[A qualitative and quantitative analysis on the development of NKA-immunoreaction in duodenum of rats]

To explore the expression and change of neurokinin A (NKA) in rat duodenum during development.

PAP immunocytochemistry method and image analysis were used to detect systematically the expression of NKA in rat duodenum from day 13 of embryo to adult stage.

In rat duodenum, the NKA-IR was first found in the myenteric plexus at day 14 of embryo, and then was found in the longitudinal muscle layer, circular muscle layer, intestinal villus, mucosa plexus, intestinal gland, muscularis mucosae, submucosa, submucosal plexus and deep muscular plexus. At day 30 after birth, the distribution feature of adult rat was seen. The results of quantitative analysis were in accord with the developmental change of NKA-IR in duodenum. The NKA-IR positive cells showed the typical feature of morphology and distribution of gastrointestinal endocrine cells.

The ontogeny and development of NKA in rat duodenum mainly appear at 1 week before birth and at 4 weeks after birth, whereas the density of positive fiber in villus is not the same as adulthood until 60 days after birth. There are two key periods during the development of NKA in rat duodenum. The first crucial stage is from 1 week before birth to 1 week after birth. The second important stage is in the end of the 4th week after birth. The NKA-IR cells may be the endocrine cells that produce NKA in rat digestive tract. NKA may play an important role in the development of rat duodenum, and may be closely related to the functional establishment of duodenum.