Startle is inhibited when the startling stimulus is preceded 30–300 ms by a weak prepulse. Prepulse inhibition (PPI), an operational measure of sensorimotor gating, is deficient in schizophrenia patients, and reduced in rats and humans by dopamine agonists. The neural basis for the PPI-disruptive effects of dopamine agonists in rats is studied to understand neural circuitry regulating PPI and its deficits in schizophrenia. Existing data suggest that ventral pallidal (VP) GABAergic transmission regulates PPI and its disruption by dopamine agonists. We measured changes in VP GABA efflux and PPI in rats in response to the D2/D3 agonist, quinelorane. Wistar rats were administered quinelorane (vehicle, 0.003 or 0.01 mg/kg). In some rats, VP dialysate was analyzed for GABA content. In others, PPI was assessed using 120 dB(A) startle pulses and prepulses 10 dB over a 70 dB(A) background. Quinelorane reduced GABA efflux, with significant effects for 0.01 but not 0.003 mg/kg, persisting for at least 100 min. Quinelorane reduced PPI for 50 min, an effect significant for both the 0.003 (p<0.05) and 0.01 mg/kg doses (p<0.015). Differences in time course and dose sensitivity of quinelorane effects on VP GABA efflux and PPI are discussed.

Objective: To investigate the effects of 18α-glycyrrhetinic acid (18α-GA) on the expression of type I and III collagen in human and rat hepatic stellate cells (HSC) and to explore the role of TGF-β1/Smad signaling pathway involved.

Methods: Following 18α-GA treatment, the cell viability and cell growth were detected to determine the optimal concentration of 18α-GA. The expressions of TGF-β1/Smad signaling-related genes including type I and III collagen in human and rat HSCs before and after 18α-GA treatment were measured by real time PCR. The expression of related proteins was verified by western blot assay. The phosphorylation level of Smad2 and Smad3 was detected by immunocytochemistry. The DNA binding activities of SP-1, AP-1 and NF-κB were measured by both EMSA and ArrayStar transcription factor activity assay.

Results: 18α-GA could decrease the mRNA and protein expression of Smad3, type I and III collagen, increase the Smad7 expression in human and rat HSCs (P<0.05), and reduce phosphorylation level of Smad3 at 24 h and 48 h after treatment. The DNA binding activities of transcription factors were suppressed by 18α-GA in human and rat HSCs at 24 h, and the activities reduced in a time dependent manner with the lowest activities at 48 h, especially for SP-1.

Conclusion: 18α-GA could inhibit the mRNA and protein expression of type I and III collagen in human and rat HSCs, which may be attributed to down-regulation of Smad3, up-regulation of Smad7, and inhibition of DNA binding activities of SP-1, AP-1 and NF-κB.

Cancer cells have an efficient antioxidant system to counteract their increased generation of ROS. However, whether this ability to survive high levels of ROS has an important role in the growth and metastasis of tumors is not well understood. Here, we demonstrate that the redox protein thioredoxin-like 2 (TXNL2) regulates the growth and metastasis of human breast cancer cells through a redox signaling mechanism. TXNL2 was found to be overexpressed in human cancers, including breast cancers. Knockdown of TXNL2 in human breast cancer cell lines increased ROS levels and reduced NF-κB activity, resulting in inhibition of in vitro proliferation, survival, and invasion. In addition, TXNL2 knockdown inhibited tumorigenesis and metastasis of these cells upon transplantation into immunodeficient mice. Furthermore, analysis of primary breast cancer samples demonstrated that enhanced TXNL2 expression correlated with metastasis to the lung and brain and with decreased overall patient survival. Our studies provided insight into redox-based mechanisms underlying tumor growth and metastasis and suggest that TXNL2 could be a target for treatment of breast cancer.

Introduction

Under specific conditions, a weak lead stimulus, or “prepulse”, can inhibit the startling effects of a subsequent intense abrupt stimulus. This startle-inhibiting effect of the prepulse, termed “prepulse inhibition” (PPI), is widely used in translational models to understand the biology of brain based inhibitory mechanisms and their deficiency in neuropsychiatric disorders. In 1981, four published reports with “prepulse inhibition” as an index term were listed on Medline; over the past 5 years, new published Medline reports with “prepulse inhibition” as an index term have appeared at a rate exceeding once every 2.7 days (n = 678). Most of these reports focus on the use of PPI in translational models of impaired sensorimotor gating in schizophrenia. This rapid expansion and broad application of PPI as a tool for understanding schizophrenia has, at times, outpaced critical thinking and falsifiable hypotheses about the relative strengths vs. limitations of this measure.

Objectives

This review enumerates the realistic expectations for PPI in translational models for schizophrenia research, and provides cautionary notes for the future applications of this important research tool.

Conclusion

In humans, PPI is not “diagnostic”; levels of PPI do not predict clinical course, specific symptoms, or individual medication responses. In preclinical studies, PPI is valuable for evaluating models or model organisms relevant to schizophrenia, “mapping” neural substrates of deficient PPI in schizophrenia, and advancing the discovery and development of novel therapeutics. Across species, PPI is a reliable, robust quantitative phenotype that is useful for probing the neurobiology and genetics of gating deficits in schizophrenia.

Rationale

Prepulse inhibition (PPI) of startle is a measure of sensorimotor gating that is heritable and deficient in certain psychiatric disorders, including schizophrenia. Sprague–Dawley (SD) rats are more sensitive to PPI disruptive effects of dopamine (DA) agonists at long interstimulus intervals (60–120 ms) and less sensitive to their PPI-enhancing effects at short (10–30 ms), compared with Long–Evans (LE) rats. These heritable strain differences in sensitivity to the PPI disruptive effects of DA agonists must ultimately reflect neural changes "downstream" from forebrain DA receptors.

Objective

The current study evaluated the effects of the DA agonist, apomorphine (APO), on ventral pallidal (VP) gamma-aminobutyric acid (GABA) and glutamate efflux and PPI in SD and LE rats.

Methods

PPI was tested in SD and LE rats after vehicle or APO (0.5 mg/kg, subcutaneously (s.c.)) in a within-subject design. In different SD and LE rats, VP dialysate was collected every 10 min for 120 min after vehicle or APO (0.5 mg/kg, s.c.) and analyzed for GABA and glutamate content by capillary electrophoresis (CE) coupled with laser-induced fluorescence (LIF).

Results

As predicted, SD rats exhibited greater APO-induced PPI deficits at long intervals and less APO-induced PPI enhancement at short intervals compared to LE rats. APO significantly reduced VP GABA efflux in SD but not in LE rats; glutamate efflux was unaffected in both strains.

Conclusion

Heritable strain differences in PPI APO sensitivity in SD vs LE rats parallel, and may be mediated by, strain differences in the VP GABA efflux.

AIM: To isolate and identify differentially expressed proteins between cancer and normal tissues of gastric cancer by two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

METHODS: Soluble fraction proteins of gastric cancer tissues and paired normal tissues were separated by 2-DE. The differentially expressed proteins were selected and identified by MALDI-TOF-MS and database search.

RESULTS: 2-DE profiles with high resolution and reproducibility were obtained. Twenty-three protein spots were excised from sliver staining gel and digested in gel by trypsin, in which fifteen protein spots were identified successfully. Among the identified proteins, there were ten over-expressed and five under-expressed proteins in stomach cancer tissues compared with normal tissues.

CONCLUSION: In this study, the well-resolved, reproducible 2-DE patterns of human gastric cancer tissue and paired normal tissue were established and optimized and certain differentially-expressed proteins were identified. The combined use of 2-DE and MS provides an effective approach to screen for potential tumor markers.