title: Cholinergic and noncholinergic innervation of the smooth muscle layers in the bovine abomasum.
abstract: The intrinsic innervation of muscle layers in the mammalian gastrointestinal tract has been mainly studied in nonruminants. The aim of this study was to identify intrinsic motor neurones in the bovine abomasum that innervate the circular and longitudinal muscles. Circular (CMN) and longitudinal muscle motor neurones (LMN) were selectively labeled by application of the retrograde tracer 1,1'-didodecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate (DiI) onto the muscle layers. The transmitter phenotype was determined by immunohistochemical detection of choline acetyltransferase (ChAT), nitric oxide synthase (NOS), and neurone-specific enolase (NSE). On average, the myenteric ganglia contained 61 +/- 19 NSE-positive cell bodies, of which 89% were ChAT-positive and 10% were NOS-positive. Only 0.7% of NSE-positive neurones (41 of 5,777) contained both ChAT and NOS. Application of DiI onto the circular and longitudinal muscles revealed on average 60 +/- 27 (n = 4) and 68 +/- 36 (n = 4), respectively, labeled cell bodies in the myenteric plexus. For the circular and longitudinal muscles the proportions of ascending to descending neurones were 76 : 24% and 54 : 46%, respectively. While most ascending CMN were ChAT-positive (96%), 51% of the descending CMN were ChAT-negative. All ascending and 95% of descending LMN were ChAT-positive. It was concluded that cholinergic excitatory innervation is predominant in both muscle layers of the abomasum. Whereas the circular muscle receives cholinergic excitatory and nitrergic inhibitory innervation, the longitudinal muscle is only innervated by cholinergic pathways. This innervation pattern is different from that in gastric muscle layers in monogastric animals.
authors: Veterinär-Physiologisches Institut, Veterinärmedizinische Fakultät, Universität Leipzig, Leipzig, Germany. pfannku@rz.uni-leipzig.de
authors: Helga
authors: H
authors: Pfannkuche
authors: Dania
authors: D
authors: Reiche
authors: Susanne
authors: S
authors: Hoppe
authors: Michael
authors: M
authors: Schemann
mesh_terms: D000018:Abomasum / Q000294:innervation*; D000818:Animals; D002232:Carbocyanines; D002417:Cattle; D002795:Choline O-Acetyltransferase / Q000032:analysis; D002799:Cholinergic Fibers / Q000201:enzymology / Q000502:physiology*; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D009046:Motor Neurons / Q000166:cytology / Q000201:enzymology; D009130:Muscle, Smooth / Q000294:innervation*; D009197:Myenteric Plexus / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000032:analysis
chemical_list: C035005:3,3'-dihexadecylindocarbocyanine; D002232:Carbocyanines; D005456:Fluorescent Dyes; D019001:Nitric Oxide Synthase; D002795:Choline O-Acetyltransferase