CONICET | Buscador de Institutos y Recursos Humanos

INVESTIGADORES

VALDEZ susana Ruth

datos académicos

artículos

capítulos de libros

congresos y reuniones científicas

Título:

REGULATION OF THYROID HORMONE RECEPTORS BY SUCKLING IN RATS WITH NORMAL OR DEFICIENT LACTATION

Autor/es:

PENNACCHIO GISELA E; NEIRA FLAVIA J; VALDEZ SUSANA R; JAHN GRACIELA A; SOAJE MARTA

Lugar:

Buenos Aires

Reunión:

Congreso; LXII Reunión Anual de la Sociedad de Investigación Clínica; 2017

Institución organizadora:

SAIC, SAIB, SAI, SAFE, SAA, SAB, SAFIS, SAA, SAP.

Resumen:

During lactation, sustainedhyperprolactinemia is maintained by the suckling stimulus and decreasedhypothalamic sensitivity to prolactin (PRL) negative feedback, that maintains areduced dopaminergic tone. OFA (hr/hr) rats, derived from the Sprague Dawley(SD) strain have deficient lactation, high hypothalamic dopaminergic tone and ablockade in suckling induced PRL release. Hyperthyroidrats also have deficientlactation, caused by increased hypothalamic sensitivity to PRL negativefeedback that leads to a partial blockade in suckling induced PRL release.Thus, both groups show elevated dopaminergic tone responsible for the decreasedPRL release and lactation failure. This evidence suggests that thyroid hormonesmay be also involved in prolactin regulation during lactation. We investigatedthe changes in hypothalamic thyroid hormone receptors (TR) expression inresponse to the suckling stimulus in OFA rats compared to SD rats (normallactation). Using real time quantitative RTPCR, we measured the changes inhypothalamic mRNA expresión of TRβ isoforms 1 and 2 and TRα isoforms 1 and 2,in mid-lactating OFA and SD rats, continuously suckled (CL), separated fromtheir pups for 12 h (Sep), or separated and subsequently suckled during 2 (S2)or 4 (S4) h. We also determined serum PRL levels by RIA and litter weight gain.After suckling, PRL release and litter weight gain were higher (p<0.05) inSD than OFA rats. In SD rats, separation had no effect, but S2 and S4 inducedincreases in all TR isoforms mRNAs (p<0.01). OFA CL and Sep rats had highervalues of all TR isoforms compared with SD rats (p<0.05), and they decreasedafter suckling to lower values (p<0.05) than in SD rats for TRβ1, TRα1 andTRα2. These results show that lactating OFA rats have differential hypothalamicTRs expression patterns in response to suckling, suggesting that they may beinvolved in the regulation of the negative PRL feedback mechanism present inneuroendocrinedopaminergic neurons.

enviar mensaje