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 less than 0.001) and posterior hypothalamus (3.49 +/- 0.04 vs. 3.04 +/- 0.11; P less than 0.005) and in 5-hydroxyindoleacetic acid in pons-medulla (1.42 +/- 0.05 vs 0.97 +/- 0.05; P less than 0.001) and posterior hypothalamus (1.65 +/- 0.02 vs 1.32 +/- 0.07; P less than 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.