Lm. Coolen et al., DEMONSTRATION OF EJACULATION-INDUCED NEURAL ACTIVITY IN THE MALE-RAT BRAIN USING 5-HT1A AGONIST 8-OH-DPAT, Physiology & behavior, 62(4), 1997, pp. 881-891
Previous studies from our laboratory indicated the existence of ejacul
ation-related neural activation within the circuitry underlying matin,
o behavior in the male rat. Clusters of Fos-immunoreactive neurons wer
e present only following ejaculations and not after intromissions. How
ever, it was not clear if this pattern of neural activation was specif
ic to ejaculation or a result of summation of sexual activity precedin
g ejaculation. In the present study, the facilitative effect of the 5-
HT1A receptor agonist 8-OH-DPAT on ejaculatory behavior was used to an
alyze the pattern of Fos immunoreactivity following ejaculation preced
ed by minimal sexual activity. Male rats treated with 8-OH-DPAT (0.4 m
g/kg) achieved ejaculation after a shortened latency and low numbers o
f mounts and intromissions. Ejaculation-induced Fos immunoreactivity w
as present in clusters of neurons in the lateral part of the posterodo
rsal medial amygdala, in two subregions of the posteromedial bed nucle
us of the stria terminalis, in the posterodorsal preoptic nucleus, and
in the parvicellular part of the subparafascicular thalamic nucleus.
Males that ejaculated with the first intromission and were treated wit
h a higher dose of 8-OH-DPAT (0.8 mg/kg) exhibited similar clusters of
Fos-positive neurons in all areas except the posterodorsal preoptic n
ucleus. The results demonstrate the existence of a specific ejaculatio
n-related subcircuit within a larger neural circuitry involved in male
sexual behavior. (C) 1997 Elsevier Science Inc.