Effects of Lysine-Vasopressin on Spontaneous Behavior and Learning In Appetitive Tasks in the Rat

Abstract

As a result of the demonstration by de Wied (1966) that pitressin, a neurohypophyseal extract, increased resistance to extinction of avoidance tasks in the rat, it was suggested that vasopressin may play an important role in memory processes. Several experimental findings have lent empirical support to this notion. The existing evidence can be summarized as follows:

• 1) Injections of vasopressin have been shown to alleviate memory impairments caused by different kinds of experimental or natural disruptive events such as hypophysectomy (de Wied, 1969, Bohus et al.,1975), lack of vasopressin release due to hereditary hypothalamic diabetes insipidus (Bohus et al., 1977) or the administration of amnestic agents such as puromycin (Walter et al., 1975), pentylenetetrazol (Bookin and Pfeifer, 1977), C02 or ECS (Rigter et al., 1974);

• 2) Post-training administration of vasopressin has been shown to facilitate retention of several aversive tasks (de Wied et al., 1984);

• 3) The inactivation of endogenous vasopressin by a specific anti-serum injected intraventricularly or intrahippocampally results in impaired avoidance performance (Van Wimmersma-Greidanus et al.,1976). Taken together, existing evidence is in support of a “mnemoactive” role of vasopressin (Gold and Zornetzer, 1983) and suggests that this peptide might have clinical applications in the treatment of amnesic syndroms in humans. However, Jolies (1983) has pointed out that an evaluation of clinical efficiency of vasopressin is difficult since both positive and negative results have been obtained.