knockdown and chemical inhibition supporting its selective control in cell survival and IgA BCR transcription. Thus, divergent transcriptional regulators dynamically maintain subset integrity to promote specialized immune function within class-specific memory B cells.
Purpurinimide methyl esters, bearing variable lengths of N-substitutions, were conjugated individually to a cyanine dye with a carboxylic acid functionality. The results obtained from in vitro and in vivo studies showed a significant impact of the linkers joining the phototherapeutic and fluorescence imaging moieties. The photosensitizer-fluorophore conjugate with a PEG linker showed the highest uptake in the liver, whereas the conjugate linked with two carbon units showed excellent tumor-imaging and PDT efficacy at 24 h postinjection. Whole body imaging and biodistribution studies at variable time points portrayed enhanced fluorescent uptake of the conjugates in the tumor compared to the skin. Interestingly the conjugate with the shortest linker and the one joining with two carbon units showed faster clearance from normal organs e. g., liver, kidney, spleen, lung compared to tumors. Both imaging and PDT efficacy of the conjugates were performed in BALB/c mice bearing Colon26 tumors. Compared to the others, the short linker conjugate showed poor tumor fluorescent properties and as a corollary does not exhibit the dual functionality of the photosensitizer-fluorophore conjugate. For this reason, it was not evaluated for in vivo PDT efficacy. However, in Colon26 tumor cells (in vitro), the short linker was highly effective. Among the conjugates with variable linkers, the rate of energy transfer from the purpurinimide moiety to the cyanine moiety increased with deceasing linker length, as examined by femtosecond laser flash photolysis measurements. No electron transfer from the purpurinimide moiety to the singlet excited state of the cyanine moiety or from the singlet excited state of the cyanine moiety to the purpurinimide moiety occurred as indicated by a comparison of transient absorption spectra with spectra of the one-electron oxidized and one-electron reduced species of the conjugate obtained by spectroelectrochemical measurements.
Background and Purpose
Patients with intracerebral hemorrhage (ICH) and intraventricular hemorrhage (IVH) have a reported mortality of 50–80%. We evaluated a clot lytic treatment strategy for these patients in terms of mortality, ventricular infection, and bleeding safety events and for its effect on the rate of intraventricular clot lysis.
48 Patients were enrolled at 14 centers and randomized to treatment with 3mg recombinant tissue plasminogen activator (rt-PA) or placebo. Demographic characteristics, severity factors, safety outcomes (mortality, infection, bleeding), and clot resolution rates were compared in the two groups.
Severity factors, including admission GCS, ICH volume, IVH volume and blood pressure, were evenly distributed, as were adverse events except for an increased frequency of respiratory system events in the placebo-treated group. Neither ICP nor Cerebral Perfusion pressure (CPP) differed substantially between treatment groups on presentation, with EVD closure, or during the active treatment phase. Frequency of death and ventriculitis was substantially lower than expected and bleeding events remained below the pre-specified threshold: mortality (18%, rt-PA; 23%, placebo); ventriculitis (8%, rt-PA; 9%, placebo); symptomatic bleeding (23%, rt-PA; 5% placebo, which approached statistical significance (p=0.1)). The median duration of dosing was 7.5 days for rt-PA and 12 days for placebo. There was a significant beneficial effect of rt-PA on rate of clot resolution
Low-dose rt-PA for the treatment of ICH with IVH has an acceptable safety profile compared to placebo and prior historical controls. Data from a well-designed Phase III clinical trial, such as CLEAR III, will be needed to fully evaluate this treatment.
Clinical Trial Registration Information
Participant enrollment began prior to July 1, 2005.
intracerebral hemorrhage; intraventricular hemorrhage; tissue plasminogen activator; thrombolysis
Methylphenidate (MPD) is the most prescribed drug for attention deficit hyperactivity disorder. Licit and illicit use also occurs during pregnancy, however the effects from this use on offspring development is unknown. To model late gestational exposure, Sprague-Dawley litters were treated with 0, 5, 10, 20, or 30 mg/kg × 4/day every 2 h with MPD on postnatal days 11–20 (within-litter design; days chosen to be comparable to human third trimester brain development). During treatment, body weights were decreased in MPD-treated groups; weight recovery occurred in all but the MPD-30 group by start of testing. MPD-treated rats showed no changes in anxiety (elevated zero maze), swimming ability (straight channel swimming), or spatial learning/reference memory (Morris water maze). MPD does not appear to pose a risk to these CNS functions after exposure during a stage of rat development analogous to third trimester human brain development.
Methylphenidate; Morris water maze; spatial learning; reference memory; developmental exposure; elevated zero maze; anxiety; rats
MicroRNAs (miRNAs) are a class of short, single-stranded non-protein coding gene products which can regulate the gene expression through post-transcriptional inhibition of messenger RNA (mRNA) translation. They are known to be involved in many essential biological processes including development, insulin secretion, and adipocyte differentiation. miRNAs are involved in complex metabolic processes, such as energy and lipid metabolism, which have been studied in the context of diabetes and obesity. Obesity, hyperlipidemia (elevated levels of blood lipids), and insulin resistance are strongly associated with the onset of type 2 diabetes. These conditions are also associated with aberrant expression of multiple essential miRNAs in pancreatic islets of Langerhans and peripheral tissues, including adipose tissue. A thorough understanding of the physiological role these miRNAs play in these tissues, and changes to their expression under pathological conditions, will allow researchers to develop new therapeutics with the potential to correct the aberrant expression of miRNAs in type 2 diabetes and obesity.
The new Certas™ shunt for the treatment of hydrocephalus has seven standard pressure settings that according to the manufacturer range from 36 to 238 mmH2O, and an additional “Virtual Off” setting with an opening pressure >400 mmH2O. Information on actual pressure response and reliability of shunt performance is important in clinical application, especially the “Virtual Off” setting as a non-surgical replacement for shunt ligation. The objective of this study was to evaluate the in-vitro hydrodynamic performance of the Certas™ shunt.
Six new Certas™ shunts with proximal and distal catheters were tested with an automated, computerized test system that raised the pressure from zero to a maximum pressure and back to zero at each valve setting. Opening pressure and flow resistance were determined.
For settings 1–7 the measured opening pressure range was 26 to 247 mmH2O, and the mean change in opening pressure for a one-step adjustment was between 33 and 38 mmH2O. For setting 8 (“Virtual Off”) the measured mean opening pressure was 494 ± 34 mmH2O (range 451 to 556 mmH2O). The mean outflow resistance was 7.0 mmHg/ml/min (outflow conductance 17.9 μl/s/kPa).
The six shunts had similar characteristics and closely matched the manufacturer’s specifications for opening pressure at settings 1–7. The opening pressure for the “Virtual Off” setting was nearly 500 mmH2O, which is 100 mmH2O higher than the manufacturer’s specification of “>400” and should be functionally off for most patients with communicating hydrocephalus. Clinical studies are needed to evaluate if the CSF dynamic profile persists after implantation in patients.
Hydrocephalus; Normal pressure hydrocephalus; CSF; Cerebrospinal fluid; Shunt; Intracranial pressure; Outflow resistance; Conductance
Methamphetamine (MA) is an abused stimulant which can result in cognitive deficits and monoamine depletions. Animal models of neurotoxic MA exposure show reductions in dopamine, serotonin, and their associated transporters. MA abuse can result in long-term attention, working memory, and executive function deficits in humans and deficits in route-based egocentric learning, novel object recognition, and novel odor preference in rodents. MA has also been shown to affect brain-derived neurotrophic factor (BDNF) in humans and rodents. This experiment examined the effects of a MA binge dosing regimen (10 mg/kg × 4 at 2 h intervals, s.c.) in Sprague-Dawley rats on BDNF, tropomyosin receptor kinase B (TrkB), and tyrosine hydroxylase (TH) mRNA expression, and plasma corticosterone. Tissues were collected 1, 7, and 24 h following the last MA dose. Expression of BDNF and TrkB mRNA was analyzed using in situ hybridization with cRNA probes. Frontal, parietal, and entorhinal cortical BDNF mRNA expression were increased by MA exposure at all time-points. Increases in BDNF mRNA message were also seen in the hippocampal CA1, prefrontal cortex (PFC), piriform cortex, and locus coeruleus but only at specific times. TrkB mRNA expression was modified in several subregions of the hippocampus as well as in PFC and striatum. TH mRNA was increased at the 1 h time-point in the substantia nigra pars compacta with no differences noted at the other times. Corticosterone levels were increased at all three time-points. The findings suggest that BDNF and its receptor may be upregulated as a compensatory mechanism after MA exposure.
Methamphetamine; brain-derived neurotrophic factor; BDNF; tropomyosin receptor kinase B; TrkB
(+)-Methamphetamine (MA), (±)-3,4-methylenedioxymethamphetamine (MDMA), (+)-amphetamine (AMPH), and (±)-fenfluramine (FEN) are phenylethylamines with CNS effects. At higher doses, each induces protracted reductions in brain dopamine and/or serotonin. Chronic MA and MDMA users show persistent monoamine reductions and cognitive impairments. In rats, similar neurochemical effects can be induced, yet cognitive impairments have been difficult to demonstrate. We recently showed that rats treated on a single day with MA (10 mg/kg × 4 at 2 h intervals) exhibit impaired egocentric learning (Cincinnati water maze; CWM) without affecting spatial learning (Morris water maze) (Herring et al., 2008). Whether this effect is unique to MA or is a general characteristic of these drugs is unknown. Accordingly, this experiment compared these drugs on CWM performance. Drugs were given s.c. in four doses at 2 h intervals. MA doses were 10 or 12.5 mg/kg/dose, AMPH 25 mg/kg/dose (to match MA12.5-induced hyperthermia), MDMA 15 mg/kg/dose (previously established hyperthermia-inducing dose), and FEN 16.5 mg/kg/dose (equimolar to MA12.5). Two weeks later, rats were tested in the CWM (2 trials/day, 21 days). AMPH and MA (both doses) induced significant increases in CWM errors and latency to reach the goal with no differences in swim speed. MDMA and FEN did not significantly alter learning. Given that FEN selectively and MDMA preferentially affect serotonin whereas AMPH selectively and MA preferentially affect dopamine, the data suggest that egocentric learning may be predominantly dopaminergically-mediated.
Methamphetamine; 3,4-methylenedioxymethamphetamine; MDMA; d-amphetamine; fenfluramine; maze learning; swimming maze; Cincinnati water maze; egocentric learning; hyperthermia; route-based learning; rat
In the title compound, [AuI(C19H15OP)2], the complete molecule is generated by the application of twofold symmetry. The AuI atom is in a trigonal–planar geometry within an IP2 donor set with the greatest distortion seen in the P—Au—P angle [128.49 (3) °]. Close intramolecular Au⋯O interactions [3.172 (3) Å] are observed. No specific intermolecular interactions are noted in the crystal packing.
Sodium and potassium-activated adenosine triphosphatases (Na,K-ATPase) are ubiquitous, participate in osmotic balance and membrane potential, and are composed of α, β, and γ subunits. The α subunit is required for the catalytic and transport properties of the enzyme and contains binding sites for cations, ATP, and digitalis-like compounds including ouabain. There are four known α isoforms; three that are expressed in the CNS in a regional and cell-specific manner. The α2 isoform is most commonly found in astrocytes, pyramidal cells of the hippocampus in adults, and developmentally in several other neuronal types. Ouabain-like compounds are thought to be produced endogenously in mammals, bind the Na,K-ATPase, and function as a stress-related hormone, however, the impact of the Na,K-ATPase ouabain binding site on neurobehavioral function is largely unknown. To determine if the ouabain binding site of the α2 isoform plays a physiological role in CNS function, we examined knock-in mice in which the normally ouabain-sensitive α2 isoform was made resistant (α2R/R) while still retaining basal Na,K-ATPase enzymatic function. Egocentric learning (Cincinnati water maze) was impaired in adult α2R/R mice compared to wild type (WT) mice. They also exhibited decreased locomotor activity in a novel environment and increased responsiveness to a challenge with an indirect sympathomimetic agonist (methamphetamine) relative to WT mice. The α2R/R mice also demonstrated a blunted acoustic startle reflex and a failure to habituate to repeated acoustic stimuli. The α2R/R mice showed no evidence of altered anxiety (elevated zero maze) nor were they impaired in spatial learning or memory in the Morris water maze and neither group could learn in a large Morris maze. These results suggest that the ouabain binding site is involved in specific types of learning and the modulation of dopamine-mediated locomotor behavior.
Na-K ATPase; ouabain; acoustic startle response; egocentric learning; dopamine; methamphetamine-induced locomotor activity
Despite restrictions, exposure to lead (Pb) continues. Moreover, exposure varies and is often higher in lower socioeconomic status (SES) families and remains a significant risk to cognitive development. Stress is another risk factor. Lower SES may be a proxy for stress in humans. When stress and Pb co-occur, risk may be increased. A few previous experiments have combined Pb with intermittent or acute stress but not with chronic stress. To determine if chronic developmental stress affects outcome in combination with Pb, we tested such effects on growth, organ weight, brain monoamines, and response to an acute stressor. Sprague Dawley rats were gavaged with Pb acetate (1 or 10 mg/kg) or vehicle every other day from postnatal day (P)4-29 and reared in standard or barren cages. Subsets were analyzed at different ages (P11, 19, 29). Chronic stress did not alter blood Pb levels but altered HPA axis response during early development whereas Pb did not. Pb treatment and rearing each altered organ to body weight ratios, most notably of thymus weights. Both Pb and rearing resulted in age- and region-dependent changes in serotonin and norepinephrine levels and in dopamine and serotonin turnover. The model introduced here may be useful for investigating the interaction of Pb and chronic developmental stress.
Maternal stress; Lead (Pb); corticosterone; serotonin; dopamine; barren cage rearing