Evaluation of density and distribution of CART-immunoreactive structures in gastrointestinal tract of hypertensive rats.

The prevalence of CART (cocaine- and amphetamine-regulated transcript) throughout the organism, multiplicity of functions fulfilled by that peptide, and the collected evidence confirming CART contribution to blood pressure regulation prompted us to undertake the research aiming to identify, localize, and assess changes in CART-immunopositive structures of the gastrointestinal tract (GI tract) of rats with renovascular hypertension. The two-kidney one-clip model of arterial hypertension was used to evaluate the location and density of CART-containing structures in the stomach (cardia, fundus, and pylorus), duodenum, jejunum, ileum, and colon of hypertensive rats. The study was carried out on the GI tract of 20 rats. Ten rats were subjected to the renal artery clipping procedure and after a 6-week period each of them developed stable hypertension. An immunohistochemical localization of CART was performed on paraffin GI tract sections from all the study animals. CART was detected in the extensive population of neurons, particularly within the myenteric plexuses all along the GI tract, and also in neuroendocrine cells, being especially numerous in the stomach and a few in the small intestine. The hypertension significantly increased the density of CART-positive structures in the rat GI tract. The differences between the hypertensive rats and the control animals concerned not only the density of CART-immunoreactive structures but also the staining intensity. As this study provides novel findings, we are planning further molecular examinations to better understand the impact of hypertension on the functioning and activity of CART in the GI tract.