Modulation of kappa opioid receptor expression in different brain regions of virgin female rats: effects of prolonged treatment with opioid agonist and the role of steroid hormones.

• Grant number: 10/16741-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2011
• End date: January 31, 2012
• Field of knowledge: Biological Sciences - Pharmacology - Neuropsychopharmacology
• Principal Investigator: Elizabeth Teodorov
• Grantee: Lucas Assis Pereira
• Host Institution: Centro de Matemática, Computação e Cognição (CMCC). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil

Abstract

In accordance with the principles of chronobiology, infradian rhythms that last longer than 24 hours are prevalent in mammals capable of breeding. The estrous cycle is well known in rodents, consisting of 4-5 days and characterized by the stages of proestrus, estrus, metestrus and diestrus. The regulation of the secretion of pituitary gonadotropins is the result of a complex interrelation between the effects of gonadal steroid feedback and influence on brain neurotransmitters in the hypothalamus-pituitary. Studies show that this phenomenon is the central role played by brain opioids, which exert an inhibitory influence particularly in the secretion of gonadotropins. It is known that different kinds of brain opioids (such as beta-enkephalins, enkephalins, dynorphins) exert their action by binding to specific membrane receptors, the best known being called mi, delta and kappa (¼, ´ and º respectively). The receivers, mi are the most well studied and appear to be associated with control of gonadotrophin secretion. Some other studies show that the delta opioid receptors would also be related to the regulation of gonadotrophin secretion, but few studies demonstrate the real participation of kappa receptors in this context. The experiments conducted so far reflect the binding potential of opioidergic agonists, like morphine, which could indicate modulation in the number of active opioid receptor type by the presence / absence of steroid hormones and physiological consequences. This study will use current techniques of molecular biology to assess the patterns of gene expression Oprk1 coding for the kappa opioid receptor and the KOR protein products in the hypothalamus, striatum and PAG of virgin rats and adult OVX and treated or not with morphine, E2 and P according to the experimental design.