Prostaglandin H synthase immunoreactivity localized by immunoperoxidase technique (PAP) in the small intestine and kidney of rabbit and guinea-pig

Summary Prostaglandins and inhibitors of prostaglandin synthesis have striking regulatory effects on intestinal muscularis externa. We suggested earlier that a population of macrophage-like cells, located between the external muscle layers might release prostaglandins with a local effect on enveloping interstitial cells of Cajal, postulated pacemaker cells of the gut.To determine cellular production site(s) of prostaglandin we applied monoclonal antibodies against prostaglandin H synthase combined with the PAP technique to sections of rabbit and guinea-pig small intestine and kidney. In rabbit small intestine muscle cells in the circular muscle layer and in the muscularis mucosae were positive, longitudinal muscle negative. Vascular endothelial cells and serosal mesothelial cells were stained. In guinea-pig all muscle layers were unstained but endothelial and mesothelial cells were stained together with unidentified cells in the outermost submucosa. In rabbit kidney, positive staining of collecting ducts, interstitial cells, the parietal layer of Bowman's capsule and arterial endothelial cells was present. Furthermore, we found prostaglandin synthase antigenicity in the epithelial cells lining the loop of Henle, not described before. In guinea-pig medullary collecting ducts were stained and the papilla was lined by stained epithelial cells.The results show a species variation in the distribution of recognizable levels of prostaglandin H synthase. The impressive reaction in the mesothelium must be considered, when enzyme distribution is examined biochemically with fractionated tissue. Our findings do not support our hypothesis that macrophage-like cells are more potent sources of prostaglandins than smooth muscle cells.     

Tyrosine hydroxylase- and neuropeptide Y-immunoreactive nerve fibers in the pineal complex of untreated rats and rats following removal of the superior cervical ganglia

Summary The distribution of tyrosine hydroxylase (TH)- and neuropeptide Y (NPY)-immunoreactive(IR) nerve fibers in the pineal complex was investigated in untreated rats and rats following bilateral removal of the superior cervical ganglia. In normal animals, a large number of TH- and NPY-IR nerve fibers were present in the pineal capsule, the perivascular spaces, and intraparenchymally between the pinealocytes throughout the superficial pineal and deep pineal gland. A small number of TH-IR and NPY-IR nerve fibers were found in the posterior and habenular commissures, a few fibers penetrating from the commissures into the deep pineal gland. To elucidate the origin of these fibers, the superior cervical ganglion was removed bilaterally in 10 animals, and the pineal complex was examined immunohistochemically. Two weeks after the ganglionectomy, the TH-IR and NPY-IR nerve fibers in the superficial pineal gland had almost completely disappeared. On the other hand, in the deep pineal and the pineal stalk, the TH-IR and NPY-IR fibers were still present after ganglionectomy. These data show that the deep pineal gland and the pineal stalk possess an extrasympathetic innervation by TH-IR and NPY-IR fibers. It is suggested that the extrasympathetic TH-IR and NPY-IR nerve fibers innervating the deep pineal and the pineal stalk originate from the brain.