Brain Regulation of Food Intake following DAMGO Injections

Faculty Advisor

Anaya Mitra



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Brain Regulation of Food Intake following DAMGO Injections

Obesity has become increasingly problematic for developed countries that offer an overwhelming amount of palatable food options for consumers. The present study examined the effects of D-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO), a selective myu-opioid agonist, on the feeding behavior of rats, under both ad libitum and deprived conditions. Central (brain) injections of DAMGO stimulates food intake; specifically palatable food intake. The present study sought to examine whether a rat’s hunger state will influence whether they find standard chow (nutritious but not palatable) more appealing, or a sucrose solution more appealing, following a 24-hour food deprivation session. Rats were surgically fitted with a cannula targeting either the paraventricular nucleus (PVN) or the central nucleus of the amygdala (CeA). The PVN is known to be associated with caloric assessment of food while the CeA is associated with the hedonic assessment of food. After recovery from surgery the rats were given central injections of either DAMGO or physiological saline; 15 minutes after the injection a burette filled with 10% sucrose solution was placed in their cage, together with a jar of powdered chow. Their sucrose and chow intake was monitored for the next 180 minutes. It was predicted that deprived rats would consume more of the standard chow diet, while the non-deprived rats would consume more of the sucrose solution. CeA injections were predicted to result in greater sucrose consumption, while PVN injections were predicted to increase standard chow intake. The results showed sucrose intake was significantly higher following CeA injections of DAMGO (p <0.01); the deprived rats consumed significantly more standard chow than the non-deprived rats (p<.05). However there were no significant interactions between deprivation condition and brain region. These results support previous findings in that the CeA appears to modulate hedonic feeding. Furthermore, under conditions of food deprivation, the preferred food choice switched from the palatable option to the more nutritious option.