Autonomic neurons and paraneurons (SIF cells) in the sympathetic ganglia regulating guinea pig proximal colon: immunohistochemical studies.
Additional evidence for the existence of subclasses of SIF cells is described. Type II SIF cells in the inferior mesenteric ganglia contain enkephalin, vasoactive intestinal polypeptide (VIP), somatostatine (SOM), neuropeptide tyrosine (NPY), or dynorphin (DYN) in variable combinations in addition to noradrenalin. These transmitters or modulators can affect the autoreceptors of the SIF cell themselves or modify the synatpic transmission and the activity of sympathetic ganglionic neurons through portal blood vessels. Tyrosine hydroxylase/NPY immunoreactive nerve terminals from sympathetic ganglia innervate blood vessels and both submucous and myenteric ganglia. DYN/VIP/cholecystokinin neurons in the nerve plexus send axon collaterals to the inferior mesenteric ganglia and form a feedback loop. Substance P (SP) and calcitonin gene related peptide may exist in sensory nerve terminals. SP neurons in the myenteric ganglia innervate smooth muscles. SOM neurons inhibitory interneurons in the ganglia. SIF cells act as secretory paraneurons, the effect being long-lasting and nonspecific, while sympathetic neurons innervate both nerve plexus and intestinal tissues, and the effects in this case are specific, fast and of short duration.
Chiba
T
T
Department of Anatomy, Chiba University School of Medicine, Japan.
Masuko
S
S
D000818:Animals; D001341:Autonomic Nervous System / Q000166:cytology* / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism; D003106:Colon / Q000294:innervation*; D004702:Endocrine Glands / Q000166:cytology* / Q000378:metabolism; D005453:Fluorescence; D005728:Ganglia, Sympathetic / Q000166:cytology* / Q000502:physiology; D006168:Guinea Pigs; D007150:Immunohistochemistry; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009475:Neurons, Afferent / Q000166:cytology* / Q000378:metabolism
D002395:Catecholamines