Quantification and morphometry of myenteric neurones in the jejunum of Holtzman rats (Rattus norvegicus).

UNLABELLED: With 2 figures and 3 tables SUMMARY: The morphological pattern of the myenteric plexus (MP) is species-specific, and little is known about this pattern in Holtzman rats. The aim of the current experiment was the morphological and quantitative study of myenteric neurones in the Holtzman rat jejunum. Hematoxylin-Eosin and NADH-diaphorase (NADH-dp) staining were used to assess muscular layer thickness, neurone cell body area (CBA) and nuclei area (NA). Muscular layer thickness was found to be 114.77 ± 14.89 µm. Neuronal densities across the subregions of the jejunum were similar: mesenteric, 11.78 ± 2.89/mm(2) ; intermediate, 12.06 ± 2.69/mm(2) ; and antimesenteric, 10.67 ± 1.89/mm(2) . As expected, there was positive correlation between the CBA and NA of 79.19, 79.26 and 78.5% in the mesenteric, intermediate and antimesenteric subregions of the jejunum, respectively. Medium-sized neurones predominated in the ganglionic arrangement of the MP. These results indicate that the NADH-dp myenteric neurones in the jejunum of Holtzman rats are similar in many aspects to those found in the ileum of Holtzman rats and to those found in the small intestine of Wistar rats, including their location, ganglionic disposition and predominance of medium-sized CBA. However, neuronal density in the jejunum is lower than in the ileum. Based on these results showing morphological similarities to the MP of the Wistar rat, the Holtzman strain can be used to investigate the effects of adverse conditions on the morphology of the MP.

Effects of the ingestion of 2, 4 Dichlorophenoxyacetic acid on jejunal myenteric neurons in rats

2,4 dichlorophenoxyacetic acid (2,4-D) is a systemic herbicide. The effects of different levels of 2,4-D on some animal organ systems have been examined, but little is known about its role in the enteric nervous system. The purpose of this study was to verify the effects of 2,4-D administration on the density and morphometry of jejunal myenteric neurons in rats. Ten male rats were assigned to control (C) and experimental (E) groups. For 15 days, group E received, via gavage, 5 mg of 2,4-D.kg–1 body weight. On the 16th day, the animals were sacrificed by a lethal dose of thiopental, and the jejunum was removed by laparotomy and used to obtain whole mount preparations for Giemsa staining and NADPH-diaphorase (NADPHd+) histochemistry to identify neurons. The density and cell body area of the myenteric neurons was measured. In the total neuronal population, the neuronal density/mm2 of the jejunum in groups E and C was equivalent, and the cell body area of the rats in group E was lower (p < 0.05) than that of those in group C. For NADPHd+ neurons, the neuronal density did not differ between the groups, although the cell body area was larger (p < 0.05) in group E. It was concluded that even though 2,4-D does not alter the neuronal density in the rat jejunum, it induces cell body atrophy in the general population of neurons and hypertrophy of the NADPHd+ nitric oxide producing neurons without promoting cell death.