Persistence of sham feeding after intragastric meals in rats

Endocannabinoid Receptor Antagonists

Obesity has been described as a global epidemic. Its increasing prevalence is matched by growing costs, not only to the health of the individual, but also to the medical services required to treat a range of obesity-related diseases. In most instances, obesity is a product of progressively less energetic lifestyles and the over-consumption of readily available, palatable, and highly caloric foods. Past decades have seen massive investment in the search for effective anti-obesity therapies, so far with limited success. An important part of the process of developing new pharmacologic treatments for obesity lies in improving our understanding of the psychologic and physiologic processes that govern appetite and bodyweight regulation. Recent discoveries concerning the endogenous cannabinoids are beginning to give greater insight into these processes. Current research indicates that endocannabinoids may be key to the appetitive and consummatory aspects of eating motivation, possibly mediating the craving for and enjoyment of the most desired, most fattening foods. Additionally, endocannabinoids appear to modulate central and peripheral processes associated with fat and glucose metabolism. Selective cannabinoid receptor antagonists have been shown to suppress the motivation to eat, and preferentially reduce the consumption of palatable, energy-dense foods. Additionally, these agents act to reduce adiposity through metabolic mechanisms that are independent of changes in food intake. Given the current state of evidence, we conclude that the endocannabinoids represent an exciting target for new anti-obesity therapies.

Persistence of sham feeding after real-fed gastric loads in rats

Esophagostomized rats were permitted to "real-feed" a glucose solution (Experiment 1) or milk (Experiment 2), by receiving intragastric (IG) infusions concurrent with sham feeding. This was done for the first part of the feeding session; then the IG infusions were discontinued so that subsequent ingestion was sham. When such infusions stopped after 80% of real-meal volume had been delivered, they had no measurable effect on subsequent oral ingestion: sham feeding persisted as if nothing had been delivered IG. Therefore, the onset of postingestive satiety, at least in experienced sham-feeding rats, is all-or-none or close to it: if the IG loads are even slightly short of what is required to abolish sham feeding, then they do not affect sham feeding at all. This is so even if the postingestive events occur within their normal behavioral context.