Behaviorally Conditioned Modulation of Natural Killer Cell Activity: Effects of Pre-Conditioning Manual Restraint and Apparatus Exposure

Abstract

This study investigated behaviorally conditioned modulation of natural killer cell (NK) activity. One and three trial behavioral conditioning training trial designs were examined. In addition, the influence of pre-conditioning exposure to manual restraint and the conditioning apparatus upon behaviorally conditioned natural killer cell responses was assessed. Prior to one trial training, animals were exposed to either the conditioning apparatus, manual restraint, or were undisturbed. The animals were then trained to associate the conditioned stimulus (CS) and the unconditioned stimulus (US), and later re-presented with the CS. Behaviorally conditioned animals demonstrated significantly enhanced NK cell activity, no difference in NK activity, or significantly decreased NK activity, respectively. There was also a significant interaction between the manual restraint and behavioral conditioning interventions. Animals in a three training trial design were either manually restrained daily prior to and during behavioral conditioning or were left undisturbed. In this design behavioral conditioning significantly decreased NK cell activity and manual restraint significantly increased NK cell lytic activity. These data illustrate behaviorally conditioned decreases and increases in NK cell lytic activity dependant upon the experimental design. Behaviorally conditioned NK cell activity is influenced by additional behavioral interventions (i.e. manual restraint and novelty of conditioning environment) inherent within the behavioral conditioning procedures.

Key Words:

• NK cells
• behavioral conditioning
• Poly I:C
• manual restraint
• psychoneuroimmunology