Fatty acid synthase inhibitors modulate energy balance via mammalian target of rapamycin complex 1 signaling in the central nervous system.
OBJECTIVE
Evidence links the hypothalamic fatty acid synthase (FAS) pathway to the regulation of food intake and body weight. This includes pharmacological inhibitors that potently reduce feeding and body weight. The mammalian target of rapamycin (mTOR) is an intracellular fuel sensor whose activity in the hypothalamus is also linked to the regulation of energy balance. The purpose of these experiments was to determine whether hypothalamic mTOR complex 1 (mTORC1) signaling is involved in mediating the effects of FAS inhibitors.


METHODS
We measured the hypothalamic phosphorylation of two downstream targets of mTORC1, S6 kinase 1 (S6K1) and S6 ribosomal protein (S6), after administration of the FAS inhibitors C75 and cerulenin in rats. We evaluated food intake in response to FAS inhibitors in rats pretreated with the mTOR inhibitor rapamycin and in mice lacking functional S6K1 (S6K1(-/-)). Food intake and phosphorylation of S6K1 and S6 were also determined after C75 injection in rats maintained on a ketogenic diet.


RESULTS
C75 and cerulenin increased phosphorylation of S6K1 and S6, and their anorexic action was reduced in rapamycin-treated rats and in S6K1(-/-) mice. Consistent with our previous findings, C75 was ineffective at reducing caloric intake in ketotic rats. Under ketosis, C75 was also less efficient at stimulating mTORC1 signaling.


CONCLUSIONS
These findings collectively indicate an important interaction between the FAS and mTORC1 pathways in the central nervous system for regulating energy balance, possibly via modulation of neuronal glucose utilization.
Proulx
Karine
K
Department of Psychiatry, University of Cincinnati, Genome Research Institute, Cincinnati, OH, USA.
Cota
Daniela
D
Woods
Stephen C
SC
Seeley
Randy J
RJ
D000818:Animals; D000855:Anorexia / Q000503:physiopathology; D002490:Central Nervous System / Q000187:drug effects / Q000502:physiology*; D002569:Cerulenin / Q000494:pharmacology; D055423:Diet, Ketogenic; D002149:Energy Intake; D004734:Energy Metabolism / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D064429:Fatty Acid Synthases / Q000037:antagonists & inhibitors*; D055786:Gene Knockout Techniques; D007031:Hypothalamus / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D007930:Leucine / Q000097:blood; D008297:Male; D051379:Mice; D051381:Rats; D020318:Rats, Long-Evans; D019893:Ribosomal Protein S6 Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000502:physiology*
C519510:Crtc1 protein, rat; D004791:Enzyme Inhibitors; D014157:Transcription Factors; D002569:Cerulenin; D064429:Fatty Acid Synthases; D019893:Ribosomal Protein S6 Kinases; C526901:Rps6kb1 protein, rat; D007930:Leucine
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