Neuroscience 2005 Abstract
| Presentation Number: | 533.15 |
|---|---|
| Abstract Title: | Eating stimulated by intra-PVN infusion of the endocannabinoid 2-AG is reversed by opioid receptor blockade. |
| Authors: |
Kirkham, T. C.*1
; Rogers, E. K.1
; Tucci, S. A.1
1Psychol., Univ. of Liverpool, Liverpool, United Kingdom |
| Primary Theme and Topics |
Homeostatic and Neuroendocrine Systems - Regulation of Food Intake and Body Weight -- Monamines, amino acids, and other regulators |
| Secondary Theme and Topics | Homeostatic and Neuroendocrine Systems<br />- Regulation of Food Intake and Body Weight<br />-- Neuropeptide regulators |
| Session: |
533. Food Intake and Body Weight: Monoamines, Amino Acids, and Other Regulators---Regulatory Mechanisms Poster |
| Presentation Time: | Monday, November 14, 2005 3:00 PM-4:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # KK2 |
| Keywords: | APPETITE, CANNABINOIDS, EATING, FEEDING |
The endocannabinoid system is linked to the processes underlying eating motivation. Stimulation of central CB1 cannabinoid receptors induces feeding, while antagonists, such as rimonabant, suppress food intake. The endocannabinoid 2-arachidonoylglycerol (2-AG) stimulates feeding in rats following injection into the shell region of the nucleus accumbens. Similarly, anandamide stimulates feeding after infusion into the ventromedial nucleus of the hypothalamus. Given the central role of the paraventricular nucleus of the hypothalamus (PVN) in feeding and energy regulation, we determined the ability of 2-AG to stimulate eating when injected into this nucleus.
The hyperphagic actions of the exogenous cannabinoid Δ9-tetrahydrocannabinol (THC) have been shown to be reversed by opioid receptor blockade. Moreover, subanorectic doses of the CB1 antagonist rimonabant and the general opioid receptor antagonist naloxone interact synergistically to suppress food intake. Thus, there is every indication that endogenous cannabinoid and opioid systems interact within brain systems that control appetite. Here we report the consequences of naloxone treatment on 2-AG induced eating.
Male Lister hooded rats were stereotaxically implanted with unilateral cannulae aimed at the PVN. The effects of intra-PVN 2-AG were examined alone, or after pre-treatment with sub-anorectic doses of naloxone. One hour intake tests were conducted in non-deprived rats tested during the light phase. 2-AG significantly increase food (chow) intake at a dose of 2.0ng. This effect was abolished by systemic naloxone pre-treatment at either 0.1 or 1.0 mg/kg.
This is the first demonstration of endocannabinoid-induced hyperphagia in the PVN, and of its mediation by opioid systems. These findings further support the importance of endocannabinoids in the central regulation of appetite. The sensitivity of 2-AG feeding to opioid receptor blockade confirms the functional relationship between endocannabinoid and opioid systems in the mediation of appetite.
The hyperphagic actions of the exogenous cannabinoid Δ9-tetrahydrocannabinol (THC) have been shown to be reversed by opioid receptor blockade. Moreover, subanorectic doses of the CB1 antagonist rimonabant and the general opioid receptor antagonist naloxone interact synergistically to suppress food intake. Thus, there is every indication that endogenous cannabinoid and opioid systems interact within brain systems that control appetite. Here we report the consequences of naloxone treatment on 2-AG induced eating.
Male Lister hooded rats were stereotaxically implanted with unilateral cannulae aimed at the PVN. The effects of intra-PVN 2-AG were examined alone, or after pre-treatment with sub-anorectic doses of naloxone. One hour intake tests were conducted in non-deprived rats tested during the light phase. 2-AG significantly increase food (chow) intake at a dose of 2.0ng. This effect was abolished by systemic naloxone pre-treatment at either 0.1 or 1.0 mg/kg.
This is the first demonstration of endocannabinoid-induced hyperphagia in the PVN, and of its mediation by opioid systems. These findings further support the importance of endocannabinoids in the central regulation of appetite. The sensitivity of 2-AG feeding to opioid receptor blockade confirms the functional relationship between endocannabinoid and opioid systems in the mediation of appetite.
Supported by BBSRC
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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