Effects of amphetamine on NK-related cytotoxicity in rats differing in locomotor reactivity and social position.

The effect of i.p. administration of 1mg/kg of amphetamine (AMPH) on natural killer cells cytotoxicity (NKCC) and number of large granular lymphocytes (LGL-NK) together with plasma corticosterone (CORT) level and WBC was evaluated in male Wistar rats differing in two behavioral features: locomotor reactivity to novelty (high, HR and low, LR responders) and social position (dominants, D and subordinates, S). In the majority of animals AMPH evoked (30 min after administration) an increase in NKCC and LGL (NK) number accompanied by lymphopenia, neutrocytosis, monocytosis, and an increase in CORT level. Changes in NKCC (LU20) showed substantial individual variability: in HR group approximately 513Delta%, p <0.01 (relative to the control); LR group approximately 56Delta%, p >.05; D group approximately 441Delta%, p >0.001; S group approximately 216Delta%, p >0.05; HR/D group approximately 643Delta%, p <.001; HR/S group approximately 414Delta%, p <.001; LR/D group approximately 191Delta%, p >.05; and LR/S group approximately -19Delta%, p .05. The increase in CORT level, lymphopenia, and neutrocytosis indicated a stress-like reaction to AMPH. No significant correlation between NKCC and CORT level was found. The results obtained indicate that AMPH can evoke an increase in NK-related cytotoxic activity quantitatively related to high behavioral reactivity to novelty and social dominance, however NKCC is not related to the AMPH-induced CORT changes.