It Takes Two to Tango: Investigating the Relationship between Ghrelin and Endocannabinoids within the Ventral Tegmental Area with Regards to Feeding

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Creator: 

Edwards, Alexander

Date: 

2014

Abstract: 

Ghrelin is a hormone that targets the brain to increase food intake and energy balance.
Recent evidence suggests that ghrelin increases appetite in part by acting on growth hormone
secretagogue receptors (GHSR) in the ventral tegmental area (VTA), a brain region associated
with reward seeking behaviors. The ability of ghrelin to induce appetite is reminiscent of the
appetite inducing effects of endogenous cannabinoids (CBs). Interestingly, ghrelin’s ability to
stimulate feeding within the hypothalamus is dependent on a functional CB system within this
region. In the present thesis we
hypothesized that ghrelin and CB systems work in tandem
within the VTA to stimulate feeding. Here we showed that ghrelin significantly increased food
intake (p < .05) when directly microinjected into the VTA of rats. Furthermore, we
demonstrated that this corresponding increase in food intake depended on a functional
endocannabinoid system as peripheral pre-treatment with a selective CB-1 receptor (CB-1R)
antagonist (i.e. rimonabant) completely attenuated this increase in food intake to control rat
levels. Furthermore, we also demonstrated via reverse transcription quantitative
polymerase
chain reaction (RT-qPCR) experiments that CB-1R mRNA expression is significantly lower in the
VTA but enhanced in the prefrontal cortex (PFC) of GHSR knock-out (GHSR KO) relative to wildtype
(WT) rats (p < .05). Together, these data provide evidence that ghrelin targets the VTA to
increase food intake through a mechanism that requires a functional endocannabinoid system.

Subject: 

Neuroscience
Biology - Molecular
Behavioral

Language: 

English

Publisher: 

Carleton University

Thesis Degree Name: 

Master of Science: 
M.Sc.

Thesis Degree Level: 

Master's

Thesis Degree Discipline: 

Neuroscience

Parent Collection: 

Theses and Dissertations

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