Differential gene expression and immune localization of the orexin system in the major salivary glands of pigs

► The orexinergic system is expressed differently among major salivary glands of pigs. ► Prepro-orexin mRNA was more expressed in the sub-mandibular gland. ► Immunoreactivity for orexins and receptors were identified only in the sub-mandibular gland. ► Striated ducts and parasympathetic neurons and axons of gland ganglia were positive.