EN
High frequency stimulation (HFS) of the subthalamic nucleus (STN) is a surgical therapy for improving of motor symptoms in Parkinson’s disease. In this study, we assessed the HFS effects on cytometric analysis of the peripheral blood lymphocytes (T, B, NK, T helper, T cytotoxic) in freely moving hemiparkinsonian rats. Before unilateral lesion of the right substantia nigra pars compacta (6-hydroxydopamine), all rats were divided into two behavioral groups: high-HR and low-LR responders in novelty test. As compared to the sham controls, HFS of STN signifi cantly increases NK cell percentage number (25.86 ± 9.68% vs. 18.79 ± 5.63%, P<0.05). In contrast, signifi cantly (P<0.05) lower B lymphocytes level in stimulated (18.86 ± 3.91%) then sham group (22.80 ± 4.63%) was observed. These general changes in NK and B lymphocyte numbers were refl ected in HR stimulated animals (31.08 ± 7.19% vs. 20.44 ± 5.65% for NK cells number and 17.67 ± 2.57% vs. 23.23 ± 3.37% for B lymphocyte, stimulated vs controls, respectively, P<0.01). On the other hand, signifi - cantly lower T lymphocyte level in LR stimulated animals in comparison to LR controls was found (38.32 ± 4.18% vs. 45.91 ± 5.68%). Moreover, signifi cant differences between stimulated HRS and LRS in the NK and T cytotoxic percentages were found (31.08 ± 7.19% vs. 17.63 ± 6.74%, P<0.05; 8.46 ± 1.83% vs. 12.29 ± 1.76%, P<0.01). The results emphasize the importance of individual differences in reactivity to novelty on immune response to HFS of STN.