EVALUATION OF IMMUNE PARAMETERS AND LYMPHOCYTE-PRODUCTION OF PROLACTIN-IMMUNOREACTIVE PROTEINS AFTER CHRONIC ADMINISTRATION OF COCAINE TO PREGNANT RATS

This study examined the effect of chronic cocaine exposure on selected immune parameters in pregnant rats. Cocaine hydrochloride, 60 mg/kg, was administered by i.p. injection as a divided daily dose on gestatio n days 8 to 19. This cocaine treatment regimen did not result in any c hange in maternal body weight, spleen and thymus body weight ratios or lymphocyte recovery from these organs. Cocaine treatment had no effec t on the plasma levels of prolactin, growth hormone and insulin-like g rowth factor-1; hormones with immunoregulatory potential. In contrast, the plasma immunoglobulin G concentration in cocaine-treated animals was 48% higher (P < .05) than in control animals. Spleen lymphocytes a nd thymocytes were isolated and evaluated for their proliferative resp onses in vitro to a panel of T and B cell mitogens. Lymphocytes from c ocaine-treated animals showed no significant differences in proliferat ive responses to concanavalin A (conA), phytohemagglutinin, pokeweed m itogen, interleukin-2 or lipopolysaccharide. The ability of conA-stimu lated spleen lymphocytes to synthesize and secrete prolactin-immunorea ctive proteins was further assessed by Western immunoblotting. We foun d that conA-stimulated spleen lymphocytes from cocaine-treated animals showed significantly decreased levels of intracellular and secreted 4 4,000-mw prolactin-immunoreactive proteins. In contrast, conA-stimulat ed spleen lymphocytes from control and cocaine-treated groups secreted equivalent amounts of the cytokine interleukin-2. In conclusion, chro nic administration of cocaine to female rats during pregnancy signific antly altered serum immunoglobulin G levels and lymphocyte production of prolactin-immunoreactive proteins in the absence of changes in lymp hocyte proliferation in response to mitogens.