P2X 5 receptors are expressed on neurons containing arginine vasopressin and nitric oxide synthase in the rat hypothalamus

Abstract

In this study, the P2X 5 receptor was found to be distributed widely in the rat hypothalamus using single and double labeling immunofluorescence and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. The regions of the hypothalamus with the highest expression of P2X 5 receptors in neurons are the paraventricular and supraoptic nuclei. The intensity of P2X 5 immunofluorescence in neurons of the ventromedial nucleus was low. 70–90% of the neurons in the paraventricular nucleus and 46–58% of neurons in the supraoptic and accessory neurosecretory nuclei show colocalization of P2X 5 receptors and arginine vasopressin (AVP). None of the neurons expressing P2X 5 receptors shows colocalization with AVP in the suprachiasmatic and ventromedial nuclei. 87–90% of the neurons in the lateral and ventral paraventricular nucleus and 42–56% of the neurons in the accessory neurosecretory, supraoptic and ventromedial nuclei show colocalization of P2X 5 receptors with neuronal nitric oxide synthase (nNOS). None of the neurons expressing P2X 5 receptors in the suprachiasmatic nucleus shows colocalization with nNOS. These findings provide a morphological basis for possible functional interactions between the purinergic and nitrergic or vasopressinergic neurotransmitter systems.