Dehydroepiandrosterone regulation of prolactin gene expression in the anterior pituitary does not depend on galanin induction.
OBJECTIVE
The effects of dehydroepiandrosterone (DHEA) on galanin (GAL) and prolactin (PRL) mRNA expression in the anterior pituitary of Fischer 344 rats were studied, taking in consideration that: (1) DHEA is an androgen with estrogenic activity on pituitary lactotrophs; (2) estrogens induce prolactinomas in Fischer 344 rats; and (3) GAL has been considered the main mediator of estrogen-induced lactotroph proliferation.


METHODS
Female rats were ovariectomized and used as controls or treated during 2 weeks with DHEA (500 mg/kg/day or 5 mg/kg/day or 50 mg/kg/day) or estradiol (E2, 50 microg/kg/day), as a positive control for pituitary growth and GAL induction. GAL and PRL mRNA expression were studied by in situ hybridization.


RESULTS
Both DHEA and E2 induced PRL mRNA synthesis. However, DHEA neither produced pituitary enlargement nor GAL induction, in contrast to E2.


CONCLUSIONS
Our results shows that GAL is not involved in the estrogenic activity of DHEA on pituitary lactotrophs, and suggest that DHEA effects are exerted directly on the PRL gene or through another mechanism(s) not related to GAL.
Laboratorio de Bioquímica Neuroendócrina, Instituto de Biología y Medicina Experimental, UBA-CONICET, Buenos Aires, Argentina. pirolig@mail.rockefeller.edu
Gerardo G
GG
Piroli
Luciana
L
Pietranera
Claudia A
CA
Grillo
Alejandro F
AF
De Nicola
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D015197:Carcinogenicity Tests; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D019004:Galanin / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000502:physiology*; D011388:Prolactin / Q000097:blood / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344
D000276:Adjuvants, Immunologic; D012333:RNA, Messenger; D003687:Dehydroepiandrosterone; D004958:Estradiol; D019004:Galanin; D011388:Prolactin