Effects of estivation on the levels of biogenic amines and related compounds in the ganglia, the auricle, and the ventricle of the heart of the pulmonate land snailHelix lucorum (L): Evidence for physiological roles of serotonin and dopamine in the control of heart function during estivation

Abstract

The contents of biogenic amines and related compounds were measured by high perfomance liquid chromatography with electrochemical detection (HPLC-ED) in extracts of ganglia and of the auricle and the ventricle of the heart of active land snails Helix lucorum and were also measured after 15 days, 20 days, 1 month, 2 months, and 3 months of estivation. The chromatograms obtained from ganglia samples from active and estivating animals revealed the presence of dopamine (DA) and serotonin (5-HT). In addition, small peaks corresponded to analytes with retention time similar to that of 5-HTP, an immediate precursor of 5-HT, and to that of 3,4-dihydroxy phenylacetic acid (DOPAC), a metabolite of DA, were also observed. On the contrary, 5HIAA, a metabolite of 5-HT, was observed only in chromatograms obtained from ganglia samples of estivating animals. DA and 5-HT were the only biogenic amines that were always detectable in the auricle and the ventricle of both active and estivating snails. Over the course of estivation, significant fluctuations in the content of DOPAC were observed in the ganglia. Significant fluctuations of 5-HT content were also observed in the ventricles and the auricles during estivation, whereas the most remarkable changes in the content of DA were observed in the ventricles. The periodic changes in the content of DOPAC and of 5HIAA in the ganglia and the fluctuations of the DA and 5-HT content in the heart indicate that heart activity is modulated periodically by serotonergic and dopaminergic fibres in H. Lucorum during estivation. J. Exp. Zool. 283:137–146, 1999. © 1999 Wiley-Liss, Inc.