The Role of Neuropeptide Y in Fat Deposition in Birds

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Neuropeptide Y is a neurotransmitter, but also functions as a hormone to affect other organs such as adipose tissue. It is one of the strongest stimuli of food intake in birds and mammals, and promotes fat storage in mammals. There is no information on the role of NPY in fat deposition in birds and mechanisms governing adipose accumulation in avian species are still unclear. Increased seasonal food intake and fat accumulation in birds and mammals (e.g., in preparation for migration and hibernation, respectively) are important for survival. Thus, a greater understanding of adipose development should provide novel insight into evolutionary adaptations for seasonal changes in body composition. Based on preliminary data from lean and fat birds showing differences in NPY and receptor gene expression in adipose tissue and differential food intake responses to NPY, it is hypothesized that NPY will affect fat formation and maintenance in birds and that these processes will be affected by both exogenous and adipose-derived NPY. A greater understanding of the physiological processes associated with fat deposition in birds has broad applications to all classes of vertebrates that undergo periodic acclimation to food shortage by adjusting appetite and energy storage in fat. The findings may also contribute to obesity research and potentially reduce healthcare costs.This work has four main goals, using chickens as the model organism: 1) Characterize the avian adipose-hypothalamic NPY axis by quantifying the abundance of NPY and its receptors in adipose tissue and hypothalamus. 2) Understand the function of NPY in regulating development of fat cells. Approaches include evaluating effects of NPY treatment on pre-adipocyte proliferation and differentiation in an in-vitro fat culture system. 3) Determine if adipose-derived NPY plays a role in adipogenesis. NPY mRNA will be knocked-down in pre-adipocytes and effects on differentiation will be evaluated. 4) Elucidate the signaling pathway(s) responsible for NPY's effects on fat cells. Fat cells will be treated with NPY receptor sub-type-specific antagonists to demonstrate the mechanism through which NPY affects fat.