Changes in the content of neuropeptide glutamic acid isoleucine (NEI) in different brain areas secondary to the induction of hypo- and hyperthyroidism in adult male rats

AYALA CAROLINA; NAVARRA MORERO ML; SOAJE MARTA; VALDEZ SUSANA R; CARREÑO NORMA B; JAHN, GRACIELA A; CELIS

Rouen

Congreso; 7th International Congress of Neuroendocrinology; 2010

Introduction: NEI is a linear 13-aminoacids neuropeptide derived from pp-MCH. NEI is able to inhibit TRH release in mediobasal hypothalamus and to stimulate LH release in hypothalamus and pituitary. Aim: To study whether hypo- and/or hyperthyroidism may change the content of the peptide in different brain areas. Materials and Methods: Adult male Wistar rats divided into control (CTR) and treated (T): hypothyroid animals (PTU) received PTU 0.1 g/l in drinking water during 8th days, hyperthyroid induced group (T4) received L-T4 250 μg/kg sc daily for 4 days. Animals were sacrificed in the morning (M) and afternoon (A). Trunk blood was collected; pineal gland, brain and posterior pituitary (PP) were obtained. Coronal brain slices of 1 mm were serially sectioned and the areas of interest were collected by microdissection. NEI content was determined by radioimmunoassay (RIA). Statistics: one-way ANOVA followed by Tukey’s test (Tukey’s HDS), significance p < 0.05. Results: anteroventral periventricular nucleus: higher values in PTU at M; preoptic area: increased content in T4 at M; lateral hypotalamic area+perifornix: lower amount in T4 at M; zona incerta+IHy: higher values in T4 at M; median eminence+arcuate nucleus: higher values of the peptide at M in T4; PP: higher content of NEI in T4 at M. Discussion: The higher amount of NEI in the T4 group may allow as to propose that higher levels of thyroid hormones may induce an increase in NEI content, possibly by different pathways.