INVESTIGADORES
CARON Ruben Walter
artículos
Título:
ESTROGEN INHIBITS TUBEROINFUNDIBULAR DOPAMINERGIC NEURONS BUT DOES
Autor/es:
MOREL, G. R.; CARÓN, R.W.; CONSOLE, G.M.; SOAJE, M. I.; SOSA, Y.E.; RODRÍGUEZ, S.S.; JAHN, G.A.; GOYA, R. G
Revista:
BRAIN RESEARCH BULLETIN
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Año: 2009 vol. 80 p. 347 - 352
ISSN:
0361-9230
Resumen:
2
Abstract
Dopaminergic neurons of the hypothalamic tuberoinfundibular dopaminergic (TIDA) system
exert a tonic inhibitory control on prolactin (PRL) secretion whereas estrogen, known to
inhibit TIDA neuron function, has been postulated to be toxic to TIDA neurons when it is
chronically high. In order to determine whether estrogen in high doses can cause permanent
damage to TIDA function, we submitted young female rats to continued high doses of
estrogen administered, either centrally (intrahypothalamic estrogen implants) or peripherally
(subcutaneous estrogen implants or weekly intramuscular (i.m.) injections for 7 weeks),
subsequently withdrawing the steroid and observing the evolution of lactotrophes, serum PRL
and TIDA neurons. Serum PRL was measured by radioimmunoassay whereas tyrosine
hydroxylase positive (TH+) neurons and PRL cells were morphometrically assessed in
sections of fixed hypothalami and pituitaries, respectively. After 30 days, hypothalamic
estrogen implants induced a significant increase in serum PRL, whereas TH+ neurons were
not detectable in the arcuate-periventricular hypothalamic (ARC) region of estrogen-implanted
rats. Removal of implants on day 30 restored TH expression in the ARC and
brought serum PRL back to basal levels 30 days after estrogen withdrawal. Subcutaneous or
i.m. administration of estrogen for 7 weeks induced a marked hyperprolactinemia. However,
30 weeks after estrogen withdrawal, TH neuron numbers in the ARC were back to normal and
serum PRL returned to basal levels. After peripheral but not central estrogen withdrawal,
pituitary weight and lactotrophic cell numbers remained slightly increased. Our data suggest
that estrogen even at high doses, does not cause permanent damage to TIDA neurons.
prolactin