Activity-induced thermogenesis in lean and genetically obese (ob/ob) mice

Summary Motor activity was approximately 60% lower in genetically obese than in lean mice, during three consecutive hours at thermal neutrality. It is suggested that this must have contributed to the lower heat production measured in the obese mice and that activity-induced thermogenesis contributes significantly to differences in energy expenditure between the genotypes, at least in the short-term.     

Increase in pituitary melanocyte-stimulating hormone activity of genetically obese (ob/ob) mice

Summary Melanocyte-stimulating hormone (MSH) activity was measured in the pituitaries of genetically obese and lean control mice using the frog skin bioassay. Obese mice pituitaries demonstrated very significantly elevated levels of biologically active MSH when compared to their lean littermates. These results support the hypothesis that the elevated levels of pituitary hormones found in obese mice possess true biological activity.     

Dissociation of obesity,hypercholesterolemia and diabetes from atherosclerosis in ob/ob mice

Summary Genetically obese, diabetic and hypercholesterolemic C57BL/6J-ob/ob mice were placed on Purina Laboratory Chow containing 2% cholesterol for up to 4 months. They developed higher plasma cholesterol levels and accumulated an increased quantity of cholesterol in the liver but failed to develop atherosclerotic lesions in the aorta as would be expected in an obese, diabetic and hypercholesterolemic human adult.Acknowledgments. We wish to thank Mr. Willis M. Overton for his excellent technical assistance.     

Stimulation of locomotor activity of genetically obese mice by amphetamine

Zusammenfassung Die motorische Aktivität von genetish obesen (ob/ob) und diabetischen (db/db) Mäusen wurde durchd-Amphetamin stärker gesteigert als bei normalen Mäusen, wobei das Regulationszentrum für die motorische Aktivität intakt zu sein scheint.     

Plasma prostaglandin levels in fed and starved lean,normal and obese women

Summary The plasma obtained from fed and starved lean, normal and obese women was estimated, by a radio-immunoassay method, for prostaglandins, owing to their implication in the regulation of adipose tissue lipolysis and the development of obesity. No significant differences were found due to nutritional status or body-build. However, a significantly higher plasma concentration of prostaglandins of the E-type than of the F-type, was found consistently. The very low levels of prostaglandins observed (a range of 0.10–0.15 ng ml^–1 for E-type and a range of 0.05–0.07 ng ml^–1 for the F-type) may be due, in part, to the activity of a plasmatic prostaglandin metabolizing system.Acknowledgments. The authors are grateful to Dr D.C. Williams for his support and encouragement and to the Upjohn Company for the generous gift of standard prostaglandins.     

Altered brain cholinergic enzymes activity in the genetically obese rat

Summary Genetically obese male Zucker rats (fa/fa) and their lean littermates (Fa/-) were used in this experiment. Fourteen-week-old obese and lean littermates were sacrificed and choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) enzymes were assayed in specific brain regions. The assays of these enzymes indicate that obese animals and a significantly lower ChAT activity in the cerebellum, pons, and cerebral cortex and a significant increase in ChAT activity in the thalamus and hypothalamus. Meanwhile, the cerebral cortex, cerebellum, midbrain, thalamus and hypothalamus of the obese animals showed significantly higher AChE activity than their lean littermates. It was concluded from this study that obesity may be associated with changes in the enzymes of the brain cholinergic system.This work was supported by a grant from the National Aeronautics and Space Administration (NAG 2-411), a grant from the National Institutes of Health (NIH RR 0811), and a grant from the Division of Research Resources, National Institutes of Health (NIH Grant RR 03020).     

Altered brain cholinergic enzymes activity in the genetically obese rat

Genetically obese male Zucker rats (fa/fa) and their lean littermates (Fa/-) were used in this experiment. Fourteen-week-old obese and lean littermates were sacrificed and choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) enzymes were assayed in specific brain regions. The assays of these enzymes indicate that obese animals had a significantly lower ChAT activity in the cerebellum, pons, and cerebral cortex and a significant increase in ChAT activity in the thalamus and hypothalamus. Meanwhile, the cerebral cortex, cerebellum, midbrain, thalamus and hypothalamus of the obese animals showed significantly higher AChE activity than their lean littermates. It was concluded from this study that obesity may be associated with changes in the enzymes of the brain cholinergic system.     

Plasma prostaglandin levels in fed and starved lean, normal and obese women.

The plasma obtained from fed and starved lean, normal and obese women was estimated, by a radio-immunoassay method, for prostaglandins, owing to their implication in the regulation of adipose tissue lipolysis and the development of obesity. No significant differences were found due to nutritional status or body-build. However, a significantly higher plasma concentration of prostaglandins of the E-type than of the F-type, was found consistently. The very low levels of prostaglandins observed (a range of 0.10--0.15 ng ml-1 for E-type and a range of 0.05--0.07 ng ml-1 for the F-type) may be due, in part, to the activity of a plasmatic prostaglandin metabolizing system.     

Colony promoting activity and its target 'pre-CFUc' in genetically anemic mice of W/Wv genotype

Incubation of bone marrow cells with supernatant from long-term cultures of bone marrow cells increases the number of granulocyte-macrophage progenitor cells. This study reveals the presence of target cells of the colony promoting activity (CPA) in W/Wv mouse marrow. It is also shown that CPA does not stimulate erythroid colony formation in vitro.     

Mast cells in the pinna of Balb/c 'nude' (nu/nu) and heterozygotes (ny/+)mice.

The relative number of mast cells in the ear lobes' skin (pinna) of nude (athymic) nu/nu and normal (thymic) nu/+ heterozygotes of Balb/c mice was similar. The results obtained contradict some suggestions about the general influence of the thymus on the number of mast cells in the skin and suggest the existence of some local factor(s) in regulation of skin mast cell numbers.     

Mast cells in the pinna of Balb/c ‘nude’ (nu/nu) and heterozygotes (nu/+) mice

Summary The relative number of mast cells in the ear lobes' skin (pinna) of nude (athymic) nu/nu and normal (thymic) nu/+ heterozygotes of Balb/c mice was similar. The results obtained contradict some suggestions about the general influence of the thymus on the number of mast cells in the skin and suggest the existence of some local factor(s) in regulation of skin mast cell numbers.This work was supported by grant No. CA16426.The author wishes to thank Dr Kenneth Morrison for supplying the mice and the discussion, Mr Duffy Michowski for taking care of the animals used, Mr Carl Polley for taking the pictures and Dr N. R. Rose for the discussion.     

Pseudocholinesterase in obesity: Hypercaloric diet induced changes in experimental obese mice

Summary Pseudocholinesterase activity is significantly higher in liver and serum, but lower in adipose tissue of genetically obese, diabetic and gold thioglucose treated mice. Similar enzyme changes were also observed in lean mice on a high carbohydrate diet. A marked reduction (40%) in PChE activity occurred in the liver of genetically diabetic mice when starved for 24 h. These observations suggest that pseudocholinesterase induction in the liver and repression in the adipose tissue is affected by excessive calorie intake in obesity. This provides a model to study the biological function of PChE in health and disease.Acknowledgments. We thank Dr Charles A. Janeway Child Health Centre and Faculty of Medicine, Memorial University of Newfoundland for financial support.     

Dystrophic mutation (dy2J) affecting regulation of lactate dehydrogenase (LDH) and pyruvate kinase (PK) in C57BL/6J mice

Summary The genotype difference (dystrophic vs nondystrophic) in the LDH isozymes is observed in kidney. These differences are evident only at birth and at early developmental stages (before the expression of dystrophic symptoms). The tissue specific genotype differences for PK are limited to the thigh muscle (M form) and heart (L form), after the onset of the condition. These differences may reflect the pleiotropic effect of the dy^2J locus during the temporal regulation of these and other enzymes implicated in muscular dystrophy (MD).This research was financed by a Natural Sciences and Engineering Research Council Canada grant to S.M.S.     

Lipolytic response of ‘diabetic’ mice (db/db) to isoproterenol and propranolol in vivo

Summary The genetically diabetic and obesedb/db mice responded lipolytically to isoproterenol and propranolol similarly to normal mice in vivo. However, considering the large amount of triglyceride in adb/db mouse, we conclude that the in vivo response ofdb/db adipose tissue is deficient in magnitude.     

Brain catecholamines and organ weight of mice genetically selected for high and low blood pressure

Summary Statistically significant differences were found between the high and low genetically selected blood pressure lines for systolic blood pressure, norepinephrine content of whole brain, absolute heart weight, heart to b. wt ratio, kidney weight, kidney to b. wt ratio, and adrenal to b. wt ratio.This research was supported in part by an allocation from the General Research Fund of the University of Kansas and the Biomedical Sciences Support Grant RR-07037.