Young, Lauriann E.; Benjamin, L. C.; Young, Ronald E.
Author Affiliation, Ana.
Department of Basic Medical Sciences
Gender and estrous cycle variations on avoidance learning: Effects of low dose amphetamine and cocaine
Alzheimer's Disease Review
Date of Publication
A fundamental difference between the genders is that females are influenced by fluctuating hormonal levels, whereas in males, hormonal levels are stable. Given the existence of the dopaminergic neuroendocrinological system, fluctuations in hormonal status may be expected to influence dopamine-modulated activity. This study was therefore, designed to evaluate the influence of hormonal status (gender and estrous cycle) on learning in male and female rats and to determine whether this difference is affected by dopaminergic agonists (cocaine and amphetamine). Rats were exposed to electric foot-shocks in a confined arm of a Y-maze. Exploratory and avoidance behaviours were tested 24 hours following training (trial 1) and 2 weeks subsequently (trial 2). Amphetamine ( 1 mg/kg/ml) stimulated exploratory behaviour; whereas, cocaine (1 mg/kg/ml) had a depressant effect at trial 1. Generally, 2 weeks were sufficient to recover from the aversive experience, but amphetamine treatment appeared to have a diminished effect at trial 2. Avoidance learning was significantly less in oestrous females than in diestrous females and male rats. These results indicate that hormonal status influences learning and may have clinical implications for persons on oestrogen therapy. Single low doses of cocaine and amphetamine did not produce significant effects on avoidance learning.....