Effects of thyroid status on NEI concentration in specific brain areas related to reproduction during the estrous cycle.

AYALA C; PENNACCHIO GE; SOAJE M; CARREÑO NB; BITTENCOURT JC; JAHN GA; CELIS ME; VALDEZ SR

PEPTIDES

ELSEVIER SCIENCE INC

Lugar: Amsterdam; Año: 2013 vol. 49 p. 74 - 80

0196-9781

We previously showed that short-term hypo- and hyperthyroidism induce changes in neuropeptide glutamic-acid-isoleucine amide (NEI) concentrations in discrete brain areas in male rats. To investigate the possible effects of hypo- and hyperthyroidism on NEI concentrations mainly in hypothalamic areas related to reproduction and behavior, female rats were sacrificed at different days of the estrous cycle. Circulating luteinizing hormone (LH), estradiol and progesterone concentrations were measured in control, hypothyroid (hypoT, treated with PTU during 7-9 days) and hyperthyroid (hyperT, L-T4 during 4-7 days) animals. Both treatments blunted the LH surge. Hypo- and hyperthyroidism increased estradiol concentrations during proestrus afternoon (P-PM), although hypoT rats showed lower values compared to control during proestrus morning (P-AM). Progesterone levels were higher in all groups at P-PM and in the hyperT during diestrus morning (D2). NEI concentrations were lower in hypoT rats during the estrous cycle except in estrus (E) in the peduncular part of the lateral hypothalamus (PLH). They were also reduced by both treatments in the perifornical part of the lateral hypothalamus (PeFLH) during P-PM. Hypothyroidism led to higher NEI concentrations during P-PM in the organum vasculosum of the lamina terminalis and anteroventral periventricular nucleus (OVLT + AVPV). The present results indicate that NEI concentration is regulated in a complex manner by hypo and hyperthyroidism in the different areas studied, suggesting acorrelation between NEI values and the variations of gonadal steroidlevels during estrous cycle. These changes could be, in part, responsiblefor the alterations observed in the hypothalamic-pituitary-gonadal axisin these pathologies.