The effect of methionine-enkephalin on nitric oxide release in mice is ageand gender related

Gender- and age-related differences in nitric oxide (NO) release and in res ponse to drugs of abuse has been reported in both humans and experimental a nimals. So far, we have demonstrated in vivo methionine-enkephalin- (MENK-) modulated NO release in mice. However, no data on the influence of age and gender on this immunomodulatory effect of MENK have been reported. In this study we examined the influence of age (2, 4, 8 month old mice) and gender (male and female mice) on MENK-induced NO release of mouse peritoneal macr ophages (PEMs) of the CBA strain of mice. NO release was not age but was ge nder related in that males generally produced more NO than females. The eff ect of MENK on NO release was age (demonstrated only in mature 4 and 8 mont h old mice) and gender related in that it could be observed only in female mice. Apoptotic cells that paralleled the increase of NO in MENK-treated fe male mice were, however, observed also in male mice although MENK was in ma les without effect. These data provide evidence that some immunomodulatory properties of NMNK a re age and gender related which may be relevant to the potential use of MEN K in adjuvant therapy for immunocompromised status. (C) 2001 Academic Press .