Lm. Coolen et al., FOS IMMUNOREACTIVITY IN THE RAT-BRAIN FOLLOWING CONSUMMATORY ELEMENTSOF SEXUAL-BEHAVIOR - A SEX COMPARISON, Brain research, 738(1), 1996, pp. 67-82
In the present study a comparison was made between the distribution of
Fos immunoreactivity in the brain of female and male rats following s
uccessive elements of sexual behavior. The distribution of Fos immunor
eactivity following either mounting, eight intromissions or one or two
ejaculations was compared with that in control animals. In both femal
es and males, Fos immunoreactivity was induced in the medial preoptic
nucleus, posteromedial part of the bed nucleus of the stria terminalis
, posterodorsal part of the medial amygdala, and the parvicellular par
t of the subparafascicular thalamic nucleus. In addition, Fos immunore
activity in females was induced in the ventrolateral part and the most
caudoventral part of the ventromedial nucleus of the hypothalamus and
in the premammillary nucleus. Differences between females and males w
ere detected in the phases of sexual activity that resulted in Fos imm
unoreactivity in these brain areas, allowing more insight in the natur
e of the sensory and hormonal stimuli leading to the induction of Fos
immunoreactivity. The posteromedial bed nucleus of the stria terminali
s appears to be involved in chemosensory investigation, while specific
distinct subregions are only activated following ejaculation. In addi
tion, the parvicellular subparafascicular nucleus and the lateral part
of the posterodorsal medial amygdala appear to be involved in the int
egration of viscero-sensory input. The neural circuitries underlying s
exual behavior in males and females appear to be similar in terms of i
ntegration of sensory information. In males the medial preoptic nucleu
s may be regarded as the brain area where the integration of sensory a
nd hormonal stimulation leads to the onset of male sexual behavior, wh
ile in females the ventrolateral part of the ventromedial hypothalamic
nucleus appears to have this function. In addition, Fos immunoreactiv
ity Was distributed in distinct clusters in subregions within various
brain areas in males and females. This was observed especially in the
posteromedial bed nucleus of the stria terminalis and posterodorsal me
dial amygdala, but also in the parvicellular subparafascicular nucleus
, ventromedial hypothalamic nucleus and ventral premammillary nucleus.
It appears that relatively small subunits within these nuclei seem to
be concerned with the integration of sensory and hormonal information
and may play a critical role in sexual behavior.