In vivo fMRI demonstration of hypothalamic function following intraperitoneal glucose administration in a rat model

The hypothalamic functional MRI (fMRI) response in an animal model was studied following energy intake. Six fasted (12 h) Sprague-Dawley (SD) rats were administered an intraperitoneal injection of glucose (0.72 grams/kg body weight), while a mid- sagittal slice through the hypothalamus was continuously imaged for 60 min using a conventional T₂/(*)-weighted gradient-echo sequence. All rats demonstrated a significant acute transient decrease in the fMRI signal intensity (mean: 3.4%) in the hypothalamic region within 12-16 min after intraperitoneal glucose injection. The SD rat may be a suitable model for future fMRI studies of the hypothalamus involving the administration of exogenous nutrients and medications.