Temporal Synergism of 5-HTP and L-DOPA in the Water Vole,Arvicola terrestris: Behavioral and Physiological Effects

A laboratory population of water voles, Arvicola terrestris, was tested in the late winter for its behavioral and physiological responses to 5-HTP and L-DOPA injected daily in various time relations. The experiments were designed according to the concept of temporal synergism developed by Albert H. Meier and colleagues. The parameters studied were: (1) The circadian rhythm of body temperature. (2) The circadian rhythm of plasma glucocorticoids. (3) Body weight. (4) The thermoregulatory response to norepinephrine injections. (5) Various agonistic and emotional behaviors. Even though the water voles received the same total doses of neurotransmitter precursor, their responses in general depended on the specific temporal relation of the injection times. More detailed research is needed to document more fully the role of temporal synergism in this species.