The rate and degree of food compensation on alteration of its caloric density in rats.

The ability to regulate energy level by male albino rats on administration of food with varying caloric densities, was studied. The animals fed different caloric density diets exhibited marked variations in their caloric in take in the initial stages which stabilized after 5 to 10 days and maintained on lower mean caloric intake on diet having density of 2.63 Kcal/gm, and higher mean caloric intake on diet with density of 4.88 Kcal/gm. Similar variations in body weight were also evident with failure to maintain the body weight with caloric dilution.

Effects of adrenalectomy on brain weight, body weight and weight of certain endocrine organs in rats.

Albino rats, both males and females were adrenalectomized (Adx.), either on the eleventh or the twenty fifth day after birth and the body weights recorded daily until the sixtieth day when all the animals were sacrificed. Brain (cerebrum and cerebellum), pituitary, thyroid and gonads were weighed post mortem. Body weights decreased in all the Adx. animals, the decrease being statistically significant in the male rats Adx. on day 11 (p less than 0.05). Both cerebrum and cerebellum recorded a significant increase in weight in both the male Adx. groups, whereas pituitary, thyroid and gonads showed a significant decrease. Changes observed in 25 day Adx. female rats were not statistically significant. Thus, adrenalectomy in the young rats appears to have differential effects on the somatic, neural and endocrine growth.

Ingestive behaviour of starved rats after single intraperitoneal injection of fresh plasma from well-fed rats.

Ingestive behaviour of control and experimental rats following 96 hours of starvation was studied. The control animals were injected normal saline intraperitoneally (I.P.) whereas the experimental animals were injected I.P. with fresh plasma obtained from well fed rats. Having been presented with food 15 minutes after the injections, the food intake (Gms +/- SEM) of control animals for the first five hours after injection was 6.00 +/- 0.44, whereas, the intake in experimental animals for the same period was 0.55 +/- 0.05. The food intake was significantly suppressed for the next three days, attaining the normal values by the 4th day. Since all the rats were starved prior to injection, all of them increased in weight during the four days of study, but the increase seen in the experimental group was much subdued. Therefore the plasma factor, suppresses not only the food intake but also the gain in body weight.

Effect of immobilization stress on food intake, body weight and weights of various organs in rat.

Effect of immobilization stress was studied in male albino rats. Experimental rats (E) were restrained in close-fitting wiremesh cylinders. Control rats (C) were not subjected to restraint. Food and water were made available to C for all the 24 hrs while the E were given them for only 6 hrs daily. The initial lower food intake of E was later reversed to near normal levels. There was a steady fall in the body weights of E, while the C displayed a normal growth rate. Cerebrum, cerebellum, pituitary and adrenals of E weighted significantly more. There was an apparent increase in the weight of thyroid. Gonads displayed no change in weight. The results indicate that chronic restraint causes loss of body weight inspite of a near normal food intake. It also produces an increase in the weight of brain, and certain endocrine organs.

Effect of stress on maternal behaviour.

Primiparous female rats subjected to foot shock and/or immobilization stress were tested for maternal behaviour (MB) by determining the pup retrieval rate (PRR) for 5 minutes. On the third day after parturition PRR significantly decreased when foot shock was given and the fall was more pronounced after immobilization both with and without foot shock. The animals exhibited enhanced MB on the 12th day as compared to the third day, but the stressful situations produced significant decreases in MB qualitatively similar to the third day. By the 20th day when the weaning was in progress the MB decreased to the 3rd day levels. This change in the MB may be due to the changes in the pattern of prolactin secretion during the post partum period.

Role of mid-dorsal caudate nucleus in maintenance of body weight in rats on administration of foods with different caloric densities.

Rats were fed with food of different caloric densities by addition of kaolin or groundnut oil to the normal food powder. The food intake, caloric intake and body weights were noted. These observations were compared before and after bilateral destruction of mid-dorsal caudate nucleus. The food intake before caudatal lesion varied appropriately with the caloric density of food thus maintaining caloric intake and body weight. After mid-dorsal caudatal destruction this feedback mechanism of maintaining body weight was operative with low caloric density diet but not with high caloric diet.