Interactive effects of cocaine and gender on thymocytes: a study of in vivo repeated cocaine exposure

Abstract

This study used a mouse model including both sexes to assess the impact of repeatcocaine exposure on the differentiation and function of T cell in thymus. Cocaine hydrochloride in0.9% saline, 5 mg or 40 mg⧹kg, was administrated by i.p. injection to C57BL⧹6 mice for 10days. Thymocytes were obtained 24 h after the 10th injection. Repeat in vivo cocaine exposureinhibited the proliferation of T lymphocytes in response to Con-A and Con-A plus anti-CD28. Theproliferation induced by IL-2 in the Con-A stimulated T blasts was attenuated in cocaine treatedmice. These effects were seen at a lower cocaine dose in female mice. The total number ofthymocytes was reduced. Although the percentage of mature thymocytes (CD4 +CD8 − and CD4 −CD8 + cells) was not altered, the absolute cell numberswere attenuated. Both percentage and absolute cell number of immature thymocytes (CD4 +CD8 +) decreased and the pre-mature (CD4 −CD8 −) cellsincreased. CD28 and CD25 expression were attenuated in Con-A stimulated thymocytes of micetreated with cocaine at 40 mg⧹kg. Interleukin 2 production was not significantly altered,however, γ-IFN production was decreased by cocaine exposure at 40 mg⧹kg. Inconclusion, cocaine exerts inhibitory effects on the function of mature thymocytes, and on thedifferentiation of thymocytes. A gender difference in response to cocaine was noted in that femalemice were more sensitive to lower dose of cocaine exposure.