Resumo

GUTIERREZ, Carmen Inés; CARRILLO, Guillermo José  e  URBINA-GUANIPA, Omaira. Caracterización de receptores de melatonina en membranas de linfocitos caprinos. AVFT [online]. 2007, vol.26, n.1, pp.27-32. ISSN 0798-0264.

Neuroendocrine and immunological systems are structural and functionally connected. The melatonin neurohormone plays an important role in immune regulation, which is supported by the existence of melatonin specific binding sites in lymphoid cells, central nervous system and peripheral organs. Goats are domestic animals with reduced carcinoma incidence and lower infection susceptibilities. The aim of this work was to characterize the melatonin receptor in goat lymphocyte membranes obtained from peripheral blood using binding studies with [³H]iodomelatonin. Melatonin binding was time, temperature and cellular concentration dependent, also stable, reversible and saturable. Saturation assays demonstrated a high affinity binding site (Kd= 3,61+0,21 nM) and low capacity (Bmax=350,11+18,5 fmol/mg). When the animals were submitted to continuous light for 10 days, the capacity significantly increased. The results indicate that adult goats have high affinity receptors for melatonin in lymphocytes which are altered after prolonged exposure to light, confirming interaction and communication between the pineal gland and  the immune system.

Palavras-chave : melatonin; goat; lymphocyte; binding; receptor.