ABSTRACT
BACKGROUND: Transient hyperthermic shifts in body temperature have been linked to the endogenous hormone calcitonin gene-related peptide (CGRP), which can increase sympathetic activation and metabolic heat production. Recent studies have demonstrated that these centrally mediated responses may result from CGRP dependent changes in the activity of thermoregulatory neurons in the preoptic and anterior regions of the hypothalamus (POAH). RESULTS: Using a tissue slice preparation, we recorded the single-unit activity of POAH neurons from the adult male rat, in response to temperature and CGRP (10 muM). Based on the slope of firing rate as a function of temperature, neurons were classified as either warm sensitive or temperature insensitive. All warm sensitive neurons responded to CGRP with a significant decrease in firing rate. While CGRP did not alter the firing rates of some temperature insensitive neurons, responsive neurons showed an increase in firing rate. CONCLUSION: With respect to current models of thermoregulatory control, these CGRP dependent changes in firing rate would result in hyperthermia. This suggests that both warm sensitive and temperature insensitive neurons in the POAH may play a role in producing this hyperthermic shift in temperature.
Subject(s)
Anterior Hypothalamic Nucleus/drug effects , Calcitonin Gene-Related Peptide/pharmacology , Hypothalamus, Anterior/drug effects , Neurons/drug effects , Action Potentials/drug effects , Action Potentials/physiology , Animals , Anterior Hypothalamic Nucleus/cytology , Anterior Hypothalamic Nucleus/physiology , Body Temperature Regulation/drug effects , Electrophysiology/instrumentation , Electrophysiology/methods , Hypothalamus, Anterior/cytology , Hypothalamus, Anterior/physiology , Male , Microelectrodes , Neural Pathways/drug effects , Neural Pathways/physiology , Neurons/cytology , Neurons/physiology , Preoptic Area/cytology , Preoptic Area/drug effects , Preoptic Area/physiology , Rats , Rats, Sprague-Dawley , Regression Analysis , Temperature , Tissue Culture TechniquesABSTRACT
Understanding why we eat and the motivational factors driving food choices is important for addressing the epidemics of obesity, diabetes, and cardiovascular disease. Eating behavior is a complex interplay of physiological, psychological, social, and genetic factors that influence meal timing, quantity of food intake, and food preference. Reviewed here is the current and emerging knowledge of the genetic influences on eating behavior and how these relate to obesity; particular emphasis is placed on the genetics of taste, meal size, and selection, and the emerging use of functional magnetic resonance imaging to study neural reactions in response to food stimuli in normal, overweight, and obese individuals.