Influence of small mechanical head injuries on peripheral blood natural killer cytotoxicity (NKCC) in rats.

Many neurophysiological experiments and some human's brain tissue stimulatory therapies require surgery intervention, which results in small mechanical skull and brain tissue injuries. Additionally, these procedures need some local or short general anaesthesia, which is not neutral for immune system action. Clinical data unambiguously shows that severe head and brain injuries and anaesthesia can suppress immunity. The aim of the present study was to investigate the influence of small mechanical skull and brain tissue injuries, accompanied by electrode fixation for experimental or therapeutic brain tissue stimulation, on peripheral blood natural killer cytotoxicity (NKCC) assessed in a 4h standard cytotoxic test. Additionally, we assessed a number of leukocytes, lymphocytes and large granular lymphocytes (LGL), which are NK cell subset and plasma corticosterone concentration. The results showed that small mechanical skull and meninges injuries or alone-administered Nembutal did not evoke any significant changes as those caused by electrode placement 4.2 mm below the skull surface. Deeper electrode fixation, 6.1; 7.6 and 8.4 mm below the skull surface, significantly increased NKCC (p < 0.05) and LGL number (p < 0.05) on the 3rd day after the electrode placement. Moreover, the results showed that some small brain tissue injuries could transiently influence the number of LGL and NKCC.