Nitric Oxide Synthase Immunoreactivity and NADPH-d Histochemistry in the Enteric Nervous System of Sarda Breed Sheep With Different PrP Genotypes in Whole-mount and Cryostat Preparations

Abstract

Until now, significant differences in the neurochemical pattern of enteric neurons have been demonstrated in all species studied; however, some strong similarities also occur across species, such as the occurrence of nitric oxide synthase immunoreactivity (NOS-IR) in inhibitory motor neurons to muscle. In consideration of the insufficient data regarding the enteric nervous system (ENS) of sheep, we investigated the myenteric plexus and submucosal plexus of the ovine ileum. Since the pivotal role of the ENS in the early pathogenesis of sheep scrapie, the “prototype” of prion diseases, has been suggested, we have focused our observations also on the host's PrP genotype. We have studied the morphology and distribution of NOS-IR neurons and their relationships with the enteric glia in whole-mount preparations and in cryostat sections. NOS-IR neurons, always encircled by glial processes, were located in both plexuses. Many NOS-IR fibers were seen in the circular muscle layer, in the submucosa, and in the mucosa. In the submucosa they were close to the lymphoid tissue. No differences in the distribution and percentage of NOS-IR fibers and neurons were observed among sheep carrying different PrP genotype, thus making unlikely their contribution in the determinism of susceptibility/resistance to scrapie infection.

Anatomical evidence for ileal Peyer’s patches innervation by enteric nervous system: a potential route for prion neuroinvasion?

“…Studies of PP innervation in cattle (Balemba et al 1999) and pigs (Krammer and Kühnel 1993) have failed to reveal any nerve fibres within lymphoid follicles, probably because fibres reaching PPs are extremely thin and/ or show low levels of immunoreactivity (IR). By contrast, other investigations in cattle (Defaweux et al 2007), pigs (Kulkarni-Narla et al 1999), cats (Feher et al 1992), hamster (Pfoch and Unsicker 1972), mouse (Ottaway et al 1987;Defaweux et al 2005;Ma et al 2007), rat (Shtylik et al 1998), rabbit (Driessen et al 1992) and sheep (Heggebø et al 2003;Press et al 2004;Lalatta-Costerbosa et al 2007) have revealed innervation inside PP follicles. Recent investigations have demonstrated the presence of a dense neuronal network at the level of suprafollicular dome region, but not within the germinal centers, in porcine jejunal (Green et al 2003;Vulchanova et al 2007) and human ileal (Vulchanova et al 2007) PPs.…”

Myenteric neurons of the ileum that express somatostatin are a target of prion neuroinvasion in an alimentary model of sheep scrapie

“…In sheep, mucosal nerve Wbers include those that express VIP, SP, NOS [8,27,51], and also SOM (Fig. 7).…”

Quantitative changes of nitrergic neurons during postnatal development of chicken myenteric plexus

“…Dawson et al (1991) has previously reported that NOS staining is identical to NADPH-d staining. NADPH-d staining has been used in recent studies to qualify and quantify nitrergic neurons in the gut in different species: mice (Azzena and Mancinelli, 1999), rats (Sandgren et al, 2003), guinea-pigs (Wade et al, 2003), sheep (Lalatta-Costerbosa et al, 2007), rabbits (Junquera et al, 1998), dogs (Ward et al, 1992), pigs (Cserni et al, 2009b), cats (Feher and Montagnese, 1994), monkeys and humans (Degiorgio et al, 1994;Wittmeyer et al, 2010), pigs, guinea-pigs, and rats (Bodi et al, 2009), andchicks (O′Donnell et al, 2006). The whole-mount preparation technique allows the observation of the 3D meshwork of the myenteric plexus and quantitative and qualitative analyses of the myenteric neurons (Wester et al, 1999).…”