- Mild-tail-pinch induces a syndrome of eating, gnawing and licking behavior in rats in the presence of food. Detailed behavioral, pharmacological and biochemical analyses of this phenomenon resulted in the following conclusions. (1) This is an unusually reliable phenomenon, demonstrable in each of more than 200 animals tested. (2) Eating is by far the predominant response to tail-pinch. (3) Tail-pinch behavior is critically dependent on the nigrostriatal dopamine system. (4) There are striking pharmacological parallels between tail-pinch behavior and schizophrenia.