Effects of pre- and postnatal protein deprivation and postnatal refeeding on myenteric neurons of the rat small intestine: a quantitative morphological study.

We investigated weight gain, the size of the small intestine and numbers and sizes of enteric neurons in rats whose mothers had been deprived of protein during pregnancy and who themselves were deprived postpartum. Postnatally, protein deprivation was for 42 days, or for 21 days with refeeding for a further 21 days. Control animals received normal nourishment. Neurons were located by nicotinamide adenine dinucleotide (NADH) diaphorase staining, by acetylcholinesterase (AChE) activity and immunoreactivity for choline acetyltransferase (ChAT). The collagen and elastic fibers in the myenteric ganglia were evaluated histologically. The myenteric ganglia were regular and uniform in the nourished and refed groups. In the undernourished group, the myenteric ganglia were irregularly arranged and the cytoplasm of most of the neurons showed less intense staining for NADH diaphorase, AChE and ChAT. AChE activity and ChAT immunoreactivity showed that most ganglionic neurons were stained in nourished and refed groups, but the neurons of undernourished rats were unstained or moderately stained. The distribution of the connective tissue of the ganglionic capsule was similar in the three groups. There was a decrease in weight of undernourished rats, which was restored in refed rats. The size of the small intestine of the undernourished group was smaller than in the normally fed group, by about 45%, but it was similar in nourished and refed rats. After 42 days of protein deprivation the numbers of neurons that were revealed by NADH diaphorase were fewer than in well nourished rats, but numbers were not different between nourished and refed rats. These observations indicate that protein deprivation alters histological features and acetylcholinesterase activity of neurons and also reduces body weight but these were restored by refeeding.