Nitric oxide production by brain stem neurons is required for normal performance of eye movements in alert animals.
Although nitric oxide (NO) is produced by discrete groups of neurons in the brain, participation of NO in premotor structures directly involved in reflexively evoked, sensory-motor functions has not been demonstrated so far. We now show that NO is a physiological mediator in the generation of a specific motor response in alert behaving animals. In the oculomotor system, numerous neurons expressing nitric oxide synthase (NOS) are located in the prepositus hypoglossi, a nucleus involved in the control of horizontal eye movements. Unilateral inhibition of NOS within this nucleus results in severe ocular nystagmus with slow phases directed to the contralateral side. Accordingly, local increases of NO or cyclic GMP produced a nystagmus in the opposite direction. It is concluded that a balanced production of NO by prepositus hypoglossi neurons is a necessary condition for the normal performance of eye movements in alert animals.
Departamento de Fisiología y Biología Animal, Facultad de Biología, Universidad de Sevilla, Spain.
B
B
Moreno-López
M
M
Escudero
J M
JM
Delgado-Garcia
C
C
Estrada
D000818:Animals; D001931:Brain Mapping; D001933:Brain Stem / Q000502:physiology*; D002415:Cats; D006152:Cyclic GMP / Q000378:metabolism; D004558:Electric Stimulation; D005133:Eye Movements / Q000187:drug effects / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009474:Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009760:Nystagmus, Physiologic / Q000187:drug effects; D009801:Oculomotor Muscles / Q000294:innervation*
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester