Effect of ovariectomy on PRL and hypothalamic expression of tyrosine hydroxylase (TH), receptors and PRL signaling molecules

CAMPO VERDE ARBOCCÓ FIORELLA; BONAFEDE M M; VALDEZ, SUSANA R; SOAJE MARTA; JAHN, GRACIELA A

Mendoza

Congreso; Sociedad de Biología de Cuyo; 2010

Sociedad de Biología de Cuyo y Secretaría de Ciencia, Técnica y Posgrado de UNCuyo.

@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; } Ovariectomy (OVX) does not impair suckling induced PRL release although ovarian hormones play a key role in the hypothalamic regulation of prolactin secretion by dopaminergic neurons. To investigate the effect of OVX on days 2 (L2) or 10 (L10) of lactation on ovarian hormone receptors and PRL signaling mechanisms we determined by real time PCR the hypothalamic expression of TH. receptors for E2 (ER), PRL (PRLR) and P4 (PR), STAT5b (mediator of PRL signaling) and SOCS3 (suppressor of PRL signaling) on rats on day 12 of lactation. OVX on L2 or L10 had similar effects, lowering the expression of PRLR (Control 235±29 p<0.05 vs. OVXL2 126±15 and OVXL10 108±6), SOCS3 (Control 15.0±2.6 p<0.05 vs. OVXL2 9.8±1.1 and OVXL10 7.7±0.4) and B isoform of PR (Control 42±8 p<0.05 vs. OVXL2 19±3 and OVXL10 14±1), without affecting TH, ERa and total PR (A + B isoforms). These results suggest that E2 deprivation by OVX represses PRLR, PRB and SOCS3 expression and that the decreased SOCS3 expression compensates for the fall in PRLR, maintaining constant the TH expression and dopaminergic neuron transmission (regulated by the short-loop PRL negative feedback mechanism) and thereby suckling induced PRL secretion. This new equilibrium is established in a short time, since OVX performed on L2 or L10 had similar effects.