Enhanced adrenergic excitation of serotonergic dorsal raphe neurons in genetically obese rats.
Serotonergic neurons in the dorsal raphe nucleus (DRN) project to the ventromedial hypothalamus (VMH), where serotonin (5-HT) release modulates feeding. 5-HT release in the VMH is altered in genetically obese vs. lean Zucker rats. Serotonergic DRN neurons are subject to adrenergic and serotonergic neuromodulation. To determine if the difference in 5-HT release between lean and obese rats might be due to differences in these neuromodulatory pathways, we examined the effects of phenylephrine (PE) and 5-HT on serotonergic DRN neurons using current-clamp recording. Cells from lean and obese animals responded similarly to 5-HT, but cells from obese rats exhibited both a larger depolarization and increased firing rate in response to PE than did cells from lean rats. This indicates that DRN neurons of obese rats have an enhanced adrenergic drive.
Ohliger-Frerking
Patricia
P
Section of Neurobiology, Physiology, and Behavior, University of California, Davis, CA 95616, USA. frerkinp@ohsu.edu
Horowitz
John M
JM
Horwitz
Barbara A
BA
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000502:physiology; D005838:Genotype; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009765:Obesity / Q000235:genetics* / Q000503:physiopathology*; D010656:Phenylephrine / Q000494:pharmacology; D011903:Raphe Nuclei / Q000166:cytology / Q000502:physiology*; D051381:Rats; D011924:Rats, Zucker; D012701:Serotonin / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014697:Ventromedial Hypothalamic Nucleus / Q000166:cytology / Q000502:physiology
D000316:Adrenergic alpha-Agonists; D010656:Phenylephrine; D012701:Serotonin