Hyperprolactinaemia abolishes sensitivity of stria terminalis neurones to testosterone.

Hyperprolactinaemia was induced in castrated, testosterone-treated male rats using ectopic pituitary grafts under the kidney capsules. After 6 weeks the absolute refractory period of stria terminalis neurones in these animals did not differ significantly from long-term castrated rats (mean = 1.72 vs 1.69 ms) in spite of the presence of normal testosterone concentrations. Gonadally intact animals, and sham-operated castrated animals treated with testosterone, showed by comparison the characteristic significantly shorter absolute refractory period normally associated with testosterone stimulation (mean = 1.15 and 1.08 ms respectively). These results provide the first demonstration that hyperprolactinaemia can abolish central sensitivity to testosterone.