Can ovariectomy and learning affect prefrontal cortex GABAAα1 receptor distribution in passive avoidance model in rats
Introduction: The interaction between steroid hormones and neurotransmitters such as GABA has been proved. The regulation of muscimol binding to high-affinity GABAA receptors by estradiol and progesterone has been studied within distinct brain regions using in vitro quantitative autoradiography. There are few studies about the mechanism of the effect of steroid hormones on behaviors such as learning and memory and also distribution of GABAAα1 receptor in prefrontal cortex. Therefore, the aim of this study was to evaluate the effect of ovariectomy and passive avoidance learning on distribution of GABAAα1 receptor in prefrontal cortex of rat. Methods: Twenty Sprague-Dawley adult rats were randomly divided into four equal groups: intact without learning; intact with learning; ovariectomy without learning and ovariectomy with learning. The shuttle box was used for induction of passive avoidance learning. Immunohistochemical procedure was used for determination of GABAAα1 receptor distribution. Image Analyzer software was used for determination of color intensity. Results: The data showed that ovariectomy lead to a significant (p<0.05) reduction in GABAAα1 receptor distribution in cg1 (cingulate cortex area1), M1 (primary motor cortex) and M2 (secondary motor cortex). While learning in the presence of ovarian hormones induced a significant decrease (p<0.05) in GABAAα1 receptor distribution in Cg1, M1 and M2 of prefrontal cortex of rats, it significantly increased (p<0.05) receptor distribution in the same regions in the absence of ovarian hormones. Conclusion: According to these results ovariectomy and passive avoidance learning change the distribution of GABAAα1 receptor in Cg1, M1 and M2 regions of prefrontal cortex of rat.