Glucocorticoids as counterregulatory hormones of leptin: toward an understanding of leptin resistance.

The product of the ob gene, leptin, is a hormone secreted by adipose tissue that acts in the hypothalamus to regulate the size of the body fat depot. Its central administration has been shown to decrease food intake and body weight, while favoring energy dissipation. As glucocorticoids are known to play a permissive role in the establishment and maintenance of obesity syndromes in rodents, it was hypothesized that they do so by restraining the effect of leptin.

Adrenalectomy prevents the obesity syndrome produced by chronic central neuropeptide Y infusion in normal rats.

Neuropeptide Y (NPY) in the hypothalamus plays an important role in the regulation of food intake and body weight and seems to be implicated in the etiology of obesity. When intracerebroventricularly (ICV) infused for 6 days in normal rats, NPY resulted in hyperphagia, increased body weight gain, hyperinsulinemia, hypercorticosteronemia, and hypertriglyceridemia compared with vehicle-infused control rats. NPY infusion also resulted in an insulin-resistant state in muscles and in a state of insulin hyperresponsiveness in white adipose tissue, as assessed by the measurement of the in vivo glucose utilization index of these tissues during euglycemic-hyperinsulinemic clamps.

The loop system between neuropeptide Y and leptin in normal and obese rodents.

Over the years, the work of research laboratories in Baton Rouge (USA), Seattle (USA) and Geneva (Switzerland) have reached analogous conclusions regarding the main etiology of obesity as studied in animals: it largely lies within the brain, notably within the hypothalamus. The hypothalamus is indeed known to modulate food intake and energy partitioning, while the periphery has also been proposed to feed-back on the central nervous system (CNS) to provide information on the state of body energy stores, the two together constituting a loop system connecting the brain to the periphery (1,2,3). This etiologic viewpoint of a pivotal role of the hypothalamus in obesity syndromes has been strengthened by the discovery of one hypothalamic neuropeptide and one peripheral (adipose tissue) hormone, respectively neuropeptide Y (4), and quite particularly, leptin (5).

Diagnosis and treatment of a parasitic dermatitis in a laboratory colony of African clawed frogs (Xenopus laevis).

A parasitic dermatitis, caused by a nematode infestation of the epidermis, was diagnosed in 11 captive African clawed frogs (Xenopus laevis) by a histological examination of the skin. Eight of the animals died or were euthanased before effective treatment with levamisole was administered, and one frog died after being treated. Secondary infection with opportunistic pathogens may have been involved in the progression of the disease.

Acute intracerebroventricular administration of neuropeptide Y stimulates corticosterone output and feeding but not insulin output in normal rats.

The effect of acute intracerebroventricular (i.c.v.

Intracerebroventricular administration of neuropeptide Y to normal rats increases obese gene expression in white adipose tissue.

The aim of this work was to determine the possible inter-relationship between neuropeptide Y (NPY, a hypothalamic stimulator of feeding) and adipose tissue expression of the ob protein (a novel potent inhibitor of feeding). Such a relationship could be of importance in the maintenance of normal body weight. To this end, normal rats were intracerebroventricularly (i.

Health and welfare of rehabilitated juvenile hedgehogs (Erinaceus europaeus) before and after release into the wild.

Thirteen wild caught juvenile hedgehogs were treated and overwintered in a rehabilitation centre and 12 were released into the wild and monitored by radiotelemetry. Clinical examinations were carried out before they were released and twice afterwards, and any hedgehogs found dead were examined post mortem. The health of the animals was generally good but dental disease, obesity and minor injuries were common.

The ob gene and insulin. A relationship leading to clues to the understanding of obesity.

Obesity and non-insulin-dependent diabetes are estimated to affect millions of people in the world. This pathology is multifactorial, comprising complex interactions of genetic and environmental factors and lacking a specific therapy. Great interest arose from the recent discovery of the ob gene expressed only in adipose tissue and coding for a protein that appears to regulate adiposity, potentially by acting as a satiety factor.

An investigation into the health and welfare of red squirrels, Sciurus vulgaris, involved in reintroduction studies.

The threats posed by parapoxvirus infection, metabolic bone disease and coccidiosis to the reintroduction of red squirrels into Thetford Chase were investigated by making blood biochemical, radiological and parasitological examinations on the squirrels before they were released and on resident squirrels. Red squirrels found dead in Thetford Chase were examined post mortem by parasitological, electron microscopical and radiological techniques. Parapoxvirus infection was the probable cause of death of two red squirrels.

Lipid and apolipoprotein B48 transport in mesenteric lymph and the effect of hyperphagia on the clearance of chylomicron-like emulsions in insulin-deficient rats.

In insulin-deficient streptozotocin-treated rats the intestine is hypertrophic and cholesterol synthesis and transport from the intestine are increased. The increased load of cholesterol is transported through the mesenteric lymph in chylomicrons. Clearance from plasma of injected chylomicrons is slowed in insulin-deficient rats, but the underlying mechanisms are currently unresolved.

Effects of galactose feeding on aldose reductase gene expression.

Aldose reductase (AR) is implicated in the pathogenesis of the diabetic complications and osmotic cataract. AR has been identified as an osmoregulatory protein, at least in the renal medulla. An outstanding question relates to the response of AR gene expression to diet-induced galactosemia in extrarenal tissues.

Retrovirally-produced erythropoietin effectively induces differentiation and proliferation of J2E erythroid cells.

The J2E erythroid cell line terminally differentiates in response to recombinant human erythropoietin (rHu-epo). Here we demonstrate that retrovirally produced monkey erythropoietin (Zen-epo) is also capable of inducing the final maturation steps of J2E cells in a dose-dependant manner. The hormone committed J2E cells to a pathway of accelerated proliferation, haemoglobin synthesis and morphological changes including enucleation.

Clonal analysis of erythropoietin stimulated J2E cells reveals asynchrony during terminal differentiation.

J2E erythroid cells proliferate and differentiate in response to erythropoietin (epo), the red blood cell specific hormone. Using methylcellulose colony assays and suspension cultures we have demonstrated that nearly all the cells stimulated by epo synthesized haemoglobin. To achieve maximum production of haemoglobin J2E cells had to be treated with epo for only 6 h; hormone added subsequently did not enhance haemoglobin synthesis.

Hypertriglyceridemia is exacerbated by slow lipolysis of triacylglycerol-rich lipoproteins in fed but not fasted streptozotocin diabetic rats.

Hydrolysis by endothelial lipases of triacylglycerol-rich lipoproteins of diabetic origin were compared to lipoproteins of non-diabetic origin. The plasma lipoprotein fraction of density < 1.006 g/ml, including chylomicrons and VLDL, were incubated in vitro with post-heparin plasma (PHP) lipases.

Age determination of common marmosets (Callithrix jacchus) by radiographic examination of skeletal development.

Seventy-four animals were examined radiographically to determine the skeletal development of the common marmoset (Callithrix jacchus) from 6 months of age. Twenty-one epiphyses were examined and five stages of ossification were described for each. The animals were divided into nine groups, according to age, and a table of the stage of ossification and age was produced, which may be used for determining the age of animals of unknown history.

Restraint and anaesthesia of primates.

The methods available for the restraint and anaesthesia of captive primates are discussed, emphasising the differences between the techniques for primates and those for other mammals; the importance of humane methods of physical restraint is emphasised. The agents available for chemical restraint and surgical anaesthesia are considered in terms of their ease of administration, the dose rate required, speed of induction and recovery, analgesic properties, muscle relaxation and side effects. New agents are available which are potentially useful in primates.