OXYTOCIN INNERVATION OF SPINAL PREGANGLIONIC NEURONS PROJECTING TO THE SUPERIOR CERVICAL-GANGLION IN THE RAT

The paraventricular nucleus of the hypothalamus is a major integrative nucleus for relaying information from the suprachiasmatic nucleus to the autonomic system. The precise pathway by which this information ca n influence autonomic functions, such as melatonin synthesis in the pi neal gland, is not clear. In the present study, we used a retrograde t racer injected in the superior cervical ganglion to identify spinal pr eganglionic neurons. One of the main neurotransmitters present in desc ending projections of the paraventricular nucleus of the hypothalamus, oxytocin, was detected with immunocytochemistry to visualise possible contacts with the neurons located in the intermediolateral column of the spinal cord and projecting to the superior cervical ganglion. Alth ough many appositions could be seen at the light-microscopic level, th is abundance could not be confirmed at the electron-microscopic level. The implications of these observations for the overall timing message received by the spinal preganglionic neurons are discussed.