Effects of hypothalamic implants of gonadal steroids on courtship behaviour in Barbary doves (Streptopelia risoria).

Abstract

SUMMARY To determine whether the display of male courtship behaviour depends on the action of androgen on discrete areas of the brain, single crystalline implants of testosterone propionate (TP) (mean weight 40 μg) were positioned unilaterally in the brains of castrated male Barbary doves. Implants in the preoptic, anterior hypothalamic and lateral hypothalamic areas induced the full courtship display consisting of chasing, bowing and nestsoliciting. None of these behaviour patterns was re-established at precastration levels measured in terms of duration of display. Durations of courtship displayed by implanted males were similar to those induced by daily intramuscular injections of TP (300 μg/day × 15) into castrated birds. The effectiveness of implants of TP into other regions of the brain could be related to their proximity to the preoptic and anterior hypothalamic regions. There were marked deficits in the pattern of courtship of castrated doves with implants in areas adjacent to the preoptic and anterior hypothalamic regions — the neostriatum intermediale, the area basalis, and posterior hypothalamus; implants more distantly placed in the paleostriatum primitivum and lateral forebrain bundle area did not induce courtship behaviour. Cholesterol implants (59 μg) and blank implant tubing in the preoptic and anterior hypothalamic areas did not affect behaviour. The results obtained were not specific for TP implants; chasing and nest-soliciting displays were also induced by either testosterone implants (51 μg) or oestradiol-17β monobenzoate implants (47 μg). In both cases, the courtship display lacked bowing. It is concluded that the preoptic and anterior hypothalamic areas are directly sensitive to testosterone and that these areas are associated with the control of courtship behaviour.