Changes in the responsiveness of prolactin secretion to dopaminergic blockade and TRH stimulation throughout sexual maturation in men.
The pituitary prolactin (PRL) response to domperidone (DOM; a dopaminergic antagonist) and TRH administration in human males during different stages of sexual maturation was investigated. Dopaminergic blockade caused an immediate and significant PRL release in all subjects, regardless of the stage of pubertal development. Even though the mean values of peak PRL levels, magnitude of PRL response (delta PRL) and areas under the PRL curve were not significantly different among the different groups, all these parameters showed a clear tendency to increase in parallel to the stage of pubertal development, as indicated by significant positive correlations between age and pubertal stage of the subjects and the magnitude of their PRL response to DOM (r = 0.661, p less than 0.01 and r = 0.536, p = 0.01, respectively). Significant positive correlations also were found between the serum sex steroid hormone concentrations and the PRL response to dopaminergic blockade (r = 0.774, p = 0.02 and r = 0.554, p = 0.01, respectively). In contrast to these findings, no significant differences or tendencies were detected in the PRL responses to TRH among the different subject groups. The different patterns of PRL response to DOM and TRH throughout male puberty might be due to differences in pituitary thresholds for sex steroids between the dopamine- and TRH-dependent intracellular pools.
Ulloa-Aguirre
A
A
Department of Reproductive Biology, National Institute of Nutrition S. Zubirán, México.
Tarrasó
J
J
Mendez
J P
JP
Garza-Flores
J
J
Díaz-Sanchez
V
V
Perez-Palacios
G
G
D000293:Adolescent; D000328:Adult; D002648:Child; D004294:Domperidone; D004298:Dopamine / Q000502:physiology*; D006801:Humans; D008297:Male; D011388:Prolactin / Q000097:blood*; D011627:Puberty / Q000502:physiology*; D011954:Receptors, Dopamine / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology*; D013739:Testosterone / Q000097:blood; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology*
D011954:Receptors, Dopamine; D013739:Testosterone; D004294:Domperidone; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D004298:Dopamine