| First Author | Flood JF | Year | 1995 |
| Journal | Physiol Behav | Volume | 57 |
| Issue | 4 | Pages | 669-73 |
| PubMed ID | 7777601 | Mgi Jnum | J:27802 |
| Mgi Id | MGI:75285 | Doi | 10.1016/0031-9384(94)00318-1 |
| Citation | Flood JF, et al. (1995) Age-related decrease of plasma testosterone in SAMP8 mice: replacement improves age-related impairment of learning and memory. Physiol Behav 57(4):669-73 |
| abstractText | Corticosterone increases with aging but pregnenolone, dehydroepiandrosterone, and testosterone decrease. The marked decrease in hormones that occurs with aging may contribute to the age-related deficit in learning and memory. Administration of these hormones after training was found to improve long-term memory processing in normal young mice. SAMP8 (P8) mice show an age-related loss of learning and memory for a variety of tasks whereas age-matched control mice of the closely related SAMR1 (R1) strain do not. In this study, we found an age-related decrease in serum testosterone levels of 71% between P8 mice 4 and 12 months of age, but only a 26% decrease between R1 mice of the same ages. The difference between the P8 mice was significant (p < 0.01) and the difference between the R1 mice was not. The decrease in testosterone in 12-month-old P8 mice was not accompanied by gross morphological change in the testes. A SC testosterone implant, sufficient to increase plasma testosterone levels to 414 +/- 25 ng/dl, alleviated impaired learning and memory of a foot shock avoidance task in P8 mice. Castration of 4-month-old P8 mice did not produce a deterioration in learning and memory, indicating that low levels of testosterone per se are not responsible for the impairment seen in 12-month-old P8 mice. This suggests that impaired cognitive functioning of the older P8 mice was due to an interaction of aging and reduced testosterone levels. |
