Effects of sexual interactions with a male on Fos-like immunoreactivity inthe female quail brain

Sexual interactions can cause changes in plasma hormone levels and activate immediate early genes within the mammalian brain, There are marked anatomi cal differences between the regions activated that relate directly to the s exual specific behaviour and neuroendocrinology of each sex. The aim of thi s study was to determine if such a sexual dimorphism exists in birds by exa mining the brain regions stimulated in adult virgin female Japanese quail ( Coturnix japonica) during sexual behaviour and comparing this to previously reported data concerning males. Female quail were allowed to freely intera ct with adult males and both female and male sexual behaviour was recorded. Contrary to previous findings in male quail, no significant induction of F os-like immunoreactive (FLI) cells was observed following sexual interactio ns in the preoptic area of females; this area is fundamentally involved in the control of male-type copulatory behaviour, Sexual interactions signific antly induced FLI cells in the hyperstriatum ventrale, the part of the arch istriatum just lateral to the anterior commissure, and the nucleus intercol licularis, Moreover, prominent activation was detected throughout most of t he ventromedial nucleus of the hypothalamus, a region reported to be rich i n oestrogen receptors, FLI induction was not a consequence of sexual behavi our induced changes in luteinizing hormone (LH) as plasma LH levels were un altered. Instead, brain activation must be a consequence of copulation-asso ciated somatosensory inputs or direct stimuli originating from the male. Ma le quail, like the majority of other birds, lack an intromittant organ (pen is) so that the somatosensory inputs to the female are rather different fro m those in mammals; the precise nature of these inputs is yet to be determi ned.