Intracranial sites regulating the biphasic action of @entity1420 in @entity172 -primed XXXX .

@entity172 @entity1420 @entity1640 @entity146 @entity1515 @entity2339 @entity329
@entity1640 and mesencephalic neural sites regulating the biphasic effect of @entity1420 (P) were investigated using the hormone implantation technique in ovariectomized female @entity329 primed with @entity172 . Double barreled cannulae were implanted unilaterally and bilaterally in the medial preoptic area, anterior @entity2339 , @entity2339 ( @entity2339 ), central gray, or interpeduncular nucleus. Testing was conducted using a sequential paradigm; facilitation tests commenced after 44 h of @entity172 priming. P-filled cannulae placed in the @entity2339 region facilitated @entity146 in 42% and 60% of unilaterally and bilaterally implanted females, respectively. In the anterior @entity2339 , only P implants adjacent to the @entity2339 area effectively promoted receptivity. @entity146 was also observed in 20-36% of females with P implants in the medial preoptic area. P implants in central gray and interpeduncular nucleus regions had no significant facilitating effect on sexual behavior. Tests for inhibition occurred 24 h after facilitation testing and consisted of a pretest, followed by systemic P administration and a behavioral test 4-5 h later. During the pretest for inhibition, females that were receptive in the facilitation test attacked males more rapidly than previously nonreceptive animals and showed decrements in @entity1515 scores after systemic P delivery. This biphasic effect of P completely inhibited receptivity among several animals in the @entity2339 group. Additional experiments, however, investigating the biphasic effect of P implants in the @entity2339 suggested that the occurrence of copulation in the facilitation test may have been involved in mediating the subsequent increase in aggressive behavior and the suppression of sexual responsiveness in the inhibition test. Nevertheless, a final experiment showed that when P was implanted sequentially in the @entity2339 , facilitation and, more importantly, a later reduction in @entity1515 behavioral scores occurred even when copulation was eliminated in the facilitation test. P implants in mesencephalic regions exerted no significant inhibitory effect on receptivity. These findings demonstrate that the biphasic action of P in the female hamster is regulated by nerve cells located in the diencephalon, especially in the @entity2339 region.
