Insulin modulates the electrical activity of dissociated and cultured Subfornical Organ (SFO) neurons in male Sprague Dawley Rats

Abstract

The brain is protected by the blood brain barrier (BBB); areas lacking the BBB are termed circumventricular organs (CVOs). The SFO, a CVO is capable of detecting and responding to satiety signals that regulate energy balance. Insulin, a satiety signal, plays a role in energy balance and its actions at the SFO are unknown. The goal was to determine if cultured SFO neurons are electrophysiologically sensitive to insulin. Of 27 neurons tested 33% neurons hyperpolarized (-8.7 ± 1.7 mV), 37% neurons depolarized (10.5 ±2.8 mV) and 30% neurons (8 out of 27) showed no change in membrane potential. Input resistance changes indicated the modulation of two ion channels. Pharmacological data suggests hyperpolarization arises from the opening of KATP channels and depolarization results from the opening of non-selective cationic channels. Thus insulin modulates the electrical activity of SFO neurons and supports that the SFO is a sensor for maintaining energy homeostasis.