Protein kinase C in nucleus parabrachialis: effect of drugs inducing conditioned taste aversion

A method for the dissection of the nucleus parabrachialis (NPB) from the coronal sections of frozen rat brain is described. The protein kinase C (PKC) activity was determined in the cytosol and particulate fractions of the pooled samples of the nucleus. The effect of the i.p. administration of the conditioned taste aversion-inducing agents LiCl and CuSO4 on PKC in the NPB and visual cortex (VC) was tested. 1 h after the LiCl injection, the portion of the membrane-bound PKC was increased by 23% (P < 0.01) above the level found after the saline injection. CuSO4 produced a 19% increase. Since the PKC activity in the cytosol declined, it is likely that the translocation of the enzyme took place. No changes in the PKC distribution in the VC samples could be detected. The results support the idea that the PKC translocation is not directly induced by the tested substances but that it rather reflects changes in the activity of the visceral system.