Effect of Orexin-A on Glucose Sensitive Neurons in the Hypothalamus of Rats

Orexin-A is an excitatory neuropeptide that mainly located in the lateral hypothalamus(LHA). Orexin-A can regulates multiple physiological activity that include arousal, wakefulness and appetite. We aim to discuss the effects of orexin-A on the glucose sensitive neurons in the hypothalamus, in order to make further investigation of potential mechanisms in the appetite system. Cerebral stereotaxic technique was used to inject orexin-A and glucose into nucleus accumbens of rats. Extracellular single unit discharges were used to observe the activity of glucose sensitive neurons in the nucleus accumbens of rats. Sixty-eight glucose sensitive neurons were recorded after microinjection of glucose into nucleus accumbens. Based on different sensitive reactivity, the discharge frequency of forty-two neurons were increased (defined as glucose excitatory neuron) and twenty neurons were decreased (defined as glucose inhibitory neuron). The discharge frequency of thirty neurons were increased in the glucose excitatory neurons after administration of orexin-A through four-barrel glass microelectrode. The discharge frequency of fifteen neurons were increased in the glucose inhibitory neurons after administration of orexin-A through four-barrel glass microelectrode. The effect of orexin-A on turning the discharge frequency of glucose sensitive neurons was abolished by orexin-A receptor antagonists SB-334867. The change of discharge frequency of glucose sensitive neurons did not have significant difference after injection of saline through three-barrel glass microelectrode. It is suggested that orexin-A can regulate glucose sensitive neurons in nucleus accumbens, which may be parts of mechanism of the regulation of food intake.