An immunohistochemical study of neuropeptides and neuron‐specific proteins present in the small intestine of the black‐capped capuchin (Cebus appela)

Abstract

Abstract Antisera against neuron specific enolase (NSE), calbindin and the neuropeptides substance P (SP), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), enkephalin (ENK) and somntostatin (SOM) were used to demonstrate the presence of nerve fibres and cell bodies in the small intestine of the black‐capped capuchin, Cebus appela. NSE‐immunoreactive (IR) nerve fibres werefoundin all layers of the intestinal wall, except the longitudinal muscle, and immuno‐reactive nerve cell bodies were found in both myenteric and submucous plexuses. The submucous plexus was composed of external and internal ganglionated plexuses. Endocrine cells in the epithelium were reactive for NSE. In ganglia of the myenteric plexus, SP‐, VIP‐, ENK‐, SOM‐, NPY‐ and calbindin‐IR varicose and non‐varicose fibres were found around reactive and unreactive cell bodies. Calbindin, ENK‐, SP‐, SOM‐ and VIP‐IR, but not NPY‐IR, nerve cell bodies were observed. The primary and secondary plexuses contained fibres of each type examined. The tertiary plexus was rich in SP‐IR fibres, although ENK‐, NPY‐, SOM‐ and VIP‐IR fibres were also observed. The deep muscular plexus had mainly ENK‐ and SP‐IR fibres and few VIP‐IR fibres, while in the remainder of the circular muscle VIP‐IR fibres predominated. There were few SP‐IR and no ENK‐IR fibres in this layer. The two ganglionated plexuses of the submucosa contained ENK‐, NPY‐, SOM‐, SP‐ and VIP‐IR fibres, but calbindin‐IR fibres were not found. SP‐ and VIP‐IR cell bodies were found in both plexuses. Blood vessels had SP‐, VIP‐ and NPY‐IR fibres around them. SP‐, VIP‐ and a few SOM‐IR pbres innervated the mucosa, while endocrine cells were found with SP‐, SOM‐ and NPY‐IR. The present study demonstrated that the distribution of the neuropeptides SP‐ and VIP‐IR is similar in the small intestine of the black‐capped capuchin to that in the dog, guinea pig, human and rat. SP‐ and VIP‐IR possibly mark neurons of the same function in each species. Distributions of ENK‐, NPY‐, SOM‐ and calbindin‐IR differ substantially between species.