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Cannabinoid CB1 receptors of the parabrachial nucleus in selective modulation of various diets: A comparison with opioids
Journal article   Peer reviewed

Cannabinoid CB1 receptors of the parabrachial nucleus in selective modulation of various diets: A comparison with opioids

N.V. Dipatrizop and K.J. Simansky
Appetite, v 49(1), pp 287-287
01 Jul 2007
DOI: https://doi.org/10.1016/j.appet.2007.03.058

Abstract

Cannabinoid- and opioid-signaling systems have been implicated in many physiological functions, including regulation of feeding and energy balance. In this series of experiments, we compared macronutrient-specific and temporal effects of activating CB1Rs in the parabrachial nucleus (PBN) with mu-opioid receptors (MOPRs) on the intake of standard-chow (SC), high-fat (60%)/high-sucrose diet (HFHS), rationed standard-chow (RSC-baseline intakes raised to near HFHS levels; 30 g given every 24 h=∼100% of daily intake), Crisco ® (fat) and carbohydrate (sucrose). The PBN is a brainstem region associated with integrating neurotransmission from multiple sensory systems, including information regarding ingestion. Separate groups of 6–7 rats were implanted with bilateral cannulae aimed at the lateral PBN and food intake was measured for 4 h. By 30 min post-infusion, the endogenous CB1R agonist 2-arachidonoyl glycerol ([2-AG]; 1.0–2.0 nmol/0.5 μl/side) increased ingestion above baseline of HFHS (from 6.2±0.4 to 10.1±0.8 g), fat (2.6±0.6 to 5.6±1.4) and sucrose (1.9±0.4 to 3.2±0.7). In contrast, 2-AG did not modify eating of SC (0.1±0.1 to 0.1±0.1) and RSC (4.7±0.4 to 4.3±0.7). Thus, hedonically positive sensory properties of the food, rather than the baseline consumption of food, appear to enable CB1R agonists in the PBN to increase eating. In the same animals, the MOPR agonist DAMGO (2 nmol) increased intake of all diets at 4 h (but not 30-min) postinfusion: SC (0.8±0.4 to 3.7±0.9), HFHS (7.7±0.8 to 11.7±1.6), RSC (9.9±1.8 to 11.8±1.6), fat (4.5±0.8 to 6.7±1.2) and sucrose (4.5±0.5 to 5.9±0.3). Parabrachial CB1Rs and MOPRs appear to modulate different temporal components of scheduled meals. Additionally, PBN CB1Rs may interact more selectively than MOPRs with sensory qualities of food. USPHS Grant No. DK067648 to KJS.

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