Li A-J, Wang Q, Smith BR, Ritter S (2012) Lateral and fourth ventricular phloridzin injections stimulate feeding but do not produce hyperglycemia. Neuroscience 2012 Abstracts 93.18. Society for Neuroscience, New Orleans, LA.
Summary: Sodium-coupled glucose transporters (SGLTs) are a family of glucose transporter found in small intestine, kidney, brain capillaries and some neurons. Because SGLTs are membrane receptors, they interact with extracellular glucose in a metabolism-independent manner. Early work using the SGLT inhibitor, phlorizin, suggested that fourth ventricular phlorizin injection increased feeding, but not blood glucose (Flynn FW and Grill HJ, 1985). To further examine this finding, we injected phloridzin, a competitive inhibitor for SGLT-1 and SGLT-2 into the lateral ventricle (LV) or the 4th ventricle (4V) in rats, and the effects of the injections on food intake and blood glucose were examined. We found that both LV and 4V injections of phloridzin enhanced food intake in rats and that LV and 4V injections were of similar potency. In contrast, neither injection elevated blood glucose levels in the present experiments. We also found that enhancement of feeding by 4V phloridzin was abolished by medial hypothalamic injections of anti-dopamine beta hydroxylase saporin, a retrogradely transported catecholamine immunotoxin that selectively lesions norepinephrine and epinephrine neurons that innervate the injection site. Taken together, these results suggest that SGLT receptors in the brain constitute a novel, nonmetabolic, glucose sensing mechanism that contribute to control of food intake.
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