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Melanocortin receptor agonists in the hypothalamic paraventricular nucleus increase sympathetic nerve activity
Author(s) -
Sharpe Amanda L,
Calderon Alfredo S,
Toney Glenn M
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.853.2
Melanocortins (MCs) act in the CNS to reduce body weight by decreasing food intake and increasing energy expenditure. Whereas injection of MC receptor agonists into the hypothalamic paraventricular nucleus (PVN) increases energy expenditure measured by indirect calorimetry, it is not known if this is mediated by an increase in sympathetic nerve activity (SNA). To investigate this possibility, the MC receptor agonist alpha‐melanocyte stimulating hormone (a‐MSH, 250 pmol in 100 nl/side) was injected bilaterally into the PVN of male Sprague‐Dawley rats and effects on splanchnic SNA, arterial pressure, and heart rate were recorded. a‐MSH caused a steady and prolonged increase in splanchnic SNA (52% increase from baseline at 30 min post injection, P <0.02) together with a small, but significant, increase in mean arterial pressure (11.5±4.5 mmHg, P <0.05). Heart rate was not significantly changed. These results suggest that MCs could increase energy expenditure by increasing SNA via actions in the PVN. Ongoing studies are investigating effects of MC receptor activity in the PVN on lumbar SNA, and the ability of MC receptor blockade in the PVN to attenuate increases in SNA in response to elevated plasma glucose/insulin.