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

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

PEPTIDES

ELSEVIER SCIENCE INC

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

0196-9781

tWe previously showed that short-term hypo- and hyperthyroidism induce changes in neuropeptideglutamic-acid-isoleucine-amide (NEI) concentrations in discrete brain areas in male rats. To investigatethe possible effects of hypo- and hyperthyroidism on NEI concentrations mainly in hypothalamic areasrelated 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 con-trol, hypothyroid (hypoT, treated with PTU during 7?9 days) and hyperthyroid (hyperT, l-T4during 4?7days) animals. Both treatments blunted the LH surge. Hypo- and hyperthyroidism increased estradiolconcentrations during proestrus afternoon (P-PM), although hypoT rats showed lower values comparedto control during proestrus morning (P-AM). Progesterone levels were higher in all groups at P-PM andin the hyperT during diestrus morning (D2). NEI concentrations were lower in hypoT rats during theestrous cycle except in estrus (E) in the peduncular part of the lateral hypothalamus (PLH). They werealso 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 thelamina terminalis and anteroventral periventricular nucleus (OVLT + AVPV). The present results indicatethat NEI concentration is regulated in a complex manner by hypo- and hyperthyroidism in the differentareas studied, suggesting a correlation between NEI values and the variations of gonadal steroid levelsduring estrous cycle. These changes could be, in part, responsible for the alterations observed in thehypothalamic?pituitary?gonadal axis in these pathologies.We previously showed that short-term hypo- and hyperthyroidism induce changes in neuropeptideglutamic-acid-isoleucine-amide (NEI) concentrations in discrete brain areas in male rats. To investigatethe possible effects of hypo- and hyperthyroidism on NEI concentrations mainly in hypothalamic areasrelated 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 con-trol, hypothyroid (hypoT, treated with PTU during 7?9 days) and hyperthyroid (hyperT, l-T4during 4?7days) animals. Both treatments blunted the LH surge. Hypo- and hyperthyroidism increased estradiolconcentrations during proestrus afternoon (P-PM), although hypoT rats showed lower values comparedto control during proestrus morning (P-AM). Progesterone levels were higher in all groups at P-PM andin the hyperT during diestrus morning (D2). NEI concentrations were lower in hypoT rats during theestrous cycle except in estrus (E) in the peduncular part of the lateral hypothalamus (PLH). They werealso 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 thelamina terminalis and anteroventral periventricular nucleus (OVLT + AVPV). The present results indicatethat NEI concentration is regulated in a complex manner by hypo- and hyperthyroidism in the differentareas studied, suggesting a correlation between NEI values and the variations of gonadal steroid levelsduring estrous cycle. These changes could be, in part, responsible for the alterations observed in thehypothalamic?pituitary?gonadal axis in these pathologies.