Mandibular Growth Retardation in Growing Rats Chronically Exposed to Hypobaria

Abstract

Weanling male Wistar rats aged 21 days were divided into three groups: initial control, normobaric, and hypobaric (C, N, and H, respectively). C rats were killed three days after being weaned. H rats were placed into an altitude chamber and maintained at 456 mb (6100 m) for 14 days. N rats were maintained at sea-level conditions. Body weight, body and tail lengths, and food intake were recorded every day. Animals were killed at the end of the experimental period, and four linear dimensions of the dried mandible were measured. The amount of food eaten by the H rats during the entire exposure period was 54.6% of that consumed by N ones. Body weight gain in H rats was 32.7% of that seen in N rats. Body length was 49.0% and tail length was 56.6% of normal. All mandibular dimensions were significantly reduced in H rats when compared with N rats and were, in general, in close relation with the reduction observed in skeletal growth. Only one dimension was reduced out of proportion, which indicates some deformation of the mandible. The average daily caloric intake related to metabolic body weight (body weight 0.75) of H rats was 60% of the N value. Efficiency of protein utilization for growth was not significantly different between both groups of rats. These results indicate that chronic exposure to hypobaria induces overall skeletal and mandibular growth retardation, which appears to be the result of a diminution in food intake because of decreased appetite.

Effects of exercise training in hypoxia versus normoxia on fat-reducing in overweight and/or obese adults: A systematic review and meta-analysis of randomized clinical trials

“…Highlanders’ negative energy balance was the primary cause of weight loss ( Hamad and Travis, 2006 ). According to animal studies, 21-day-old rats exposed to a low-pressure chamber at a simulated altitude of 6100 m only had 54.6% of the food intake and 32.7% of the body weight gain of normoxic rats ( Bozzini et al, 1987 ). Energy intake was also reduced in humans exposed to artificial hypoxia ( De Glisezinski et al, 1999 ).…”