Depletion Of Body Fat Research Articles

Timing of eclosion affects diapause development, fat body consumption and longevity in Osmia lignaria, a univoltine, adult-wintering solitary bee

Most insects from temperate areas enter diapause ahead of winter. Species diapausing in a feeding stage and accumulating metabolic reserves during permissive pre-wintering conditions are expected to enter diapause shortly before the onset of winter. In contrast, species diapausing in a non-feeding stage are expected to lower their metabolism as soon as possible to avoid excessive consumption of metabolic reserves. The solitary bee Osmia lignaria winters as a non-feeding adult within its cocoon, but previous studies show important weight losses and increased winter mortality in populations pre-wintered for extended periods. We measured respiration rates to assess diapause initiation and maintenance during pre-wintering, and tested whether timing of adult eclosion affected fitness by measuring fat body depletion, winter mortality and post-winter longevity. We worked with different cohorts of a population reared under natural conditions, and manipulated pre-wintering duration in a population reared under artificial conditions. In agreement with our expectation, O. lignaria lower their metabolic rates within a few days of adult eclosion, but nonetheless suffer strong weight loss during pre-wintering. Early developing individuals suffer greater weight loss and fat body depletion, and have short post-winter longevity. Although, we found no differences in winter mortality among treatments, our results indicate that increased mortality may occur in years with late winter arrivals. We discuss fundamental ecophysiological differences between adult and prepupal diapause within the Megachilidae, and hypothesize that species wintering as adults will be more negatively affected by a situation of extended summers under a scenario of global warming.

Increased Bone Marrow Fat in Anorexia Nervosa

Although women with anorexia nervosa (AN) have severe depletion of body fat, a paradoxical increase in bone marrow fat has been described. Recent data suggest that marrow fat measured by 1H-magnetic resonance spectroscopy (MRS) in combination with bone mineral density (BMD) may be more valuable than either parameter alone in detecting bone weakness. The objective of the study was to investigate the effect of AN on accumulation of marrow fat in spine and femur using 1H-MRS and the relationship between marrow fat, BMD, and body composition in subjects with AN and normal-weight controls. This was a cross-sectional study. The study was conducted at a referral center. Patients included 10 women with AN (29.8 +/- 7.6 yr) and 10 normal-weight age-matched women (29.2 +/- 5.2 yr). There were no interventions. Marrow fat content of the fourth lumbar vertebra and femur measured by 1H-MRS. BMD of spine and hip measured by dual-energy x-ray absorptiometry. Subjects with AN had higher marrow fat at the fourth lumbar vertebra and femur compared with controls (P = 0.004-0.01). There was an inverse correlation between marrow fat of L4 and femur and BMD of the spine and hip (r = -0.56 to -0.71, P = 0.01-0.0002) and body mass index and sc adipose tissue of the thigh (r = -0.49 to -0.71, P = 0.03-0.0007). There was an inverse correlation between femur marrow fat and sc and total abdominal adipose tissue (r = -0.53 to -0.67, P = 0.003-0.03). Women with AN have greater lumbar and femoral marrow fat than controls, and marrow fat correlates inversely with BMD. This paradoxical increase in marrow fat at a time when sc and visceral fat are markedly reduced raises important questions about functional consequences of this process.

EFFECTS OF SUMMER‐AUTUMN NUTRITION AND PARTURITION DATE ON REPRODUCTION AND SURVIVAL OF ELK

: Recent declines in numbers and juvenile recruitment in many elk (Cervus elaphus) herds in the western U.S. has sparked interest in factors that may cause these declines. Inadequate nutrition or delayed parturition, the latter of which may be caused by inadequate numbers of mature bulls (i.e., highly skewed sex ratios), may have separate or synergistic effects on population dynamics and productivity. We evaluated the implications of late parturition and summer-autumn nutrition on reproduction and survival of Rocky Mountain elk (C. e. nelsoni) using a captive herd of 57 cow elk. We induced early (Sep) and late breeding (Oct) and 3 levels of summer-autumn nutrition on the cows. Food was offered ad libitum at 3 levels of digestible energy (DE): high = 2.9-3.0 kcal of DE/g of diets, medium = 2.6-3.0 kcal/g, and low = 2.3-3.0 kcal/g. Within these ranges, DE content was gradually reduced from late June through early November to mimic seasonal changes in the wild. During summer and autumn, we measured calf growth; body mass, nutritional condition, and breeding dynamics of cows; and growth and pregnancy of yearlings. We also measured carry-over (i.e., time-lag) responses including over-winter calf and cow survival and parturition date and birth mass, as functions of previous summer-autumn nutrition and previous parturition date. Between autumn 1995 and spring 1998, we conducted 2 years of parturition-date, summer-autumn nutrition experiments, 2 winters of calf survival experiments, and 1 winter of cow survival experiments. Early birth provided calves with more time to grow before onset of winter. This “head-start” advantage was maintained through late autumn, but its magnitude was diluted in some instances due to faster growth of some late-born calves. Body mass, body fat, and timing and probability of conception by cows in autumn were little influenced by parturition date the previous spring. Summer-autumn nutrition significantly affected calves and their mothers. Growth of calves in the low and medium nutrition groups ceased by mid-September and late October. By December, calves in the high nutrition group were 40% and 70% heavier than calves in the medium and low groups, respectively. Cows in the high nutrition group accumulated about 75% and 300% more fat than cows in the medium and low groups by mid-October. Eighty percent of cows in the low nutrition group failed to conceive, and those in the medium group bred 10–14 days later than cows in the high group. Summer-autumn nutrition of calves influenced their probability of becoming pregnant as yearlings. Probability of pregnancy approached 100% for those yearlings that had high summerautumn nutrition as calves and yearlings, despite near starvation their first winter of life. Winter survival of calves was related to their size at the onset of winter. Smaller calves lost more body mass daily than did large calves, and thus they survived fewer days through winter. Summer-autumn nutrition largely determined calf body size at the start of winter and, consequently, determined the proportion of winter survived. Survival of cows over winter was as related to body fat at the onset of winter as it was to nutrition during winter. Carry-over effects of summer-autumn nutrition and parturition date on birth characteristics the following spring were minor. We detected no significant carry-over effect of summer-autumn nutrition or autumn condition on birth mass, although reduced condition in autumn delayed subsequent parturition date. Extent of body fat depletion in cows during the winter-survival experiments in 1998 accounted for 45% of the variation in parturition date. Ninety percent depletion delayed parturition an average of 34 days. Delayed parturition, of a magnitude expected due to highly skewed sex ratios (3 weeks under extreme conditions), probably has only a weak influence on vital rates of free-ranging elk. In contrast, fat accretion and probability of pregnancy of cows, and growth and overwinter survival of calves, were sensitive to small (10–20%) differences in DE content of food. Digestible energy levels of our 2 lower nutrition levels reflect DE ranges reported for large ungulate herds during summer and autumn in western North America. Thus, our data suggest that limiting effects of summer-autumn nutrition on populations may be greater than often assumed, perhaps greater than those during winter in some ecosystems, and consequently indicate a need for greater understanding of nutrition's influence on population dynamics and how this influence varies across space and time. To enhance future research, we present animal- and vegetation-based guidelines for evaluating nutritional influences on elk populations.

Effect of Wintering Duration and Temperature on Survival and Emergence Time in Males of the Orchard PollinatorOsmia lignaria(Hymenoptera: Megachilidae)

We measured winter survival, emergence time following incubation at 20°C, and postemergence longevity in males of the orchard pollinator Osmia lignaria Say exposed to 25 artificial wintering treatments differing in duration (30, 90, 150, 210, and 270 d) and temperature (0, 4, 7, 10, and 13°C). For all temperatures, survival was highest at 90 d of wintering. Temperatures ≥10°C were unsuitable for wintering O. lignaria populations even for short periods. At 7°C, bees showed increased mortality, signs of excessive fat body depletion, and decreased longevity when wintered for >150 d. Wintering durations ≥210 d required temperatures ≤4°C for acceptable survival. Time to emerge following incubation at 20°C decreased with increasing wintering duration and wintering temperature. Many bees emerged before incubation when wintered for long periods at the warmest temperatures. Postemergence longevity was highest when bees were wintered at 0°C for 210 d. Managing the activity of O. lignaria to coincide with fruit tree bloom initiation is much more easily accomplished with the use of populations exhibiting short emergence times. Several wintering treatments that resulted in acceptable survival and longevity (150 d at 0, 4 and 7°C, and 210–270 d at 0 and 4°C), produced mean emergence times ≤5 d. Our results can be used to establish appropriate wintering regimes for O. lignaria populations managed to pollinate orchard crops differing in bloom time (from almonds in February to apples in May), and therefore, allowing for shorter or longer wintering durations.

Alcohol consumption promotes body weight loss in melanoma-bearing mice.

Alcohol consumption is an important risk factor for cancer. Little is known about its effects on cancer progression. Previously, we showed that high ethanol consumption inhibited metastasis of B16BL6 melanoma-bearing mice without affecting primary tumor growth. On the other hand, ethanol-consuming tumor-bearing (TE) mice exhibited decreased survival and decreased body weight as compared to water-drinking, tumor-bearing (TW) mice. The focus of this study was to determine how alcohol promotes weight loss in melanoma-bearing mice. Female, C57BL/6 mice were given water or 20% w/v ethanol in the drinking water for 3 weeks to 6 months before subcutaneous inoculation of 1 x 10(6) B16BL6 melanoma cells. Mice continued to receive the same fluids. Biochemical parameters were evaluated at various times after tumor inoculation. Body weight, water content, tumor weight and carcass fat content were determined at necropsy. TW mice elicted a modest weight loss. This response was magnified 2-fold by alcohol consumption. The weight loss in TE mice is not caused by dehydration, decreased energy intake, or loss of skeletal muscle mass. It resulted specifically from loss in body fat. Other alterations associated with the fat loss in TE mice were: (1) decreased glucose, (2) elevated fatty acids, (3) elevated beta-hydroxybutyrate, (4) elevated glucagon, and (5) increased leptin levels in plasma. Body temperature decreased about 2.9 degrees C in TE mice. Metabolic rate increased in TW mice. The fat loss due to alcohol consumption in tumor-bearing mice was not due to increased metabolic rate. The response elicited by alcohol consumption in tumor-bearing mice is complex and associated with alterations in metabolism and hormones. These findings suggest that alcohol abuse could be a risk factor for cancer patients because it invokes a strong depletion of body fat. This could facilitate wasting and shorten survival time.

Alcohol Consumption Promotes Body Weight Loss in Melanoma‐Bearing Mice

Background: Alcohol consumption is an important risk factor for cancer. Little is known about its effects on cancer progression. Previously, we showed that high ethanol consumption inhibited metastasis of B16BL6 melanoma‐bearing mice without affecting primary tumor growth. On the other hand, ethanol‐consuming tumor‐bearing (TE) mice exhibited decreased survival and decreased body weight as compared to water‐drinking, tumor‐bearing (TW) mice. The focus of this study was to determine how alcohol promotes weight loss in melanoma‐bearing mice.Methods: Female, C57BL/6 mice were given water or 20% w/v ethanol in the drinking water for 3 weeks to 6 months before subcutaneous inoculation of 1 × 106 B16BL6 melanoma cells. Mice continued to receive the same fluids. Biochemical parameters were evaluated at various times after tumor inoculation. Body weight, water content, tumor weight and carcass fat content were determined at necropsy.Results: TW mice elicted a modest weight loss. This response was magnified 2‐fold by alcohol consumption. The weight loss in TE mice is not caused by dehydration, decreased energy intake, or loss of skeletal muscle mass. It resulted specifically from loss in body fat. Other alterations associated with the fat loss in TE mice were: (1) decreased glucose, (2) elevated fatty acids, (3) elevated β‐hydroxybutyrate, (4) elevated glucagon, and (5) increased leptin levels in plasma. Body temperature decreased about 2.9°C in TE mice. Metabolic rate increased in TW mice. The fat loss due to alcohol consumption in tumor‐bearing mice was not due to increased metabolic rate.Conclusions: The response elicited by alcohol consumption in tumor‐bearing mice is complex and associated with alterations in metabolism and hormones. These findings suggest that alcohol abuse could be a risk factor for cancer patients because it invokes a strong depletion of body fat. This could facilitate wasting and shorten survival time.

How the immune and nervous systems interact during disease-associated anorexia

Anorexia is one of the most common symptoms associated with illness and constitutes an adaptive strategy in fighting acute infectious diseases. However, prolonged reduction in food intake and an increase in metabolic rate, as seen in the anorexia-cachexia syndrome, lead to depletion of body fat and protein reserves, thus worsening the organism’s condition. Because the central nervous system controls many aspects of food intake, soluble factors known as cytokines that are secreted by immune cells might act on the brain to induce anorexia during disease. This review focuses on the communication pathways from the immune system to the brain that might mediate anorexia during disease. The vagus nerve is a rapid route of communication from the immune system to the brain, as subdiaphragmatic vagotomy attenuates the decrease in food-motivated behavior and c-Fos expression in the central nervous system in response to peripheral administration of the proinflammatory cytokine, interleukin-1β, or bacterial lipopolysaccharide. At later time points after peripheral lipopolysaccharide administration, interleukin-1 itself acts in the brain to mediate anorexia and is found in the arcuate nucleus of the hypothalamus. The mechanisms by which interleukin-1β gains access to the brain and the potential role of neuropeptide-Y-containing neurons in the arcuate hypothalamus in mediating anorexia during disease are discussed.

Human leptin regulation and promise in pharmacotherapy.

In rodents leptin inhibits food intake, stimulates energy expenditure, reverses obesity, ameliorates insulin resistance, and accelerates sexual maturation. These potent and diverse effects have stimulated interest in exploring a role for leptin in the treatment of human metabolic disorders. However, the significance of leptin in human (patho)physiology is still being investigated. The present review summarizes current knowledge of leptin regulation, provides a critical assessment of initial experience with leptin therapy, and discusses potential targets for recombinant leptin therapy in humans. The results of numerous studies indicate that leptin is indeed a regulated human hormone: The physiological factors that influence leptin secretion include gender, adiposity, physical exercise, feeding, and caloric restriction. Several hormones, including insulin, glucocorticoids, estradiol, growth hormone, testosterone, somatostatin, and insulin-like growth factor-I also modulate leptin secretion. The results of initial trials of leptin therapy in humans have become available. Treatment with recombinant human leptin (0.028 mg/kg) induced a progressive weight loss (without evidence of tachyphylaxis) in a morbidly obese patient with congenital leptin deficiency. The weight loss averaged 1-2 kg/month, was associated with preservation of lean muscle mass, and was almost exclusively accounted for by depletion of body fat. Administration ofrecombinant leptin (0.01-0.3 mg/kg) also resultedin a dose-dependentweight loss among lean and obese humans with presumably normal leptin genotype. Thus leptin may have a therapeutic role in humans, but its physiological functions and regulation first need to be fully unravelled.

Evidence for Reproductive Diapause in the Fritillary <I>Speyeria idalia</I> (Lepidoptera: Nymphalidae)

Reproductive characteristics of a northeastern Kansas population of the fritillary Speyeria idalia (Drury) were studied. Hemolymph juvenile hormone (JH) titers, ovarian development, and fat body utilization were monitored weekly in adult females over their entire 1997 flight period, which extended from mid-June to early October. Dissections of female reproductive systems revealed that S. idalia females mate just once, soon after they emerge in mid- to late June. Gas chromatographic-mass spectrometric determinations of juvenile hormone suggested that they undergo a reproductive diapause through mid-August related to the absence of or very low titers of juvenile hormone. Oogenesis and fat body depletion do not commence until late August/early September, soon after which oviposition occurs. The onset of oogenesis coincides with a rapid rise in hemolymph titers of JH I, JH II, and JH III. The predominant juvenile hormone homolog was JH II, but both JH I and JH III exhibited smaller, concomitant peaks. Four fundamentally different lepidopteran reproductive strategies have been recognized based on various reproductive characteristics and the type of gonadotropic hormones used to stimulate oogenesis. Speyeria idalia exhibits a type of reproductive strategy that has not been documented in Lepidoptera, typified by protandry, female monandry, long-lived (>8 wk) females that feed throughout their adult lives, greatly delayed oogenesis that occurs late in adult life, and apparent juvenile hormone control of gonadotropic processes. This reproductive strategy appears to be an adaptation to the phenology of larval host plants, namely coordinating the life cycle with that of the seasonally restricted violets on which larval survival of this monophagous species depends.

Effect of a leucine-supplemented diet on body composition changes in pregnant rats bearing Walker 256 tumor.

Cancer patients present high mobilization of host protein, with a decrease in lean body mass and body fat depletion occurring in parallel to neoplastic growth. Since leucine is one of the principal amino acids used by skeletal muscle for energy, we investigated the changes in body composition of pregnant tumor-bearing rats after a leucine-supplemented diet. Sixty pregnant Wistar rats divided into six groups were fed a normal protein diet (18%, N) or a leucine-supplemented diet (3% L-leucine, L). The pregnant groups were: control (CN), Walker 256 carcinoma-bearing rats (WN), control rats pair-fed with tumor-bearing rats (pfN), leucine-supplemented (CL), leucine-supplemented tumor-bearing (WL), and leucine-supplemented rats pair-fed with tumor-bearing rats (pfL). At the end of pregnancy, all animals were sacrificed and body weight and tumor and fetal weight were determined. The carcasses were then analyzed for water, fat and total, collagen and non-collagen nitrogen content. Carcass weight was reduced in the WN, WL, pfN and pfL groups compared to control. The lean body mass and total carcass nitrogen were reduced in both tumor-bearing groups. Despite tumor growth and a decrease in fetal weight, there was a slight decrease in collagen (7%) and non-collagen nitrogen (8%) in the WL group compared with the WN group which showed a decrease of 8 and 12%, respectively. Although the WL group presented severe tumor growth effects, total carcass nitrogen and non-collagen nitrogen were particularly higher in this leucine-supplemented group compared to the WN group. These data suggest that the leucine-supplemented diet had a beneficial effect, probably attenuating body wasting.

Hypothalamic CART and serum leptin levels are reduced in the anorectic ( anx/anx) mouse

Cocaine- and amphetamine-regulated transcript (CART) is expressed in the hypothalamus, and putative peptides encoded by CART potently inhibit feeding when administered centrally. CART is strongly down-regulated in the lateral hypothalamic area and the arcuate nucleus in animal models of obesity with disrupted leptin signaling. Here we have used in situ hybridization and immunohistochemistry to study CART expression in mice homozygous for the anorexia ( anx) mutation which are characterized by a much reduced food intake and premature death. anx/anx mice had significantly decreased levels of CART mRNA label and peptide-immunoreactive cell bodies and fibers in the arcuate nucleus and a lower number of detectable CART-expressing cells in the dorsomedial hypothalamic nucleus/lateral hypothalamic area. Moreover, serum leptin levels were significantly lower in anx/anx mice compared to normal littermates, most likely due to the prominent depletion of body fat in these animals. The decrease in the anorexigenic agents leptin and CART, may reflect a compensatory down-regulation in response to the energy-deprived state of anx/anx mice. Alternatively, the reduced arcuate CART expression may be a consequence of a molecular defect in the arcuate nucleus of these animals.

Modulation of leptin sensitivity by short photoperiod acclimation in the Djungarian hamster, Phodopus sungorus.

During seasonal acclimation, Djungarian hamsters spontaneously exhibit a reduction in food intake, body mass and body fat stores, which is externally cued by shortening of day length in autumn and controlled by a sliding set-point. We investigated the function of the leptin adipostatic feedback system in the photoperiodic control of seasonal acclimation. In response to mouse recombinant leptin injections for 10 days, long day photoperiod (LD) and short day photoperiod (SD)-acclimated hamsters decreased food intake and body mass. The reduction of body mass was due to the depletion of body fat, as revealed by carcass composition analysis. In SD hamsters, leptin caused a larger reduction of body fat mass than observed under LD conditions, whereas the anorectic effect was similar in both photoperiods. The serum leptin concentration was 9.3 +/- 1.2 ng/ml in LD-acclimated hamsters and decreased significantly to 4.2 +/- 0.8 ng/ml and 2.1 +/- 0.6 ng/ml in hamsters exposed to SD for 66 days and 116 days, respectively (P < 0.001). A strong positive correlation between total body fat mass and serum leptin concentration was found (rS = 0.935, P < 0.0001, n = 70). Despite the anorectic action of exogenous leptin, higher endogenous leptin levels in LD hamsters were paralleled by higher food intake in LD hamsters as compared to SD hamsters. This paradoxical finding further supports the increased leptin sensitivity in SD hamsters as judged from leptin treatment experiments. We tested the functional significance of leptin for the controlled down-regulation of food intake and body mass induced by short photoperiod. Food restriction for 10 days during the transition phase decreased body mass below the desired sliding set-point, which was recovered in control hamsters following ad libitum refeeding. Treatment with mouse recombinant leptin during ad libitum refeeding inhibited the recovery of body mass and blunted the increase of food intake observed in controls, indicating that the sliding set-point utilizes leptin as a signal for the adjustment of the appropriate body mass level.

Plasma leptin decreases during lactation in insectivorous bats

We previously demonstrated high leptin levels during late pregnancy in little brown bats (Myotis lucifugus). We now extend these observations to a second species, the big brown bat (Eptesicus fuscus), and also report that leptin increases after the first trimester of pregnancy. Leptin decreased to baseline 1 week following parturition, with a half-time decay of 2 days. During lactation, leptin was significantly correlated with body mass in E. fuscus, but not in M. lucifugus. No circadian pattern of leptin was observed in M. lucifugus. The decrease in post-partum leptin in bats may be partly explained by loss of putative placental leptin. The continued decrease may reflect depletion of body fat during this energy demanding period, at least in Eptesicus. Changes in leptin during lactation appeared to be independent of circadian effects and time of sampling. Our study provides additional evidence that leptin increases during pregnancy and declines during lactation in a free-ranging mammal, supporting the hypothesis that leptin plays important but yet undetermined roles in reproduction.

Temporal Incidence and Sexual Maturation of Austracris guttulosa (Walker) (Orthoptera: Acrididae) in Queensland, Australia

ABSTRACTLife history data for the cyrtacanthacrid locust Austracris guttulosa in Queensland were compiled from field observations over the period 1971‐1976. Nymphs were present from November to April inclusive and adults throughout the year, with adults from overlapping generations present in January and February. A. gurtulosa was univoltine, adults remaining sexually immature throughout the dry season (April to October). Sexual maturation was related to the higher temperatures, humidities and day lengths from September/October onwards and resulted in depletion of fat body. Sexually mature adults died out by February.

Short day-induced depletion of lipid stores is fat pad- and gender-specific in Siberian hamsters

The naturally occurring, short day (SD)-induced decrease in body mass in male Siberian hamsters is due almost exclusively to decreases in body fat during the first few weeks of SD exposure. This decrease in body fat is not uniformly distributed among the white adipose tissue (WAT) pads. The purpose of the present experiment was to answer four questions: (i) Are the SD-induced preferential decreases in internally located fat pad mass gender specific?; (ii) Does gonadectomy and/or steroid replacement therapy alter this pattern of body fat depletion?; (iii) What is the role of lipoprotein lipase (LPL) activity in this process?; and (iv) Does SD-induced functional castration affect food intake, body mass and lipid-related fat responses similarly to surgical castration? Adult male and female Siberian hamsters were housed in long days (LD) for 6 wk following castration (CAST) or ovariectomy (OVX) combined with either SC implants of testosterone(T), estradiol or the cholesterol control (CHOL). While the remaining animals of both sexes remained gonadally intact. At this time, half the animals in each group were transferred to SDs for 6 wk. SD-housed gonad-intact males and females exhibited gonadal regression and decreased body mass and carcass lipid; however the pattern of lipid depletion from the WAT pads was gender specific. SD-exposed gonad-intact males showed disproportionate decreases in fat pad mass in the internally located epididymal WAT (EWAT) and retroperitoneal WAT (RWAT) fat pads compared with the more externally located intraperitoneal WAT (IWAT) pad, whereas females showed uniform relative decreases for all pads and regardless of their reproductive status. CAST + CHOL or T eliminated the SD-induced fat pad-specific pattern of lipid depletion in males. Therefore, the slowly decreasing serum T concentrations trigged by the initial exposure to SDs may underlie the fat pad-specific differential depletion of lipid. The photoperiod-, gonadectomy-, and hormone replacement therapy-induced changes in fat pad mass were seldom associated with parallel changes in specific LPL activity. CAST and SD exposure both reduce serum T concentrations, decrease body mass via reductions in the same carcass components and decrease food intake; however, these the two treatments differ with respect to their effects on WAT mass and LPL activity. Specifically, SD exposure decreases IWAT, EWAT and RWAT mass, whereas CAST decreases only EWAT mass. In addition, specific LPL activity is not affected by SD exposure, whereas CAST generally increases specific LPL activity in all pads compared to their gonad-intact controls.

Food intake in diabetic rats: Relationship to metabolic effects of insulin treatment

Hyperphagic streptozotocin-diabetic rats were given week-long treatment with 0 (vehicle), 3, or 6 U/rat/day of regular insulin via a SC osmotic pump. Insulin reduced urinary glucose excretion and plasma glucose and increased body weight in a dose-related manner starting on the first day of treatment. Insulin treatment also increased carcass weight, carcass fat, and liver glycogen within 3 days. Food intake did not decrease until the fifth day of insulin treatment, and this change was unrelated to the amount of insulin administered. These results show that the effects of insulin on food intake and metabolism of diabetic rats can be dissociated with respect to both time course and dose of insulin. The findings indicate that hypoinsulinemia, glycosuria, body weight loss, and depletion of body fat and liver glycogen are symptoms of diabetes, not causes of diabetic hyperphagia.

Body composition and reproduction in mountain hares (Lepus timidus scoticus) in north‐east Scotland

Mountain hares in north‐east Scotland are pregnant from Mid‐February to mid‐July, although breeding is at a peak from April to June when all adult females are either pregnant or lactating or both. The onset of reproduction coincides with the highest body fat composition and the end of the breeding season coincides with the greatest depletion of body fat.

Effect of drinking pattern on plasma lipoproteins and body weight

The effect of drinking pattern on plasma lipoproteins and body weight was examined in three groups of squirrel monkeys: (1) controls fed isocaloric liquid diet; (2) regular drinkers given liquid diet containing ethanol (EtOH) substituted isocalorically for carbohydrate at 12% of calories daily; and (3) binge drinkers fed 6% EtOH calories daily for a four-day period followed by three days of 20% EtOH to mimic a weekend bout drinking cycle. The number of calories offered per day was the same for all groups, and the average weekly EtOH consumption (12% calories) was identical for the two alcohol treatments. The entire study lasted six months. There were no significant differences in plasma cholesterol, triglyceride or liver function tests. Regular drinkers had the highest high density lipoprotein 2/high density lipoprotein 3 ( HDL 2 HDL 3 ) protein and apolipoprotein A-I B ratios of any group and exhibited a significant elevation in the molar plasma lecithin: cholesterol acyltransferase (LCAT) rate (nmol/min/ml). Binge drinking produced a selective increase in low density lipoprotein (LDL) cholesterol and apolipoprotein B, and a depression in the fractional LCAT rate (% esterified/min). During the course of the study, controls ate 92% of their diet while the alcohol groups each consumed 95% of the liquid diet. Despite this difference, body weight and Quetelet index (weight/height 2)decreased progressively in the order controls > regular drinkers > binge drinkers. Results from our study indicate that moderate, regular daily consumption of EtOH at 12% of calories causes a modest reduction in body weight and produces a coronary protective lipoprotein profile (↑ HDL 2 HDL 3 , T apolipoprotein A-I B , low LDL cholesterol). By contrast, when this same average weekly dose is concentrated in a binge cycle, unfavorable alterations in lipoprotein composition (↑ LDL cholesterol, ↑ apolipoprotein B) and metabolism (↑ LCAT activity) occur along with weight loss and depletion of body fat. These studies point to the value of the squirrel monkey model in evaluating both favorable and pathophysiological effects of chronic EtOH intake.

The role of octopamine in handling and exercise-induced hyperglycaemia and hyperlipaemia in Acheta domesticus

House crickets, Acheta domesticus, are different from related Orthoptera in that they give a hyperglycaemic and hyperlipaemic response to handling stress and to injections of octopamine instead of either hyperglycaemia (cockroaches) or hyperlipaemia (locusts). The rapid elevation of both lipids and sugars in response to handling stress is probably due to octopamine released into circulation from the head, because the response was eliminated with head ligation. Exercise stress caused a rapid hyperglycaemia and a delayed hyperlipaemia; we suggest that the rapid sugar elevation was due to release of octopamine from the corpora cardiaca and that the delayed elevation of lipids was due to the release of adipokinetic hormone. The age related depletion of fat body reserves through oögenesis appeared to lower the capacity of the cricket to mobilize sugar in response to stress.

Effect of Hypocaloric Stress on Body and Tissue Composition of Rats K

Rats fed ad libitum, a ration comprising fresh foods (F ration) for 10 days, were switched over to another ration consisting of processed foods (P ration) for a similar period. Thereafter, the animals were subjected to a 50 per cent diet restriction for a period of 10 days and rehabilitated either on F ration or P ration for an equal period. The results showed a decline in growth rate, food consumption and food efficiency ratio in the group fed ad libitum on P ration compared to that on F ration. Fifty per cent diet, restriction induced loss of body weight due to depletion of body fat. A fall in the gross weight of liver,kidney and epididymal fat pad along with a reduction in the contentsof lipid in liver and fat pad were also observed. Refeeding ofdiet-restricted rats induced hyperphagia and super-normal weight gainwith both rations. The data on liver triglycerides appeared to show anage-related rise which could be controlled by diet restriction to someextent. Feeding of P ration tended to predisperse to higher adiposetissue cholesterol attributable to higher fat content of this ration.