Benefits of caloric restriction in the myenteric neuronal plasticity in aging rats

Abstract

Aging is a biologic process characterized by progressive damage of structures and functions of organic systems. In gastrointestinal tract, it can involve enteric nervous system, which plays an important role in digestion and absorption of nutrients, causing hastening of intestinal transit thus reducing its absorptive function. Caloric restriction has been used in several studies with the intention of delaying deleterious effects of aging. This study aimed to evaluate the effects of caloric restriction on myenteric neurons of ileum by aging in rats. 30 Wistar rats were grouped as follows: GI (animals aged 6 months fed with normal diet), GII (animals aged 18 months fed with normal diet) and GIII (animals aged 18 months subject to 31% of caloric restriction). The rats of the GI group were euthanized at 6 months of age and after experimental period of 12 months animals of the group GII and GIII were euthanized, the ileum of all groups were collected, measured and processed by NADPH-dp and Acetylcholinesterase. Quantitative analysis of neurons revealed that aging promotes the increasing of myenteric neurons NADPH-dp and reduces Acetylcholinesterase neuronal population. However, in the cellular profile area, were not observed significant differences between the groups. The caloric restriction has been efficient and can be used preventively because it minimizes quantitative changes associated with aging on ileum myenteric plexuses.

The ageing gastrointestinal tract

“…The myenteric plexus modulates the contractility of the smooth muscles that line the gastrointestinal tract and is fundamental to gut transit. Ageing is associated with a decrease in the total number and density of enteric nerve fibres, particularly in the myenteric plexus [7,25,31,32]. The two major groups of myenteric neurons are cholinergic neurons, which are excitatory, and nitrergic neurons, which are inhibitory.…”

“…Ageing is associated with structural changes of the pancreas, as well as decreased concentrations of lipase in the pancreatic juice [7,25], which could have the potential to compromise absorption of lipids. For example, in older (25 months old) compared with younger (3 months old) mice, serum triacylglycerol concentrations increased 5% less after soybean oil ingestion [40].…”

“…The latter may be linked to frailty and sarcopaenia to systemic disorders, such as diabetes and depression, and to degenerative disorders affecting the central nervous system, such as Parkinson's disease and multiple sclerosis [4 & ]. In rodent studies, caloric restriction (30-50%) may help prevent deleterious effects of ageing of the gastrointestinal tract by promoting changes in gene expression, increased capacity for DNA repair, reductions of oxidative stress and enteric neuronal death, and protection against myenteric neuronal loss, particularly in the proximal colon [6][7][8]. However, caloric restriction can also lead to hypertrophy of the smooth muscle layer of the gut in older (24 months old) compared with younger (7 and 12 months old) rats, which may potentially compromise the neuromuscular function in the colon [8].…”

The effects of quercetin on liver regeneration after liver resection in rats

“…One reason is certainly the fact that during the aging process comes to changes in the size of the digestive tract. This is particularly evident in animal experimental models in which certain influences on cellular aging may include living conditions and diet [25,32]. It also must be taken into account that the various types of animals used in the research have different natural life span.…”

Small intestine remodeling in male Goto–Kakizaki rats

“…We estimated the total number of myenteric and submucosal neurons in the small intestine by multiplying the number of cells/ mm 2 by the previously determined serosal surface area. We measured the areas of 100 neuronal cell bodies (μm 2 ) per segment per animal using a semi-automatic morphometric device (Pereira et al, 2014), totaling 500 neurons in each intestinal segment per group.…”