RESUMO
In this work we demonstrate that the stress-induced reduction in bone marrow granulocyte-macrophage colonies, reported previously from our laboratory, is prevented by both the inhibition of the hypothalamic-pituitary-adrenal axis (HPAA) and the blockage of opioid receptors. The inhibition of the HPAA was obtained through the administration of dexamethasone (1 mg/kg). The blockage of opioid receptors was done in two ways, by the administration of naltrexone (8 mg/kg) and induction of tolerance to morphine. On the other hand, no protection was observed in metyrapone treated rats. We suggest that the two physiological systems, opioid and HPAA, mediate the stress-induced myelosuppression and that these systems may function independently in this particular situation.
Assuntos
Leucopoese/fisiologia , Estresse Fisiológico/fisiopatologia , Animais , Células da Medula Óssea/citologia , Dexametasona/farmacologia , Feminino , Glucocorticoides/farmacologia , Granulócitos/citologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Sistema Hipotálamo-Hipofisário/fisiologia , Leucopoese/efeitos dos fármacos , Macrófagos/citologia , Naltrexona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Sistema Hipófise-Suprarrenal/efeitos dos fármacos , Sistema Hipófise-Suprarrenal/fisiologia , Ratos , Ratos WistarRESUMO
Bone marrow cell responsiveness to hematopoietic growth factors was investigated in rats only confined or experiencing inescapable, escapable shocks or no electric shock. The results demonstrated a significant reduction in the number of granulocyte-macrophage precursors in the bone marrow of confined rats and of rats exposed to inescapable shocks. The reversibility of this mielossupressive response was seen in both groups and occurred first in the confined animals. No changes were observed in the group submitted to escapable shocks when compared to controls.