Hypothalamic melanocortin system regulates sympathetic nerve activity in brown adipose tissue.
To clarify the neuronal mechanism of the hypothalamic melanocortin system in regulating energy metabolism, we investigated the effects of centrally administered alpha-melanocyte-stimulating hormone (alpha-MSH) and agouti-related protein (AGRP), an agonist and an antagonist for the melanocortin 4 receptor (MC4-R), respectively, on the activity of sympathetic nerves innervating brown adipose tissue (BAT) and on BAT temperature. A bolus infusion of alpha-MSH (1 nmol) into the third cerebral ventricle (i3vt) significantly increased sympathetic nerve activity and elevated BAT temperature (P<0.05). The i3vt infusion of AGRP (1 nmol) gradually suppressed BAT sympathetic nerve activity and was accompanied by a significant reduction in BAT temperature (P<0.05). In conclusion, the hypothalamic melanocortin system may regulate peripheral energy expenditure, as well as thermogenesis, through its influence on BAT sympathetic nerve activity.
Department of Internal Medicine I, Faculty of Medicine, Oita University, Hasama, Oita 879-5593, Japan.
Tohru
T
Yasuda
Takayuki
T
Masaki
Tetsuya
T
Kakuma
Hironobu
H
Yoshimatsu
D002001:Adipose Tissue, Brown / Q000187:drug effects* / Q000294:innervation; D054369:Agouti-Related Protein; D000818:Animals; D004435:Eating / Q000187:drug effects / Q000502:physiology; D007031:Hypothalamus / Q000502:physiology*; D007276:Injections, Intraventricular; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D011506:Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044105:Receptor, Melanocortin, Type 4 / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D013696:Temperature
C515197:AGRP protein, rat; D054369:Agouti-Related Protein; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D044105:Receptor, Melanocortin, Type 4; D009074:Melanocyte-Stimulating Hormones