Neonatal antiandrogens and organization of behavioral sex differences in the rat (Rattus norvegicus)

Neonu/a/ antiandrogens and organi::ution of' behavioral se.r c/Uferences i11 the ml (Rattus norvegicus).The role or androgens in the masculinization and later activation of socio­ sexual hehavior. was studied in the following experimental groups or Wistar rats: control males (MAL): peripuberLally castrated males (GON): peripubertally castrated males supplied with testosterone propionate in ,1dulthood (GTP): and males postnatally injected with cyproterone acetate. gonadectomized and supplied with testosterone propionate (CGTP). The observed clecrc,1se of sexual perrormance in animals neonatally treated with cyproterone acetate (CPA) should he a consequence of the reduced neonatal binding of testosterone (T) or 5adihydrotestosterone (DHT) lo androgen receptors provoked by the antiandrogen. On the contrary. animals treated with CPJ\ showed higher levels or sexual motivation (sniff, partner grooming. anogenital sniff and mount): neonatal CPA seems to increase the sensibility to testosterone in adulthood. perh,1ps potentiating the aromatization of androgens by blocking its direct actions. Finally. the reduced frequency and latency of the studied patterns in castrated rats suggest that the presence orT in adulthood is necessary for the activation of socio-sexual and mating behavior. Howevn. testosterone propionate (TP) supplementation in gonadectomized animals did not completely recover the beha\'ior of the control males. suggesting that T probably can play an organizational effect upon certain patterns during puberty.