Level of neuroactive steroids in the brain and sex-related peculiarities of formation and extinction of conditioned reflex in rats

• Published in: Journal of evolutionary biochemistry and physiology Vol. 46; no. 4; pp. 366 - 373
• Main Authors: Sashkov, V. A, Selverova, N. B, Morenkov, E. D, Ermakova, I. V
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : SP MAIK Nauka/Interperiodica 01.08.2010; SP MAIK Nauka/Interperiodica; Springer Nature B.V
• Subjects: Animal cognition; Animal memory; Animal Physiology; Biochemistry; Biomedical and Life Sciences; Comparative and Ontogenic Physiology; Evolutionary Biology; Life Sciences; Neurosciences; Rodents; Steroids; neuroactive steroids; learning; memory; testosterone; neurosteroids; estradiol
• ISSN: 0022-0930; 1608-3202
• DOI: 10.1134/s0022093010040058

Sex-related peculiarities of dynamics of brain sex steroids in the process of learning and extinction of the conditioned reflex of passive avoidance have been studied in model experiment. Prior to learning of the conditioned reflex, female rats were found to be distinguished by manifestation of anxiety and fear as compared with male rats. At formation of the conditioned reflex, no significant sex-related differences were detected between males and females, whereas extinction of the conditioned reaction of passive avoidance in males occurred by 2-3 days faster than in females. At learning of conditioned reaction of passive avoidance, in sexually mature male rats there was revealed an increase of the testosterone content in various brain structures, especially in hippocampus and frontal cortex, while its level in blood plasma remained unchanged. Also shown was an elevation of estradiol concentration in female amygdale, whereas at extinction of the conditioned reaction of passive avoidance, a rise of estradiol values was noted in hippocampus and cingular cortex. At the same time, the testosterone level in blood plasma did not change, whereas after extinction of the conditioned reflex the estradiol concentration decreased statistically significantly. Different dynamics of changes of the sex steroid levels in brain and blood plasma can indicate a possibility of their formation in the nervous tissue. The performed correlation analysis confirms the concept of selective involvement of testosterone and estradiol of individual brain structures in realization of processes of learning and memory in sexually mature male and female rats.