Bidirectional Relationships Between Tryptophan and Social Behavior in Vervet Monkeys

Enhanced central serotonergic neurotransmission appears to promote both the mood and cognitive states that in turn facilitate the expression of quiescent, calm bahaviors (Raleigh et al., 1988).

Abstract

Exogenous tryptophan induces a wide variety of behavioral effects in socially-living vervet monkeys. Tryptophan administration produces dosedependent increases in grooming, proximity to group members, and other affiliative behaviors (Raleigh et al., 1980). In stable social groups, tryptophan administration also reduces aggressive, submissive, and retaliatory aspects of agonistic behavior (McGuire and Raleigh, 1985). Pharmacological and physiological studies suggest that tryptophan's effects are mediated by central serotonin (McGuire et al., 1982; Raleigh et al., 1985). The diversity of the behavioral effects, together with the diffuse distribution of central serotonergic projections and the heterogeneity of serotonergic receptors make it unlikely that each of these distinct behavioral effects is caused by the action of serotonin alone on some final common motor pathway. Rather, enhanced central serotonergic neurotransmission appears to promote both the mood and cognitive states that in turn facilitate the expression of quiescent, calm bahaviors (Raleigh et al., 1988).