Nitrergic innervation of trigeminal and hypoglossal motoneurons in the cat

• Published in: Brain research 2005-04, Vol.1041 (1), p.29-37
• Main Authors: Pose, Ines, Fung, Simon, Sampogna, Sharon, Chase, Michael H., Morales, Francisco R.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cats; Female; Fundamental and applied biological sciences. Psychology; Hypoglossal Nerve - cytology; Hypoglossal Nerve - enzymology; Male; Medulla; Medulla Oblongata - cytology; Medulla Oblongata - enzymology; Motor control; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Motor Neurons - enzymology; Nerve Tissue Proteins - metabolism; Neural Pathways - cytology; Neural Pathways - enzymology; Neuromodulation; Nitric oxide; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type I; Premotor interneurons; Reticular formation; Reticular Formation - cytology; Reticular Formation - enzymology; Trigeminal Nuclei - cytology; Trigeminal Nuclei - enzymology; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2005.01.092

The present study was undertaken to determine the location of trigeminal and hypoglossal premotor neurons that express neuronal nitric oxide synthase (nNOS) in the cat. Cholera toxin subunit b (CTb) was injected into the trigeminal (mV) or the hypoglossal (mXII) motor nuclei in order to label the corresponding premotor neurons. CTb immunocytochemistry was combined with NADPH-d histochemistry or nNOS immunocytochemistry to identify premotor nitrergic (NADPH-d +/CTb + or nNOS +/ CTb + double-labeled) neurons. Premotor trigeminal as well as premotor hypoglossal neurons were located in the ventro-medial medullary reticular formation in a region corresponding to the nucleus magnocellularis (Mc) and the ventral aspect of the nucleus reticularis gigantocellularis (NRGc). Following the injection of CTb into the mV, this region was found to contain a total of 60 ± 15 double-labeled neurons on the ipsilateral side and 33 ± 14 on the contralateral side. CTb injections into the mXII resulted in 40 ± 17 double-labeled neurons in this region on the ipsilateral side and 16 ± 5 on the contralateral side. Thus, we conclude that premotor trigeminal and premotor hypoglossal nitrergic cells coexist in the same medullary region. They are colocalized with a larger population of nitrergic cells (7200 ± 23). Premotor neurons in other locations did not express nNOS. The present data demonstrate that a population of neurons within the Mc and the NRGc are the source of the nitrergic innervation of trigeminal and hypoglossal motoneurons. Based on the characteristics of nitric oxide actions and its diffusibility, we postulate that these neurons may serve to synchronize the activity of mV and mXII motoneurons.