Alterations in brain serotonin during congestive heart failure in the cardiomyopathic Syrian hamster

Serotonin and its major metabolite 5-hydroxyindoleacetic acid were measured in the pons-medulla, midbrain, posterior hypothalamus, anterior hypothalamus, thalamus, and cerebellum of cardiomyopathic hamsters and their age-matched controls during the early and terminal stages of the cardiomyopathy. During the stage of cardiac decompensation, significant increases were observed in the concentration of serotonin in pons-medulla (2.30± 0.07 vs 1.74± 0.04; P<0.001) and posterior hypothalamus (3.49± 0.04 vs 3.04± 0.11; P<0.005) and in 5-hydroxyindoleacetic acid in pons-medulla (1.42 ± 0.05 vs 0.97 ± 0.05; P< 0.001) and posterior hypothalamus (1.65± 0.02 vs 1.32 ± 0.07; P<0.001). No changes were noted in any of the brain regions of control animals. We conclude that congestive heart failure may be associated with alterations in activity of bulbohypothalamic serotonergic nerves.