EN
The expression of dopamine, dopamine receptors and dopamine active transporters in peripheral lymphoid tissues and lymphocytes suggest that increased dopaminergic activity induced by cocaine may be involved in regulation of the distribution of lymphocyte subsets in the spleen. Adult male Wistar rats implanted with jugular vein catheter received cocaine hydrochloride (3 × 5 mg/kg/ml, i.v., at 30 min intervals) or saline infusions. Animals were pretreated with haloperidol (1 mg/kg/ml, i.v.) or vehicle 10 min prior to the first cocaine infusion. After each cocaine infusion the locomotor-activating effects of cocaine were measured. The spleens were collected 30 min after the third cocaine infusion and total splenocyte numbers and percentage numbers of leukocyte subpopulations were assessed using a morphological method. Three-color immunofluorescent antibody staining procedure (CD3-FITC/CD45RA-PC7/CD161A-APC and CD3-FITC/ CD4-PC7/CD8-APC) was used for determination of T, B, NK, T CD4+ and T CD8+ lymphocyte subsets. Plasma corticosterone and serum concentrations of IL-4, IFN-gamma and cocaine were assessed. In the spleen, administration of cocaine after pretreatment with haloperidol decreased numbers of splenocytes, lymphocytes and T CD4+ and B lymphocytes, significantly in comparison to rats treated with cocaine alone. The proportions between lymphocyte subsets and CD4/CD8 ratio in the spleen were not affected. Cocaine or/and haloperidol increased plasma corticosterone concentration. Serum cocaine concentration indicated the possibility of accumulation of cocaine in the applied schedule of administration. Serum concentrations of IL-4 and IFN-gamma were not altered. Haloperidol abolished locomotor response induced by cocaine infusions. In conclusion, dopaminergic activity following administration of cocaine is involved in retention of T CD4+ and B lymphocytes in the spleen of rats.