Evidence that oxytocin is an endogenous stimulator of autonomic sympathetic preganglionics: the pupillary dilatation response to vaginocervical stimulation in the rat.
Vaginocervical mechanostimulation (VS) was shown previously to release oxytocin within the spinal cord and to induce pupillary dilatation. In the present study, (a) injection of oxytocin directly to the spinal cord (10 or 25 microg intrathecally [i.t.] in 5 microl saline) induced pupillary dilatation when observed 1 min after the end of the injection and (b) injection of an oxytocin receptor antagonist ([d(CH2)5-Tyr (Me)2-Orn8]-Vasotocin [OTA]; 25 microg i.t. in 5 microl saline) significantly attenuated the pupillary dilatation response to VS, when VS was applied 3 min after the end of the injection. Since activation of autonomic sympathetic preganglionic neurons in the thoracic spinal cord produces pupillary dilatation, we propose that oxytocin is a central nervous system neurotransmitter that stimulates these neurons directly, or perhaps indirectly, and thus is a mediator of VS-produced pupillary dilatation.
Sansone
G R
GR
Department of Psychology, Rutgers, The State University of New Jersey, Newark, NJ 07102, USA.
Komisaruk
B R
BR
D000818:Animals; D002584:Cervix Uteri / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D008465:Mechanoreceptors / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism* / Q000494:pharmacology; D010121:Oxytocin / Q000378:metabolism* / Q000494:pharmacology; D010812:Physical Stimulation; D011680:Pupil / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors / Q000378:metabolism; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014621:Vagina / Q000187:drug effects / Q000294:innervation / Q000502:physiology
D018377:Neurotransmitter Agents; D018045:Receptors, Oxytocin; D010121:Oxytocin