Electrical stimulation of the subfornical organ induces feeding and drinking in satiated rats

Abstract

The subfornical organ (SFO), a circumventricular structure which lacks the normal blood brain barrier has been shown to play a key role in body fluid homeostasis. A role for the SFO in sensing circulating satiety signals has been suggested by electrophysiological studies demonstrating that anorexigenic (leptin and amylin) and orexigenic (ghrelin) satiety signals influence the excitability of separate populations of SFO neurons. The present study examined whether electrical stimulation of the SFO influenced feeding in satiated rats.Male Sprague Dawley rats implanted with concentric bipolar SFO stimulating electrodes received 5 min electrical (100 or 200μA) or sham stimulation and food and water intake measured. Once animals had undergone both electrical and sham stimulation protocols the brain was removed to confirm the location of the stimulating electrode.SFO stimulation (100μA) elicited drinking in 5/6 animals tested (latency to drink: 6.2±2.6 min) but did not elicit eating. Higher stimulation intensities (200μA) elicited eating in all animals tested (food consumption: 0.6 ± 0.12g/100g body weight, n=6) with a mean latency to eat of 8.0 ± 4.0 min and elicited drinking in 5/6 animals (latency to drink: 15.2±2.6 min.) Sham SFO stimulation or stimulation (200μA) in non‐SFO sites (n=6) did not elicit feeding or drinking.The results of the present study showing that SFO stimulation induces feeding in satiated rats, lends support for a role for the SFO as an integrator of circulating peptides that regulate feeding. Supported by Canadian Institutes of Health Research