F344 rats possess both an obligate inhibition of testicular development in SD and a further facultative inhibition of testicular development in SD by FR or by neonatal TP (Figs. 2 and 4). Together, the obligate and facultative responses inhibit reproductive maturation in SD almost as strongly as observed in some highly photoresponsive rodents, but for less than half as many weeks. The level of food restriction we chose was relatively modest, and it is possible that greater food restriction, which would be likely for some animals in the wild, might produce greater reproductive inhibition. In combination with SD, neonatal TP treatment inhibits testicular growth to an extent as great as that observed in some highly photoresponsive rodents (Fig. 2). Clearly, reproductive development is not maximally inhibited by SD alone in F344 rats. buy antibiotics online
The effect of neonatal TP and SD on F344 rats was greater than the effect of neonatal TP and either blinding or SD on Sprague-Dawley, Wistar, or Wistar-Kon-arovice strains of rats. Similarly, the effect of FR with SD on F344 rats appears to be greater than in other strains (e.g., ). Thus, SD alone or in combination with FR or neonatal TP induces greater reproductive inhibition in F344 rats than in other strains.