Surveying steroid participation on GABA- related activities

gamma-aminobutyricacid [GABA], a major neurotransmitter in the central nervous system, also acts as a paracrine or autocrine signaling molecule in endocrine tissues such as the pancreatic islets, adenohypophysis, and testis. It has been demonstrated that metabolites of progesterone and corticosterone naturally act via the GABA[A] - membrane receptor and they have sedative-hypnotic, anxiolytic, anticonvulsant, muscle-relaxant and anesthetic drugs properties. Also the brain as a steroidogenic organ contributes to produce these steroids. The aim of this study was to find out the steroids participation on the GABA- related activities. An injection canula was inserted into lateral ventricle of the sham and experimental adult female rats by stereotaxic surgery. One week late, at proesterus day, diazepam [GABA[A]-receptor agonist] with doses of 250 and 500microg/rat, bicuculine [GABA[A]-receptor antagonist] with doses of 1.5 and 3 ng/rat, baclofen [GABA[B] -receptor agonist] with doses of 4.27 and 8.54 microg/rat and CGP35348 [GABA[B] -receptor antagonist] with doses of 3 and 5 micro g/rat were intracerebroventriculary [ICV] injected to the experimental groups, while equal volume [2 micro l] of artificial CSF was injected to the sham operated group. Blood samples were collected thrice at 9 AM, 11 AM and 1PM. The serum progesterone level was determined using RIA method. Data were analyzed by one way ANOVA and Duncans test at p<0.05 for the significant level. The results showed that GABAergic system activity via both GABA[A] and GABA[B] receptors has significantly changed the serum progesterone level Comparing the results of this research with earlier studies, it is concluded that GABAergic system has a close relation with steroidogenesis and the steroids participate in GABA- related activities

[Role of central GABA[B] receptor in control of estraidol hormones secretion during proestrus phase in female rats]

The effect of ICV injection of baclofen [GABA[B] agonist and CGP35348 [GABA[B] antagonist] on serum concentration of estradiol and progesterone in proestrous phase. Experimental study. Twenty female Sperague Dawley rats weighning 200-250g were used. For ICV injection a director canula was inserted into the lateral ventricle by stereotaxic surgery. Each injection was performed 30 min before blood sampling. Blood samples were collected 9, 11 and 13h after initiation of proestrous. Estradiol and progesterone levels were determined using RIA method. Data were analyzed by One Way ANOVA, repeated meature ANOVA and post-hoc Tucky test. The level of significance was at P<0.05. Present data demonstrated that baclofen at doses of 4.27 and 8.54 ng/rat significantly increased and decreased serum concentration of estradiol, respectively [p<0.05]. baclofen at the same doses significantly increased serum concentration of progesterone in 11 a.m and 1 p.m [P<0.05]. CGP35348 in both doses had no significant effect on serum concentration of estradiol, while in 5 g/rat significantly increased the serum concentration of progesterone [P<0.05]. The results indicate that GABA[B] receptor may has an important role in the control of estradiol and progesterone secretion in the proestrous phase of female rats