Important role of ventromedial hypothalamic carnitine palmitoyltransferase-1a in the control of food intake

Am J Physiol Endocrinol Metab. 2013 Aug 1;305(3):E336-47. doi: 10.1152/ajpendo.00168.2013. Epub 2013 Jun 4.

Abstract

Carnitine palmitoyltransferase-1 (CPT-1) liver isoform, or CPT-1a, is implicated in CNS control of food intake. However, the exact brain nucleus site(s) in mediating this action of CPT-1a has not been identified. In this report, we assess the role of CPT-1a in hypothalamic ventromedial nucleus (VMN). We stereotaxically injected an adenoviral vector containing CPT-1a coding sequence into the VMN of rats to induce overexpression and activation of CPT-1a. The VMN-selective activation of CPT-1a induced an orexigenic effect, suggesting CPT-1a in the VMN is involved in the central control of feeding. Intracerebroventricular administration of etomoxir, a CPT-1 inhibitor, decreases food intake. Importantly, in the animals with VMN overexpression of a CPT-1a mutant that antagonizes the CPT-1 inhibition by etomoxir, the anorectic response to etomoxir was attenuated. This suggests that VMN is involved in mediating the anorectic effect of central inhibition of CPT-1a. In contrast, arcuate nucleus (Arc) overexpression of the mutant did not alter etomoxir-induced inhibition of food intake, suggesting that Arc CPT-1a does not play significant roles in this anorectic action. Furthermore, in the VMN, CPT-1a appears to act downstream of hypothalamic malonyl-CoA action of feeding. Finally, we show that in the VMN CPT-1 activity was altered in concert with fasting and refeeding states, supporting a physiological role of CPT-1a in mediating the control of feeding. All together, CPT-1a in the hypothalamic VMN appears to play an important role in central control of food intake. VMN-selective modulation of CPT-1a activity may therefore be a promising strategy in controlling food intake and maintaining normal body weight.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl Coenzyme A / metabolism
  • Animals
  • Appetite Depressants / pharmacology
  • Arcuate Nucleus of Hypothalamus / metabolism
  • Blotting, Western
  • Body Weight / physiology
  • Carnitine / analogs & derivatives
  • Carnitine / metabolism
  • Carnitine O-Palmitoyltransferase / genetics*
  • Carnitine O-Palmitoyltransferase / physiology*
  • Dependovirus
  • Eating / physiology*
  • Enzyme Activation / drug effects
  • Epoxy Compounds / pharmacology
  • Fasting / physiology
  • Genetic Vectors
  • Hypoglycemic Agents / pharmacology
  • Injections, Intraventricular
  • Male
  • Malonyl Coenzyme A / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Ventromedial Hypothalamic Nucleus / enzymology*
  • Ventromedial Hypothalamic Nucleus / physiology*

Substances

  • Acyl Coenzyme A
  • Appetite Depressants
  • Epoxy Compounds
  • Hypoglycemic Agents
  • acylcarnitine
  • Malonyl Coenzyme A
  • Carnitine O-Palmitoyltransferase
  • carnitine palmitoyltransferase-1a, rat
  • etomoxir
  • Carnitine