Mild hyperthyroidism affects prolactin secretion induced by acute stress in lactating rats

NEIRA FLAVIA JUDITH; SÁNCHEZ MARÍA BELÉN; MICHEL MARÍA CECILIA; TRONCOSO MARIANA; PIETROBON ELISA OLIVIA; SOAJE MARTA; MACKERN OBERTI JUAN PABLO; JAHN GRACIELA ALMA; VALDEZ SUSANA RUTH

Congreso; XXXIX Reunión Científica Anual Sociedad de Biología de Cuyo; 2021

Hyperthyroidism (HyperT) has higher incidence in women than in men and can cause reproductive disorders affecting lactation. Pregnancy and lactation are regulated by intricate central neuroendocrine mechanisms present in areas such as the medial basal hypothalamus (MBH), the main neuronal group that regulates PRL secretion. PRL has various functions at the central level and its receptor is expressed in different brain regions that modulate the response to stress. We evaluated the effect of mild HyperT on PRL release in response to acute stress in lactating rats. HyperT was induced with T4 (0.1mg /kg/day, s.c.) a dose of that allows the maintenance of lactation. Control (Con) and HyperT female Wistar rats were bled from the tail vein during the 2 min ether exposure (s1) and 5 min after ether exposure (s2). We analyzed serum prolactin levels in day 19 of gestation (G19), 2 (L2) and 12 (L12) of lactation. To explore the neuroendocrine mechanisms of PRL release in lactation, we also determined by RT-qPCR the expression of thyroid receptor (TR), the long isoform of the prolactin receptor (PRLRl), members of the PRL signaling pathway (STAT5b; CIS; SOCS), progesterone receptor (PR), estrogen receptor (ER) and glucocorticoid receptor (GR) in MBH of rats in G19, L2 and L12 of lactation in non-stressed Con and HyperT groups. In G19 acute stress induced PRL release in HiperT (P0.05), while in Con group no response was observed. In L2 no response to stress was observed in both Con and HiperT rats, but basal, s1 and s2 PRL levels are lower in HyperT compared to Con rats (P0.05, P0.05 and P, respectively). In L12 PRL release decreased in HyperT while stress increased levels in Con rats (P0.05. In MBH the main changes in expression TRs were observed in the β isoform. TRβ1 increased on L12 compared to L2 andG19 in the HyperT group (P