Article

Comparison of basal neuropeptide Y and corticotropin releasing factor levels between the high ethanol drinking C57BL/6J and low ethanol drinking DBA/2J inbred mouse strains

Department of Psychology, University of North Carolina, Chapel Hill, North Carolina 27599-3270, USA.
Alcoholism Clinical and Experimental Research (Impact Factor: 3.31). 06/2005; 29(5):721-9. DOI: 10.1097/01.ALC.0000164375.16838.F3
Source: PubMed

ABSTRACT Recent genetic and pharmacological evidence indicates that low neuropeptide Y (NPY) levels in brain regions involved with neurobiological responses to ethanol promote increased ethanol consumption. Because of their opposing actions, it has been suggested that NPY and corticotropin releasing factor (CRF) exert a reciprocal regulation on drug self-administration. It has been widely reported that inbred C57BL/6 mice consume significantly higher amounts of ethanol than do DBA/2 mice. Therefore, we used immunohistochemical techniques to determine if basal NPY and/or CRF levels differed in predicted directions between C57BL/6J and DBA/2J mice.
Ethanol-naive C57BL/6J and DBA/2J mice were deeply anesthetized with sodium pentobarbital (100 mg/kg) and perfused transcardially with 0.1 mM of phosphate-buffered saline followed by 4% paraformaldehyde in buffered saline. Brains were collected and postfixed for 4 hr at 4 degrees C and then were cut into 35-microm sections. Tissues containing the nucleus accumbens (NAc), hypothalamus, and amygdala were processed for NPY or CRF immunoreactivity using immunofluorescent or DAB techniques. Immunoreactivity was quantified from digital images using Image J software.
The C57BL/6J mice showed reduced NPY expression in the NAc shell, the basolateral amygdala, and the central nucleus of the amygdala when compared with DBA/2J mice. However, these strains did not differ in CRF expression in any of the brain regions analyzed.
These data suggest that low NPY levels in the amygdala and/or the shell of the NAc, which are not compensated for by similar changes in CRF levels, may contribute to the high ethanol consumption characteristic of C57BL/6J mice.

Download full-text

Full-text

Available from: Todd E Thiele, Jul 28, 2015
0 Followers
  • Source
    • "Digital images of immunofluorescence were obtained using the Progress Pro 2.7.6 software under 20 × magnification. For all regions of interest, immunoreactive cell bodies or processes were quantified using Image J software (Image J, National Institutes of Health) and the method described by Hayes and colleagues (Hayes et al., 2005). Percentages of optical densities (Mean Grey Values: estimates of the staining intensity ) from a selected brain region relative to a subthreshold background were obtained. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Abnormal function of the neuroendocrine stress system has been implicated in the behavioral impairments observed following brain ischemia. The current study examined long-term changes in stress signals regulation 30 days following global cerebral ischemia. Experiment 1 investigated changes in the expression of corticotropin releasing hormone (CRH) and its subtype 1 receptor (CRHR1), glucocorticoid receptors (GR) in the paraventricular nucleus of the hypothalamus (PVN), the central nucleus of the amygdala (CeA), and the CA1 subfield of the hippocampus. Tyrosine hydroxylase (TH) was determined at the locus coeruleus (LC). Experiment 2 investigated the role of central CRHR1 activation on corticosterone (CORT) secretion at multiple time intervals following global ischemia after exposure to an acute stressor. Findings from Experiment 1 demonstrated a persistent increase in GR, CRH and CRHR1 immunoreactivity (ir) at the PVN, reduced GR and CRHR1 expression in pyramidal CA1 neurons, and increased LC TH expression in ischemic rats displaying working memory errors in the radial arm Maze. Findings from Experiment 2 revealed increased CORT secretion up to 7 days, but no longer present 14 and 21 days post ischemia. However upon an acute restraint stress induced 27 days following reperfusion, ischemic rats had increased plasma CORT secretions compared to sham-operated animals, suggesting HPA axis hypersensitivity. Antalarmin (2μg/2μl) pretreatment significantly attenuated post ischemic elevation of basal and stress-induced CORT secretion. These findings support persistent neuroendocrine dysfunctions following brain ischemia likely to contribute to emotional and cognitive impairments observed in survivors of cardiac arrest and stroke.
    Hormones and Behavior 01/2014; 65(3). DOI:10.1016/j.yhbeh.2014.01.003 · 4.51 Impact Factor
  • Source
    • "The literature surrounding NPY expression in alcohol-preferring animals is mixed and largely depends on the line of rats used, as well as the availability of ethanol. With ethanol available, NPY immunoreactivity in various hypothalamic regions has been shown to be increased in alcohol-preferring P rats compared control NP rats (Hwang et al. 1999), while reduced in these regions in high-alcohol drinking HAD compared to LAD rats (Hwang et al. 1999) and in mesolimbic regions of the ethanol-preferring C57BL/6J mice (Hayes et al. 2005). In contrast, no changes in mRNA expression of NPY have been noted in any of these brain regions of alcohol-preferring animals at baseline (Caberlotto et al. 2001; Kinoshita et al. 2004). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Consummatory behavior is driven by both caloric and emotional need, and a wide variety of animal models have been useful in research on the systems that drive consumption of food and drugs. Models have included selective breeding for a specific trait, manipulation of gene expression, forced or voluntary exposure to a substance, and identification of biomarkers that predict which animals are prone to overconsuming specific substances. This research has elucidated numerous brain areas and neurochemicals that drive consummatory behavior. Although energy homeostasis is primarily mediated by the hypothalamus, reinforcement is more strongly mediated by nuclei outside the hypothalamus, in mesocorticolimbic regions. Orexigenic neurochemicals that control food intake can provide a general signal for promoting caloric intake or a more specific signal for stimulating consumption of a particular macronutrient, fat, carbohydrate, or protein. The neurochemicals involved in controlling fat ingestion--galanin, enkephalin, orexin, melanin-concentrating hormone, and the endocannabinoids--show positive feedback with this macronutrient, as these peptides both increase fat intake and are further stimulated by its intake. This positive association offers some explanation for why foods high in fat are so often overconsumed. Consumption of ethanol, a drug of abuse that also contains calories, is similarly driven by the neurochemical systems involved in fat intake, according to evidence that closely relates fat and ethanol consumption. Further understanding of the systems involved in consummatory behavior will enable the development of effective therapies for the treatment of both overeating and drug abuse.
    ILAR journal / National Research Council, Institute of Laboratory Animal Resources 03/2012; 53(1):35-58. DOI:10.1093/ilar.53.1.35 · 1.05 Impact Factor
  • Source
    • "Brains were cut using a vibrotome into 40 μm sections and were then stored in PBS. IHC procedures were based on those routinely used in our laboratory (Hayes et al., 2005; Thiele et al., 1996, 1997, 1998a,b, 2000). Sections were evenly divided into 2 sets (every-other section) for processing with α-MSH or AgRP antibodies. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The melanocortin (MC) system is composed of peptides that are cleaved from the polypeptide precursor, pro-opiomelanocortin (POMC). Previous research has shown that MC receptor (MCR) agonists reduce, and MCR antagonists increase, ethanol consumption in rats and mice. Consistently, genetic deletion of the endogenous MCR antagonist, agouti-related protein (AgRP), causes reductions of ethanol-reinforced lever pressing and binge-like ethanol drinking in C57BL/6J mice. Ethanol also has direct effects on the central MC system, as chronic exposure to an ethanol-containing diet causes significant reductions of alpha-melanocyte stimulating hormone (alpha-MSH) immunoreactivity in specific brain regions of Sprague-Dawley rats. Together, these observations suggest that the central MC system modulates neurobiological responses to ethanol. To further characterize the role of the MC system in responses to ethanol, here we compared AgRP and alpha-MSH immunoreactivity in response to an acute injection of saline or ethanol between high ethanol drinking C57BL/6J mice and moderate ethanol drinking 129/SvJ mice. Mice received an intraperitoneal (i.p.) injection of ethanol (1.5 g/kg or 3.5 g/kg; mixed in 0.9% saline) or an equivolume of 0.9% saline. Two hours after injection, animals were sacrificed and their brains were processed for AgRP and alpha-MSH immunoreactivity. Results indicated that acute ethanol administration triggered a dose-dependent increase in AgRP immunoreactivity in the arcuate (ARC) of C57BL/6J mice, an effect that was not evident in the 129/SvJ strain. Although acute administration of ethanol did not influence alpha-MSH immunoreactivity, C57BL/6J mice had significantly greater overall alpha-MSH immunoreactivity in the ARC, dorsomedial, and lateral regions of the hypothalamus relative to the 129/SvJ strain. In contrast, C57BL/6J mice displayed significantly lower alpha-MSH immunoreactivity in the medial amygdala. The results show that acute ethanol exposure has direct effects on endogenous AgRP activity in ethanol preferring C57BL/6J mice. It is suggested that ethanol-induced increases in AgRP may be part of a positive feedback system that stimulates excessive binge-like ethanol drinking in C57BL/6J mice. Inherent differences in alpha-MSH immunoreactivity may contribute to differences in neurobiological responses to ethanol that are characteristically observed between the C57BL/6J and 129/SvJ inbred strains of mice.
    Alcoholism Clinical and Experimental Research 04/2010; 34(4):693-701. DOI:10.1111/j.1530-0277.2009.01138.x · 3.31 Impact Factor
Show more