Abstract
We have already reported that the degree of the retrieval in the condition taste aversion memory (CTAM) represents age-related differences during sexual maturation of mice, suggesting the hormonal effect secreted temporally during maturation period on the extinction mechanism of CTAM. We chose an androgenic hormone, testosterone, in order to examine the effect of sexual maturation on acquisition and retention of CTAM. Gonadectomized male mice (C57BL/6J) were implanted with pellets containing several doses of testosterone (0-2 mg) at 5 weeks after birth. At 7 weeks, mice, which acquired CTAM by application of 0.5% sodium saccharin as a conditioned stimulus (CS) and an i.p.injection of 0.15 M LiCl as an unconditioned stimulus (US), were followed by the extinction period for 1 week. At 12 weeks, mice implanted the silicon tube containing 0.5 and 1.0 mg testosterone showed significantly higher retrieval than mice implanted not only the silicon tube containing 0 but also 2.0 mg testosterone. Thus, these results suggest that testosterone participates in the maturation process of the extinction mechanism of CTAM in the mice brain. [J Physiol Sci. 2008;58 Suppl:S92]
