MODULATION OF PROTEIN-TYROSINE PHOSPHORYLATION IN RAT INSULAR CORTEX AFTER CONDITIONED TASTE-AVERSION TRAINING

Protein tyrosine phosphorylation is a major signal transduction pathwa y involved in cellular metabolism, growth, and differentiation. Recent data indicate that tyrosine phosphorylation also plays a role in neur onal plasticity, We are using conditioned taste aversion, a fast and r obust associative learning paradigm subserved among other brain areas by the insular cortex, to investigate molecular correlates of learning and memory in the rat cortex, In conditioned taste aversion, rats lea rn to associate a novel taste (e.g., saccharin) with delayed poisoning (e.g., by LiCl injection), Here we report that after conditioned tast e aversion training, there is a rapid and marked increase in tyrosine phosphorylation of a set of proteins in the insular cortex but not in other brain areas. A major protein so modulated, of 180 kDa, is abunda nt in a membrane fraction and remains modulated for more than an hour after training, Exposure of the rats to the novel taste alone results in only a small modulation of the aforementioned proteins whereas admi nistration of the malaise-inducing agent per se has no effect, To the best of our knowledge, this is the first demonstration of modulation o f protein tyrosine phosphorylation in the brain after a behavioral exp erience.