Effect of Diet Restriction on the Survival of Myenteric Neurons in Jejunum of Aging Male Albino Rat. Histological and Immunohistochemical Study

Introduction: Dysfunctions of the gastrointestinal system are more common complaints of the elderly. Enteric neurons are known to be vulnerable to age related cell death. So, the aim of this study was to study the effect of diet restriction on the histological changes in the myenteric neurons of jejunum of aged male albino rat. Materials and Methods: Thirty male albino rats of 6 months were used. Group I was the control group. Subgroup Ia included 5 rats of 6 months and subgroups Ib and Ic included 5 animals each and were continued to live up to the age of 12 and 18 months, respectively. Group II included 10 rats which were early fed the restricted diet (25 gm diet/rat/ day) and subdivided into two subgroups five animals each. Subgroup IIa were fed the restricted diet starting from 6 to 12 months. Subgroup IIb were fed the restricted diet starting from 6 to 18 months. Group III included 5 rats that were lately fed the restricted diet from 12 to 18 months. At time of sacrifice all the animals were anaesthetized, the jejunum was dissected out and specimens were processed for histological examination. Immunohistochemical expression of the pan-neuronal marker PGP 9.5 and neuronal nitric oxide synthase (nNOS) was investigated. Results: As age advances in subgroup Ib and Ic there was increased neuronal loss and obvious gaps in the myenteric ganglia with significant decrease in the number of PGP positive neurons. Animals of subgroup IIa and IIb showed that most of the myenteric neurons maintained their usual structural arrangement and expression of PGP. In group III rats showed neuronal loss and significant decrease in the PGP positive neurons. There was non significant decrease in the number of nNOS positive neurons in all groups. Conclusion: The results of the current study revealed that age related change involved mainly the cholinergic neurons and starting diet restriction early at 6 months age might slow or delay the age related damage of the rat myenteric neurons.