Leuprolide--a GnRH agonist--prevents restraint stress-induced immunosuppression via sex steroid-independent peripheral mechanism in mice.

Gonadotropin-releasing hormone (GnRH) and sex steroids are known to modulate the immune system. To find out whether GnRH analogue can be useful to prevent the stress-induced immunosuppression, mice were treated with leuprolide (50 microg/mouse, s.c.) 30 min prior to restraint stress and immunological parameters were studied. Leuprolide prevented stress-induced decrease in relative weights of thymus, total leukocyte count and sheep red blood cells challenged humoral and cell-mediated immune reaction. Prior administration of GnRH antagonist (10 ng/mouse) through i.c.v. route did not alter the immunological effects of leuprolide. Further, the observed effect of leuprolide remained unaffected in castrated and ovariectomized mice. Thus, the investigations revealed that leuprolide prevented stress-induced immunosuppression through a peripheral mechanism, which is independent of systemic sex steroids.