cerulenin and Body-Weight

Although metabolites and energy balance have long been known to play roles in the regulation of food intake, the potential role of fatty acid metabolism in this process has been considered only recently. Fatty acid synthase (FAS) catalyzes the condensation of acetyl-CoA and malonyl-CoA to generate long-chain fatty acids in the cytoplasm, while the breakdown of fatty acids (beta-oxidation) occurs in mitochondria and is regulated by carnitine palmitoyltransferase-1 (CPT-1), the rate-limiting step for the entry of fatty acids into the mitochondria. Inhibition of FAS using cerulenin or synthetic FAS inhibitors such as C75 reduces food intake and induces profound reversible weight loss. Subsequent studies reveal that C75 also stimulates CPT-1 and increases beta-oxidation. Hypotheses as to the mechanisms by which C75 and cerulenin mediate their effects have been proposed. Centrally, these compounds alter the expression profiles of feeding-related neuropeptides, often inhibiting the expression of orexigenic peptides. Whether through centrally mediated or peripheral mechanisms, C75 also increases energy consumption, which contributes to weight loss. In vitro and in vivo studies demonstrate that at least part of C75's effects is mediated by modulation of AMP-activated protein kinase (AMPK), a known peripheral energy-sensing kinase. Collectively, these data suggest a role for fatty acid metabolism in the perception and regulation of energy balance.

Topics: 4-Butyrolactone; Animals; Body Weight; Carnitine O-Palmitoyltransferase; Cerulenin; Eating; Energy Metabolism; Fatty Acid Synthases; Fatty Acids; Gene Expression; Humans; Models, Biological; Obesity

Bone and fat cells have an antagonistic relationship. Adipocytes exert a toxic effect on bone cells in vitro through the secretion of fatty acids, which are synthesized by fatty acid synthase (FAS). Inhibition of FAS in vitro rescues osteoblasts from fat-induced toxicity and cell death. In this study, we hypothesized that FAS inhibition would mitigate the loss of bone mass in ovariectomized (OVX) mice. We treated OVX C57BL/6 mice with cerulenin (a known inhibitor of FAS) for 6 weeks and compared their bone phenotype with vehicle-treated controls. Cerulenin-treated mice exhibited a significant decrease in body weight, triglycerides, leptin, and marrow and subcutaneous fat without changes in serum glucose or calciotropic hormones. These effects were associated with attenuation of bone loss and normalization of the bone phenotype in the cerulenin-treated OVX group compared to the vehicle-treated OVX group. Our results demonstrate that inhibition of FAS enhances bone formation, induces uncoupling between osteoblasts and osteoclasts, and favors mineralization, thus providing evidence that inhibition of FAS could constitute a new anabolic therapy for osteoporosis.

Topics: Adiposity; Animals; Biomarkers; Body Weight; Bone Marrow; Bone Remodeling; Bone Resorption; Calcification, Physiologic; Cell Differentiation; Cerulenin; Enzyme Inhibitors; Fatty Acid Synthases; Mice; Mice, Inbred C57BL; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Ovariectomy; Phenotype; RAW 264.7 Cells; Transcription Factors

Fatty liver or hepatic steatosis is a common health problem associated with abnormal liver function and increased susceptibility to ischemia/reperfusion injury. The objective of this study was to investigate the effect of the fatty acid synthase inhibitor cerulenin on hepatic function in steatotic ob/ob mice. Different dosages of cerulenin were administered intraperitoneally to ob/ob mice for 2 to 7 days. Body weight, serum AST/ALT, hepatic energy state, and gene expression patterns in ob/ob mice were examined. We found that cerulenin treatment markedly improved hepatic function in ob/ob mice. Serum AST/ALT levels were significantly decreased and hepatic ATP levels increased in treated obese mice compared to obese controls, accompanied by fat depletion in the hepatocyte. Expression of peroxisome proliferator-activated receptors α and γ and uncoupling protein 2 were suppressed with cerulenin treatment and paralleled changes in AST/ALT levels. Hepatic glutathione content were increased in some cases and apoptotic activity in the steatotic livers was minimally changed with cerulenin treatment. In conclusion, these results demonstrate that fatty acid synthase blockade constitutes a novel therapeutic strategy for altering hepatic steatosis at non-stressed states in obese livers.

Topics: Alanine Transaminase; Animals; Aspartate Aminotransferases; Blotting, Northern; Body Weight; Cerulenin; Chromatography, Gas; Dose-Response Relationship, Drug; Fatty Acid Synthase, Type I; Fatty Liver; Gene Expression Profiling; Immunohistochemistry; Injections, Intraperitoneal; Mice; Mice, Obese; PPAR alpha; PPAR gamma

Brain-specific carnitine palmitoyltransferase-1 (CPT-1c) is implicated in CNS control of food intake. In this article, we explore the role of hypothalamic CPT-1c in leptin's anorexigenic actions. We first show that adenoviral overexpression of CPT-1c in hypothalamic arcuate nucleus of rats increases food intake and concomitantly up-regulates orexigenic neuropeptide Y (NPY) and Bsx (a transcription factor of NPY). Then, we demonstrate that this overexpression antagonizes the anorectic actions induced by central leptin or compound cerulenin (an inhibitor of fatty acid synthase). The overexpression of CPT-1c also blocks leptin-induced down-regulations of NPY and Bsx. Furthermore, the anorectic actions of central leptin or cerulenin are impaired in mice with brain CPT-1c deleted. Both anorectic effects require elevated levels of hypothalamic arcuate nucleus (Arc) malonyl-CoA, a fatty acid-metabolism intermediate that has emerged as a mediator in hypothalamic control of food intake. Thus, these data suggest that CPT-1c is implicated in malonyl-CoA action in leptin's hypothalamic anorectic signaling pathways. Moreover, ceramide metabolism appears to play a role in leptin's central control of feeding. Leptin treatment decreases Arc ceramide levels, with the decrease being important in leptin-induced anorectic actions and down-regulations of NPY and Bsx. Of interest, our data indicate that leptin impacts ceramide metabolism through malonyl-CoA and CPT-1c, and ceramide de novo biosynthesis acts downstream of both malonyl-CoA and CPT-1c in mediating their effects on feeding and expressions of NPY and Bsx. In summary, we provide insights into the important roles of malonyl-CoA, CPT-1c, and ceramide metabolism in leptin's hypothalamic signaling pathways.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Blotting, Western; Body Weight; Brain; Carnitine O-Palmitoyltransferase; Ceramides; Cerulenin; Eating; Humans; Hypothalamus; Leptin; Male; Malonyl Coenzyme A; Mice; Mice, Knockout; Nerve Tissue Proteins; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; Transcription Factors

Cerulenin, a natural fatty acid synthase (FAS) inhibitor, and its synthetic analog C75 are hypothesized to alter the metabolism of neurons in the hypothalamus that regulate ingestive behavior to cause a profound decrease of food intake and an increase in metabolic rate, leading to body weight loss. The bulk of data exclusively originates from mammals (rodents); however, such effects are currently lacking in nonmammalian species. We have, therefore, addressed this issue in broiler chickens because this species is selected for high growth rate and high food intake and is prone to obesity. First, we demonstrate that FAS messenger and protein are expressed in the hypothalamus of chickens. FAS immunoreactivity was detected in a number of brain regions, including the nucleus paraventricularis magnocellularis and the nucleus infundibuli hypothalami, the avian equivalent of the mammalian arcuate nucleus, suggesting that FAS may be involved in the regulation of food intake. Second, we show that hypothalamic FAS gene expression was significantly (P < 0.05) decreased by overnight fasting similar to that in liver, indicating that hypothalamic FAS gene is regulated by energy status in chickens. Finally, to investigate the physiological consequences of in vivo inhibition of fatty acid synthesis on food intake, we administered cerulenin by intravenous injections (15 mg/kg) to 2-wk-old broiler chickens. Cerulenin administration significantly reduced food intake by 23 to 34% (P < 0.05 to P < 0.0001) and downregulated FAS and melanocortin receptors 1, 4, and 5 gene expression (P < 0.05). However, the known orexigenic (neuropeptide Y, agouti gene-related peptide, orexin, and orexin receptor) and anorexigenic (pro-opiomelanocortin and corticotropin-releasing hormone) neuropeptide mRNA levels remained unchanged after cerulenin treatment. These results suggest that the catabolic effect of cerulenin in chickens may be mediated through the melanocortin system rather than the other neuropeptides known to be involved in food intake regulation.

Topics: Animals; Appetite Depressants; Body Weight; Cerulenin; Chickens; Fatty Acid Synthases; Feeding Behavior; Gene Expression Regulation, Enzymologic; Genotype; Hypothalamus; Neuropeptides; Receptors, Melanocortin; RNA, Messenger

To clarify the paradoxic effects of cerulenin, namely its in vitro inhibitory effects on fat catabolism and its in vivo reduction of fat mass, we studied the in vivo and in vitro effects of cerulenin on carnitine palmitoyltransferase-1 (CPT-1) activity, the rate-limiting enzyme of fatty acid oxidation. A single ip injection of cerulenin significantly reduced body weight and increased core temperature without significantly reducing food intake. In situ hybridization study revealed that a single injection of cerulenin did not affect the expression of orexigenic neuropeptide mRNA. Cerulenin's effect on CPT-1 activity was biphasic in the liver and muscle: early suppression during the first 1 h and late stimulation in the 3-5 h after ip treatment. In vitro cerulenin treatment reduced CPT-1 activity, which was overcome by cotreating with catecholamine. Intracerebroventricular injection of cerulenin increased CPT-1 activity significantly in soleus muscle, and this effect was sustained for up to 3 h. Pretreatment with alpha-methyl-p-tyrosine inhibited the cerulenin-induced increase in core temperature and the late-phase stimulating effect of cerulenin on CPT-1 activity. In adrenalectomized mice, cerulenin also increased the activity. In vivo cerulenin treatment enhanced muscle CPT-1 activity in monosodium glutamate-treated arcuate nucleus lesioned mice but not in gold thioglucose-treated ventromedial hypothalamus lesioned mice. These findings suggest that cerulenin-induced late-phase stimulating effects on CPT-1 activity and energy expenditure is mediated by the activation of innervated sympathetic nervous system neurons through the firing of undefined neurons of the ventromedial hypothalamus, rather than the arcuate nucleus.

Topics: Animals; Antifungal Agents; Body Temperature; Body Weight; Carnitine O-Palmitoyltransferase; Cerulenin; Eating; Enzyme Activation; Female; Gene Expression; Hypothalamus; In Vitro Techniques; Male; Mice; Mice, Inbred C57BL; Neuropeptides; Pregnancy; Sympathetic Nervous System

Cerulenin and a related compound, C75, have recently been reported to reduce food intake and body weight independent of leptin through a mechanism hypothesized, like leptin, to involve hypothalamic nutrition-sensitive neurons. To assess whether these inhibitors act through mechanisms similar to mechanisms engaged by leptin, ob/ob and Ay (agouti) mice, as well as fed and fasted wild-type mice, were treated with cerulenin. Like leptin, cerulenin reduced body weight and food intake and increased metabolic rate in ob/ob mice, and cerulenin produced the same effects in wild-type mice, whereas lithium chloride, at doses that produce conditioned taste aversion, reduced metabolic rate. However, in contrast to leptin, cerulenin did not prevent effects of fasting on plasma corticosterone or hypothalamic levels of neuropeptide Y, agouti-related peptide, pro-opiomelanocortin, or cocaine- and amphetamine-related peptide mRNA. Also, in contrast to leptin, cerulenin was highly effective to reduce body weight in Ay mice, in which obesity is caused by blockade of the melanocortin receptor. These data demonstrate that cerulenin produces metabolic effects similar to effects of leptin, but through mechanisms that are independent of, or down-stream from, both leptin and melanocortin receptors.

Topics: Animals; Body Weight; Cerulenin; Drug Resistance; Eating; Endocrine Glands; Fasting; Hypothalamus; Leptin; Male; Melanocyte-Stimulating Hormones; Metabolism; Mice; Mice, Inbred CBA; Mice, Inbred Strains; Neurosecretory Systems; Obesity

Topics: Animals; Antifungal Agents; Body Weight; Cerulenin; Cholecystokinin; DNA; Ethionine; Male; Microscopy, Electron; Organ Size; Pancreas; Pancreatic Juice; Rats; RNA