Hypobaric Hypoxia and Hedonic Matrix in Rats.

Abstract

This study was carried out to evaluate the effect of continuous exposure to hypobaric hypoxia on the feeding behavior and taste responses of rats, under simulated conditions of a high altitude (HA) of 7,620 m for 21 h a day and consecutively for 18 d, which more closely resembles actual field conditions. Their food, water intake and body weight were recorded daily, and blood sugar was estimated once a week. All the parameters were recorded for a period of 18 d each, before, during, and after exposure to simulated HA. The results show a decrease in daily food and water intake and body weight, and mild hypoglycemia during hypoxic exposure. Single-bottle and two-bottle tests showed a preference for sweet solutions over water, citric acid, sodium chloride, and quinine sulfate during exposure. The two-bottle test showed a preference for glucose over calorically-inert saccharine. The continuous exposure in this study produced qualitatively similar but quantitatively accentuated results as compared to intermittent 6 h exposure contiguously for 21 d. High-altitude stress appears to influence food intake such that sensory cues assume greater significance during feeding behavior.

Hypobaric Hypoxia Induces Depression-like Behavior in Female Sprague-Dawley Rats, but not in Males

“…1C) and males ( -5 -3 g, F (3, 44) = 121, p < 0.0001, Fig. 1D) lost weight after a week at 20K, as previously shown at high altitude (Singh et al, 1997).…”

Effect of a carbohydrate supplement on feeding behaviour and exercise in rats exposed to hypobaric hypoxia

“…These findings are clearly in accordance with the reports of Jacobs and Sharma (1969), and Singh et al (1996Singh et al ( , 1997a and clearly demonstrate the altered taste responsiveness under the stress of hypoxia. The total intake of the supplemented group could have been higher but for the fact that they had access to the supplement for only the 3 h that they were outside the chamber.…”

“…It was observed that the animals did not consume much food and water during the exposure period, and the maximum consumption took place during the 3-h period when they were at sealevel. Many researchers have reported anorexia in animals (Tanaka et al, 1997;Vats et al, 1999;Singh et al, 1996;1997a) and in humans (Consolazio et al, 1969;Hannon et al, 1976;Young et al, 1989), who attributed this decrease to loss of appetite. The anorexia observed in the present study was maximum during the first week and showed an improvement after two weeks of exposure.…”

“…Several investigators have used an animal model to study the direct effects of hypoxia on body and muscle growth. Many studies have reported a decrease in the growth rate of rats at least during the first days of exposure to HA (Bigard et al, 1996;Schnakenberg et al, 1971;Singh et al, 1996;1997a). The depression of growth rate has been attributed to anorexia, loss of body water, a direct effect of hypoxia on protein metabolism, or impaired absorption of nutrients (Schnakenberg et al, 1971).…”

“…High-CHO diets have been shown to increase lung pulmonary diffusion capacity (Dramise et al, 1975), increase alveolar and arterial oxygen pressures (Hansen et al, 1972) and improve endurance during HA acclimatization (Young et al, 1982). Earlier studies at our laboratory have also reported a preference for sweet-tasting (carbohydrate) solutions over other taste stimuli in rats subjected to hypoxic stress (Singh et al, 1996;1997a). Similarly, preferences for sweet taste in human volunteers abruptly inducted to HA were also noted (Singh et al, 1997b).…”