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Anatomical and pharmacological relationship between acetylcholine and nitric oxide in the prepositus hypoglossi nucleus of the cat: Functional implications for eye‐movement control
Author(s) -
MárquezRuiz Javier,
Morcuende Sara,
NavarroLópez Juan De Dios,
Escudero Miguel
Publication year - 2007
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21397
Subject(s) - acetylcholine , nucleus , cholinergic , neuroscience , tonic (physiology) , choline acetyltransferase , biology , cholinergic neuron , medial vestibular nucleus , nitric oxide , endocrinology , vestibular nuclei , central nervous system
The prepositus hypoglossi (PH) nucleus has been proposed as a pivotal structure for horizontal eye‐position generation in the oculomotor system. Recent studies have revealed that acetylcholine (ACh) in the PH nucleus could mediate the persistent activity necessary for this process, although the origin of this ACh remains unknown. It is also known that nitric oxide (NO) in the PH nucleus plays an important role in the control of velocity balance, being involved in a negative feedback control of tonic signals arriving at the PH nucleus. As it could be expected that neurons taking part in eye‐position generation must control their tonic background inputs, the existence of a relationship between nitrergic and cholinergic neurons is hypothesized. In the present study we analyzed the distribution, size, and morphology of choline acetyltransferase‐positive neurons, and their relationship with neuronal nitric oxide synthase in the PH nucleus of the cat. As presumed, some 96% of cholinergic neurons were also nitrergic in the PH nucleus, suggesting that NO is regulating the level of ACh released by cholinergic PH neurons. Furthermore, we studied the alterations induced by muscarinic‐receptor agonists and antagonists on spontaneous and vestibularly induced eye movements in the alert cat and compared them with those induced in previous studies by modification of NO levels in the same animal preparation. The results suggest that ACh is necessary for the generation of saccadic and vestibular eye‐position signals, whereas the NO is stabilizing the eye‐position generator by controlling background activity reaching cholinergic neurons in the PH nucleus. J. Comp. Neurol. 503:407–420, 2007. © 2007 Wiley‐Liss, Inc.