Underfed Animals Research Articles

The release of LH at oestrus in ewes on two planes of nutrition during lactation.

Departments of Animal Science and Biochemistry, University of Natal, Pietermaritzburg, South Africa The anoestrous condition which follows upon periods of underfeeding in ewes is apparently similar to the normal seasonal anoestrus and is usually manifested as a prolongation (Hunter, 1962) or precipitated onset (Smith, 1962) of the seasonal period of sexual rest. It has been suggested that the ovarian quiescence noted in underfed animals may be the result of pseudohypophysectomy (Mulinos & Pomerantz, 1940; Lamming, 1966; Leathem, 1966). An acute release of LH at oestrus in ewes has been demonstrated by Niswender, Roche, Foster & Midgley, 1968; Goding, Catt, Brown, Kaltenbach,Cumming & Mole, 1969; Wheatley & Radford, 1969) and it is possible that changes in the pattern of LH release may indicate functional changes in the pituitary of ewes which become anoestrous after periods of inanition. This phenomenon was studied in an attempt to elucidate the mechanism involved in a

Vulnerability of Developing Brain: Relative Effects of Growth Restriction during the Fetal and Suckling Periods on Behavior and Brain Composition of Adult Rats

Growth restriction was achieved by underfeeding mother rats during pregnancy and lactation. Offspring were either ( i ) adequately nourished during the fetal and suckling periods, (ii) undernourished during both, or (iii) and (iv) undernourished during one or the other period. All rats were fed ad libitum from weaning. The post- natally underfed animals were the most efficient at running a maze for a food reward. Differences in levels of motivation were sought using a Skinner box in which rats learned to press a lever for food. Normal rats had the lowest lever-pressing rate and those re stricted both pre- and postnatally had the highest. The tendency to inhibit movement to avoid an electric shock was weakest in normal rats and greatest in the doubly deprived animals. As in the Skinner box test, rats undernourished during only one period occu pied intermediate positions. This is taken to indicate that, with respect to these two measures of behavior, the effects of undernutrition in the fetal and suckling periods were additive. Evidence for an additive effect on physical brain growth is confined to fore- brain DNA-P content, which was substantially reduced by both periods of growth retardation. Cerebellum DNA-P and weights of cerebellum and forebrain were all much more affected by the postnatal treatment. J. Nutr. 103: 1327-1338, 1973.

Vulnerability of developing brain. II. Effects of early nutritional deprivation on reflex ontogeny and development of behaviour in the rat

During the last two weeks of pregnancy and throughout lactation the food intake of a group of female rats was restricted to about half that of a control group fed ad libitum. The growth, physical maturation and behavioural development of control and undernourished male offspring were compared. At 21 days the body weight of the underfed young was only one-third that of controls. The appearance of 2 out of 3 physical features, and of 4 out of 8 reflexes was significantly delayed in the undernourished group. Generally, characteristics which normally appear in the first week of postnatal life were not significantly affected; whereas most of those appearing later were significantly delayed. When rats were 9, 13, 17 and 21 days old their behaviour in an open field was observed. Exploratory responses were first seen significantly later in undernourished young. Though they moved about the field as much as the controls, they made significantly fewer upward-directed responses on the first 3 days of testing. At 21 days most control rats were able to move round the rim of a plastic beaker to a refuge platform, a feat accomplished by only a few underfed animals.

Effect of early underfeeding on the weight of the White Carneau pigeon: With some remarks on the possible inhibition of early atherosclerosis

The growth of the White Carneau pigeon has been studied and a method of significantly underfeeding the squabs during the preweaning period has been developed. The growth of 160 squabs was analyzed at weekly intervals till 6 weeks, then at 8 weeks, and at 6 months. The animals grew remarkably from an average of 22.2 g at hatch to 187.9 at 1 week, 389.3 at 2 weeks, 494.8 at 3 weeks, and 519.4 at 4 weeks. Growth was slow thereafter, reaching 568.6 g at 6 months when the animals are considered to be adult. Underfeeding was accomplished by feeding the mother and father one-third their normal diet during the preweaning 4-week period. The weight reduction was considerable, the squab weighing 21.9 g at hatch, 135.4 at 1 week, 212.8 at 2 weeks, 271.9 at 3 weeks, and 388.7 at 4 weeks. Nonetheless, there was rapid catch-up growth, the animals at 6 months weighing 557.7 g. Forty-two squabs (27 normally fed and 15 underfed) had to be sacrificed for various reasons, such as defective limbs. Pathological analysis of the aorta at the bifurcation of the thoracic aorta at the coeliac axis indicated that the early atherosclerotic lesion had a delayed onset in the underfed animals. In the 27 normally fed animals, Grade 1 lesions were present at 7 weeks, and by 12 weeks, the lesion was usually Grade II. At 24 weeks, the atherosclerotic lesion was often Grade III. In the 15 underfed squabs, no Grade I lesion was seen till 14 weeks and there was one Grade II lesion at 30 weeks.

Some effects of prolonged undernutrition on carbohydrate metabolism in rats.

A) Rats fed 10 gm of ground Rockland diet/day for 4–6 weeks and then fasted for 24 hours showed an enhanced insulin sensitivity as compared with ad libitum-fed rats that were fasted for the same length of time. The fasting blood sugar and liver glycogen concentrations were significantly higher in underfed animals. B) Underfed rats were fasted 24 hours, then fed 5 gm/ 100 gm body weight and tested 8 hours later. These rats exhibited a) no greater insulin sensitivity, b) lower blood sugar levels and c) a smaller rise in liver glycogen concentration than similarly treated ad libitum-fed animals. Intestinal absorption of glucose was not diminished in the undernourished rats. C) Cortisone treatment (0.5 mg/100 gm body wt/day for 5 days) abolished the insulin sensitivity of underfed rats without altering the hepatic glycogen concentration. Somatotrophin (0.5 mg Armour standard equivalent/100 gm body wt/day for 5 days) did not improve their insulin tolerance. After functional evisceration, the blood sugar fall (if expressed as percentage of the initial level) was significantly slower in underfed than in ad libitum-fed rats. However, the decline of the blood sugar level appeared to be more markedly enhanced by insulin in the underfed animals.

EFFECT OF CHRONIC INANITION ON THE GONADOTROPHIC CONTENT OF THE PITUITARY GLAND

Chronic or acute inanition interrupts the sexual cycle in the albino rat, and is associated with regressive changes in the ovaries. Similar effects have been described in other animals, and 'war amenorrhea' and sterility are well known to occur among severely malnourished women. The decreased amount of gonadotrophins in the urine of these women and the fact that oestrus can be re-established in underfed animals by either pituitary or chorionic gonadotrophins suggests that anoestrus is not due to primary ovarian dysfunction but to lack of gonadotrophic hormones. This view is supported by various authors, but surprisingly enough only a few of them have endeavoured to measure the actual gonadotrophic power of the anterior lobe during inanition, and this only by the implantation method, which is liable to considerable experimental error as shown by the discrepancies in the results. In the present work, after verification of the oestrus-inhibiting effect of inanition

Relative Lack of Myelin in Optic Tracts as Result of Underfeeding in the Young Albino Rat.

Summary and ConclusionsQuantitative limitation of food intake sufficient to account for average body-weight differences of 55% between underfed and litter-mate control rats, has also resulted in statistically significant differences in myelination of the optic tracts and nerves. The concentration of myelin in the optic tracts of the underfed rats has averaged 20% less than that in the control animals. Since myelination of the optic tracts, as shown by spectrophotometric determinations in litter-mate rats at successively older ages, is not complete until sometime between the 40th and 50th days, the conclusion seems justified that the relative lack of myelin observed in the underfed animals is due to partial or complete arrest of the process of myelination.

The Effect of Nutritional Deficiencies on the Development of Neutralizing Antibodies and Associated Changes in Cerebral Resistance against the Virus of Western Equine Encephalomyelitis

Summary The influence of underfeeding, deficiency of the whole “B” complex, thiamin-deficiency, riboflavin-deficiency, carbohydrate-deficiency and protein-deficiency was studied with respect to its effect on the development of immunity in mice vaccinated with formalinized Western equine encephalomyelitis mouse brain virus. Immunity was determined by the development of cerebral resistance and of neutralizing antibodies. The latter were quantitatively determined by the method of serum dilution as well as the usual method employing undiluted serum. Mice were given three doses of vaccine of 0.3 ml each intraperitoneally on three alternate days and were tested two weeks after the first dose. Underfed mice developed considerable immunity but not to the same extent as did those on an adequate diet. The well-nourished vaccinated mice resisted between 100 and 200 times more virus intracerebrally than did the underfed animals. The test for neutralizing antibodies likewise showed a significant difference between undernourished and well-nourished mice, with the well-nourished animals neutralizing between 10 and 100 times as much virus as did the starved mice. The serum of the adequately nourished animals could be diluted between 3 and 8 times more than that of the serum obtained from the undernourished mice and still neutralize the effects of a constant amount of virus (50 LD50 doses). Prolonging the period of starvation for an additional two weeks did not accentuate the depressed immunity response. There was no difference in the immune response of animals on a synthetic diet and those on a stock diet. Removal of the whole “B” complex from the synthetic diet yielded equivocal results regarding the immune response in mice, but a decreased ability on the part of “B”-deficient animals to produce antibodies appeared possible. In one case the “B”-deficient animals developed a neutralization index which was 15 fold less than that of the control animals and no difference when the diluted serum was tested against a constant amount of virus and in the other case no difference between neutralization indexes occurred but this time the serum from adequately fed animals could be diluted six times more than that of the “B”-deficient animals and still neutralize the effects of a constant amount of virus. Thiamin- or riboflavin-deficiency had no effect either on the production of neutralizing antibodies or on the development of cerebral resistance. Protein- or carbohydrate-deficiency did not cause a marked failure on the part of deficient animals to develop immunity but there was a quantitative difference. The cerebral immunity was about ten fold greater in the well-nourished than in the deficient mice. The neutralization index of the serum from the well-nourished animals was twenty fold greater and the serum could be diluted three to four times more and still neutralize the effect of 50 LD50 doses of virus in mice.

THE ENDOCRINE SYSTEM AND HAIR GROWTH IN THE RAT

The literature dealing with the influence of endocrine organs on hair growth is not extensive, and the results reported are by no means concordant. In the rat there seems to be a specific influence of the thyroid gland, the administration of which accelerates hair growth in some normal animals, but not all, whereas underfed animals respond more uniformly [Chang, 1926; Chang & Feng, 1929]. Chang & Feng [1929] also noted that thyroidectomy slows the rate at which new hair grows, and found no difference in response between the sexes. They measured the time elapsing before growth on a shaved patch appeared to be complete. Butcher [1940] found that thyroxin and various irritants such as xylene or capsicum decreased the time elapsing before the first appearance of new hair in underfed albino rats, whereas well-fed animals were not much affected. Freud [1934] found that normal, thyroidectomized, epiphysectomized and castrated male rats

THE RELATION OF THE ADRENALS TO THE RETARDED HAIR GROWTH IN UNDERFED ALBINO RATS

APREVIOUS PAPER (I) contained statistics showing to what extent hair growth in rats was affected by underfeeding. When the quantity of feed was reduced so that little body weight was gained the body increased in length, but hair growth was delayed. Since some skeletal growth occurred in these underfed animals, building factors were present in the body. It would, therefore, seem that in all probability the retarded hair growth was due to the deviation of factors from the hair follicles. Since a precocious hair growth occurred in well fed adrenalectomized rats (2), and adrenals hypertrophied in underfed animals (3, 4), it occurred to the authors that the adrenal might be responsible for this retardation of hair growth upon underfeeding. Investigations were accordingly undertaken in underfed animals to see if adrenalectomy would induce hair growth and if there were any indications that the adrenals changed and caused the retarded effect.

Experimental results bearing on the etiology of cystic growths in the ovary and uterus of the guinea pig

In experiments on underfeeding it was found that malnutrition readily gave rise to marked cystic conditions in the ovaries of healthy young guinea pigs. Such cystic conditions are, of course, frequently found in normal stock but here especially in old or unhealthy specimens.The changed nutritive conditions in the reproductive organs of underfed animals cause circulatory congestion, and as was pointed out in a previous communication1 such conditions suppress the œstrous changes and prevent ovulation in these animals. The congestion and the high pressure resulting therefrom seem to favor the proliferation of the epithelial lining of the epididymal tubules located near one pole of the ovary, and the accumulation of fluid within the lumen of the blind tubules.The malnutrition expresses itself first within the ovary by a wholesale degeneration of developing follicles which seem to respond most delicately to changes in nutritive conditions. The congestion and follicular degeneration seem then to favor an overgr...