Endocannabinoids Link Feeding State and Auditory Perception-Related Gene Expression

Abstract

Singing by adult male zebra finches is a learned behavior important for courtship, kin recognition, and nest defense (Zann, 1996) and is inhibited by both brief periods of limited food availability and systemic injection of cannabinoids. These similar effects on singing, combined with increasing evidence for endocannabinoid involvement in feeding behavior, led us to evaluate a possible shared mechanism. We found that limited food availability both reduces singing in a cannabinoid antagonist-reversible manner and increases levels of the endocannabinoid 2-arachidonyl glycerol in various brain regions including the caudal telencephalon, an area that contains auditory telencephalon including the L2 subfield of L (L2) and caudal medial nidopallium (NCM). Development and use of an anti-zebra finch cannabinoid receptor type 1 (CB 1 ) antibody demonstrates distinct, dense cannabinoid receptor expression within song regions including Area X, lMAN (lateral magnocellular nucleus of anterior nidopallium), HVC, RA (robust nucleus of arcopallium), and L2. NCM receives L2 projections and is implicated in integration of auditory information. Activity in this area, determined through expression of the transcription factor ZENK, is increased after exposure to unfamiliar song. Because previous work has shown that these novel songstimulated increases in NCM activity are mitigated by cannabinoid exposure, we tested and found that similar effects on ZENK expression are produced by limiting food. Limited food-related reductions in the activity of NCM neurons were reversed by the cannabinoid antagonist SR141716A (N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide), implicating CB 1 cannabinoid receptor involvement. Taken together, these experiments indicate a link between feeding state and gene expression related to auditory perception that is mediated by endocannabinoid signaling.

The Endocannabinoid 2-Arachidonoyl-Glycerol Controls Odor Sensitivity in Larvae of Xenopus laevis

“…For instance, in the teleost fish Carassius auratus (Valenti et al, 2005), in the zebra finch (Soderstrom et al, 2004) and in rodents (Di Marzo et al, 2001;Kirkham et al, 2002), brain endocannabinoids seem to act as orexigenic mediators. In addition, the CB 1 receptor antagonist AM251 [N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1 H-pyrazole-3-carboxamide] induces suppression of food intake and food-reinforced behavior in rats (McLaughlin et al, 2003).…”

Cannabinoid action in the olfactory epithelium

“…The ECS is also involved in food intake and energy homeostasis (7). For instance, in the teleost fish Carassius auratus (8), in the zebra finch (9), and in rodents (10, 11), brain endocannabinoids seem to act as orexigenic mediators. In addition, AM251 induces suppression of rat food intake and food-reinforced behavior (40).…”

Endogenous cannabinoids in the brain and peripheral tissues: regulation of their levels and control of food intake

“…21 In the songbird, zebra finch, increased 2-AG levels in the brain are observed following food deprivation, and appear to concur at inhibiting neural processes involved in new song learning via the CB 1 ortholog previously cloned in this bird. 22 These data suggest that endocannabinoids in birds and fish, like in mammals, where their levels also increase after short periods of food deprivation (see below), behave as orexigenic mediators. Such a function, at least in mammals, has now been confirmed by strong experimental evidence, and is summarized below.…”