Effects of hypo and hyper-thyroidism on the content of neuropeptide glutamic acid-isoleucine (NEI) in brain areas

AYALA C; NAVARRA MORENO ML; CURTI MARÍA I; SOAJE M; VALDEZ SR; CARREÑO NB; JAHN GA; CELIS ME

Huerta Grande, Córdoba

Encuentro; RCN First Joint Meeting of the Society for Neuroscience (SAN) and the Argentine Workshop in Neuroscience (TAN); 2009

Sociedad Argentina de Investigación en Neurociencias (SAN)

NEI is a peptide derived from ppMCH that is capable of regulating the release of TSH and LH. Aim: To analyze if hypo- or hyperthyroidism can modify the content of NEI at different stages of the rat estral cycle, late pregnancy (day 19: G19 and 21: G21) and early lactation (postpartum day 2: L2), in brain areas related to reproduction. Methods: Female Wistar rats weighing between 180 and 250 g were divided into control (C) and treated (T) groups. Hypo- and hyperthyroidism were induced with PTU and T4, respectively. The studied brain areas were OVLT + AVPV (vascular organ of the lamina terminalis + anteroventral periventricular nucleus), POA (preoptic area), HLA (lateral hypothalamic area), ZI (zona incerta), PeN (periventricular nucleus), ME + Arc (median eminence + arcuate nucleus) and PP (posterior pituitary). NEI concentrations in samples were assessed by RIA. Results: Cycling females. OVLT +AVPV: the differences were observed in T, with the highest values found in T4 P12. POA (area related to sexual behaviour): the lowest values were for PTU and T4 P19h. HLA, higher concentration of NEI in C E12 that decreased in T. ZI: the pattern between C and PTU was very similar with lower values in the latter; the peptide was hardly modified in T4. No differences in C and T were observed for PeN, and were minimal in ME +Arc. PP: there was a significant increase in T E12h. Pregnant females. A significant increase of NEI was observed in pregnant rats: in OVLT + AVPV were found in T4 G19 compared to PTU, in T4 G21 compared to C and PTU, and in C L2 compared to all other groups; in POA, in PTU G21 compared to C and T4; the content of NEI in HLA for C L2 was greater than in T; increases in ZI were observed in C and T4 G19 compared to PTU, and in C L2 compared to T; PeN showed increases in T G21 compared to C; increases in ME + Arc were found in C L2 compared to PTU and T4 L2; and in PP, there were increases in T4 G21 compared to C and PTU. Conclusion: The content of NEI in different brain regions related to reproduction is modified by hypo- or hyperthyroidism in cycling, pregnant and early lactation females.