NOS immunoreactivity in the reticular groove of lamb

Evidence suggests that the reticular groove (RG) may have an important role as the coordinating center of reticuloruminal motility. The aim of this study was to investigate the presence and distribution of nitric oxide synthase (NOS) neurons and their phenotype in the RG of suckling lamb. Using double immunohistochemistry, NOS neurons were found along the entire length of RG and were most abundant in the distal part of the floor. They showed irregular profile and often co-localized with galanin, never colocalized with substance P, while few colocalized with choline acetyl-transferase, dopamine β-hydroxylase or tyrosine hydoxylase. No enteric neurons expressed neuropeptides normally found in intrinsic primary sensory neurons such as calcitonin gene related peptide or calbindin. Nitrergic neurons represent a predominant component involved in the inhibition of RG motility.