Genetic approaches to CNS disorders with particular reference to GABAA-receptor mutations

Anticonvulsant and sedative-hypnotic activity screening of pearl and nacre (mother of pearl)

ETHNOPHARMACOLOGICAL RELEVANCE

Pearl and nacre are valuable traditional medicines to treat palpitations, convulsions or epilepsy in China for thousands of years. However, the active ingredients are not clear till now.

AIM OF THE STUDY

The main purpose of the current investigation was to assess the anticonvulsant and sedative-hypnotic activity of pearl powder and nacre powder, including their corresponding 6 protein extracts.

MATERIAL AND METHODS

Determination of the amino acid composition of the obtained protein was carried out by ultra-performance liquid chromatography (UPLC) combined with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) pre-column derivatisation. The influence of the tested drugs on locomotor activity and convulsions latency was recorded. The contents of 5-Hydroxytryptamine (5-HT) and γ-aminobutyric acid (GABA) in brain were detected by enzyme-linked immunesorbent assay (ELISA) kits. In addition, immunohistochemistry was carried out to evaluate the changes of 5-HT3 and GABAB. In parallel, the expressions of them were demonstrated by western blot.

RESULTS

The obtained data suggested that pearl original powder (1.1g/kg), pearl water-soluble protein (0.2g/kg), pearl acid-soluble protein (0.275g/kg), pearl conchiolin protein (1.1g/kg), nacre original powder (1.1g/kg), nacre water-soluble protein (0.2g/kg), nacre acid-soluble protein (0.7g/kg) and nacre conchiolin protein (1.1g/kg) could down-regulate the expression of 5-HT3 and up-regulate the level of GABAB to varying degrees compared with the control group. Besides, drug administration also reduced the locomotor activity and increased convulsions latency with a certain mortality.

CONCLUSIONS

These findings correlated with the traditional use of pearl and nacre as sedation and tranquilization agents, thus making them interesting sources for further drug development and also providing critical important evidence for the selection of quality control markers.

GABA promotes survival but not proliferation of parvalbumin-immunoreactive interneurons in rodent neostriatum: an in vivo study with stereology

Amino-acid neurotransmitters regulate a wide variety of developmental processes in the mammalian CNS including neurogenesis, cell migration, and apoptosis. In order to investigate the role of GABA in early development of forebrain interneurons, we determined the survival of parvalbumin-immunoreactive GABAergic interneurons in the adult rat striatum following prenatal exposure to either GABA(A) receptor agonist or antagonist. Unbiased stereology was used to quantify parvalbumin-immunoreactive neuron number in the neostriatum of adult rats exposed to the drugs in utero, and the results were compared to pair-fed or vehicle controls. Embryos were exposed to the GABA(A) antagonist (bicuculline) or agonist (muscimol) during previously defined proliferative or post-proliferative periods for parvalbumin-immunoreactive interneurons. Unbiased stereology using the optical fractionator was used to estimate the total number of parvalbumin-immunoreactive neurons in neostriatum of experimental and control rats. No significant alteration in parvalbumin-immunoreactive neuron number was observed in rats treated with either bicuculline (1 or 2mg/kg/day) or muscimol (1mg/kg/day) during the proliferative phase. Administration of bicuculline during the post-proliferative phase significantly reduced parvalbumin-immunoreactive neuron number in the neostriatum. A concomitant decrease in neostriatal volume was also observed, suggesting that the effect is not restricted to parvalbumin-immunoreactive interneurons. Positional analysis revealed loss of normal regional distribution gradients for parvalbumin-immunoreactive neurons in neostriatum of rats exposed to bicuculline in the embryonic post-proliferative phase. This data collectively suggests that GABA promotes survival but not proliferation of parvalbumin-immunoreactive progenitors. GABA may also promote migration of subpopulations of interneurons that ultimately populate the ventral telencephalon.

Modulatory effect of cyclosporin A on tert-butyl hydroperoxide-induced oxidative damage in hepatocytes

In the present work, we followed an in vitro protective action of cyclosporin A (CsA) against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in hepatocytes. Various parameters (cell viability, cytosolic calcium level, rhodamine 123 accumulation as indicator of mitochondrial membrane potential and alanine-aminotransferase leakage from cells) were measured as an index of cytotoxicity. Tert-butyl hydroperoxide (1 mM) significantly increased cytosolic Ca2+ and affected mitochondrial membrane potential. Pretreatment with cyclosporin A (0.5 microM) reduced t-BHP-induced cytosolic Ca2+ increase and ALT (alanine-aminotransferase) leakage, but had no protective effect on t-BHP-induced changes of mitochondrial membrane potential. Our data thus suggest that the mechanism of cytoprotection of CsA on the cytosolic Ca2+ changes and ALT leakage induced by t-BHP, does not directly correlate with protection of t-BHP-induced changes of mitochondrial membrane potential.