Immunohistochemical evidence of vanilloid receptor 1 in normal human urinary bladder.

PURPOSE: Experimental and clinical evidences have shown the importance of the vanilloid receptor 1 (TRPV1) in the lower urinary tract. In humans, this receptor has been detected in nerve endings of primary sensory neurons, smooth muscle and connective tissue cells and in the rat also in the urothelium. The aim of this study is to identify, by immunohistochemistry, the cell types expressing TRPV1 in the human urinary bladder. MATERIAL AND METHODS: Specimens, obtained from normal urinary bladder by multiple biopsy and from ureter at the time of radical nefrectomy for renal cell carcinoma, were fixed and frozen. Full-thickness sections were processed for light and fluorescence microscopes. To label the TRPV1, three polyclonal antibodies were used: the anti-capsaicin receptor, the anti-VR1 (N-15) and the anti-VR1 (C-15). RESULTS: Urothelium, smooth muscle cells, mast cells and endothelium were labelled and the labelling was intracytoplasmatic. In the urothelial cells, the labelling was slightly granular. In the bladder urothelium, the superficial cells were more intensely stained than the basal and club-shaped cells. VR1-positive nerve fibers were seen running single and/or in groups in the sub-urothelium and as single varicose fibers in the muscle coat, and VR1-positive nerve endings in the urothelium. CONCLUSION: The present findings provide the evidence of the presence of TRPV1 on normal human urothelium where it could have important implications in the mechanism of action of intravesical vanilloids (capsaicin and resiniferatoxin).

Neurofilament formation and synaptic activity are delayed in the myenteric neurons of the rat fetus with gastroschisis.

Gastroschisis is a malformation characterized by prenatal evisceration of the midgut into the amniotic cavity. Because of the harmful effects of the amniotic fluid, the intestinal loops appear matted, thickened, and covered by a peel. At birth, the newborn presents altered intestinal motility. In a previous publication, we reported a delay in the myenteric ganglia organization and neuronal maturity in a rat model of gastroschisis. In the present study, the neurofilament formation and synaptic activity were immunohistochemically investigated in the myenteric neurons of this animal model. The expression of low, medium and high molecular weight neurofilament proteins and of a protein of the synaptic vesicles, the synaptophysin, were similar to those found at earlier embryonic ages. These findings demonstrate delayed cytoskeletal organization and reduced synaptic activity in the myenteric neurons in the rat model of gastroschisis.

Ultrastructural changes in the interstitial cells of Cajal and gastric dysrhythmias in mice lacking full-length dystrophin (mdx mice).

At least two populations of c-kit positive interstitial cells of Cajal (ICC) lie in the gastric wall, one located at the myenteric plexus level has a pace-making function and the other located intramuscularly is intermediary in the neurotransmission and regenerates the slow waves. Both of these ICC sub-types express full-length dystrophin. Mdx mice, an animal model lacking in full-length dystrophin and used to study Duchenne muscular dystrophy (DMD), show gastric dismotilities. The aim of the present study was to verify in mdx mice whether: (i) gastric ICC undergo morphological changes, through immunohistochemical and ultrastructural analyses; and (ii) there are alterations in the electrical activity, using intracellular recording technique. In control mice, ICC sub-types showed heterogeneous ultrastructural features, either intramuscularly or at the myenteric plexus level. In mdx mice, all of the ICC sub-types underwent important changes: coated vesicles were significantly more numerous and caveolae significantly fewer than in control; moreover, cytoskeleton and smooth endoplasmic reticulum were reduced and mitochondria enlarged. c-Kit-positivity and integrity of the ICC networks were maintained. In the circular muscle of normal mice slow waves, which consisted of initial and secondary components, occurred with a regular frequency. In mdx mice, slow waves occurred in a highly dysrhythmic fashion and they lacked a secondary component. We conclude that the lack of the full-length dystrophin is associated with ultrastructural modifications of gastric ICC, most of which can be interpreted as signs of new membrane formation and altered Ca(2+) handling, and with defective generation and regeneration of slow wave activity.

Interstitial cells of Cajal, enteric neurons, and smooth muscle and myoid cells of the murine gastrointestinal tract express full-length dystrophin.

A gene located on the X chromosome is responsible for the transcription of several mRNA and related dystrophin isoforms. Lack or truncated expression of the 427-kDa, full-length isoform in skeletal muscle results in Duchenne muscular dystrophy (DMD). Patients with DMD, as well as mdx mice, a mutant strain also lacking this isoform, show gastrointestinal dismotilities. The present aim was to identify the cell types that express full-length dystrophin in the gastrointestinal tract. An immunohistochemical study was performed using an antibody specific for this isoform, and double labelings were made for interstitial cells of Cajal (ICC) identification and to verify whether all neurons express full-length dystrophin. Three different fixation procedures were used. The results showed that ICC, enteric neurons, and smooth muscle and myoid cells expressed full-length dystrophin. In ICC and neurons, dystrophin-immunoreactive patches were irregularly distributed at the cell contour and within the cytoplasm. In smooth muscle and myoid cells, regularly spaced dystrophin-immunoreactive bars were located along the cell contour. Labeling intensity varied according to fixation procedure. The different subcellular distributions of dystrophin immunoreactivity might reflect diverse roles played by full-length isoforms in each cell type. Dystrophin loss in cells involved in gastrointestinal motility might explain the gastrointestinal symptomatology affecting DMD patients and mdx mice.