Importance of melanin-concentrating hormone receptor for the acute effects of ghrelin.
The hypothalamic peptide melanin-concentrating hormone (MCH) and the gastric hormone ghrelin take part in the regulation of energy homeostasis and stimulate food intake. In the present study, ghrelin was administered centrally to MCH-receptor knockout (MCHr KO) mice. MCHr KO mice and wild type (WT) controls both consumed more food when treated with ghrelin. After ghrelin administration, the serum levels of insulin increased only in WT mice whereas the serum levels of corticosterone increased both in WT and MCHr KO mice. The level of growth hormone (GH) mRNA in the pituitary gland was markedly increased in response to ghrelin injection in the WT mice but was unaffected in the MCHr KO mice. The different ghrelin responses could not be explained by a difference in growth hormone secretagogue receptor expression between MCHr KO and WT mice in the pituitary or hypothalamus. In summary, the MCHr is not required for ghrelin induced feeding. However, the MCHr does play a role for the effect of ghrelin on GH expression in the pituitary and serum insulin levels.
Bjursell
Mikael
M
Department of Physiology and Pharmacology, Gothenburg University, Sweden. mikael.bjursell@astrazeneca.com
Egecioglu
Emil
E
Gerdin
Anna-Karin
AK
Svensson
Lennart
L
Oscarsson
Jan
J
Morgan
David
D
Snaith
Michael
M
Törnell
Jan
J
Bohlooly-Y
Mohammad
M
D000818:Animals; D003345:Corticosterone / Q000097:blood*; D004435:Eating / Q000187:drug effects* / Q000502:physiology*; D054439:Ghrelin; D013006:Growth Hormone / Q000378:metabolism; D007328:Insulin / Q000097:blood*; D051379:Mice; D018345:Mice, Knockout; D036361:Peptide Hormones / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D011979:Receptors, Pituitary Hormone / Q000172:deficiency / Q000378:metabolism*
D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D011979:Receptors, Pituitary Hormone; C092274:melanin-concentrating hormone receptor; D013006:Growth Hormone; D003345:Corticosterone