PubMed Health⌕ Search

Biomedical subjects

G Mory

Publications and source records attributed to G Mory.

30 records · Page 2Linked to original sources
PubMed1983

Development and activation of brown fat in rats with pheochromocytoma PC 12 tumors.

To study the neurohormonal determinism of cellular growth and differentiation and mitochondrial development in brown adipose tissue (BAT), this organ was analyzed in rats bearing uncloned or cloned (PC 12) pheochromocytoma; comparison was made with cold adaptation. Both uncloned and PC 12 tumors induced an enlargement of tissue weight and DNA total content, although smaller than during cold adaptation. The following striking modifications were observed in rats bearing PC 12 tumors: strong vasodilation, increase in protein and phospholipid percentage, alteration of the fatty acid composition of phospholipids, increase in mitochondrial protein, large increase of the GDP binding to isolated mitochondria, and marked rise in specific amount of 32,000-dalton uncoupling protein (ascertained using immunological approach). It is concluded that secretions of PC 12 tumors can induce the same alterations in BAT as does the sympathetic system during cold adaptation of animals. An important contribution of norepinephrine to these effects is evidenced, but a specific function of other trophic factors secreted by PC 12 cells and by sympathetic nerves can be postulated.

Acclimatization↗
PubMed1982

Impairment of trophic response of brown fat to cold in guanethidine-treated rats.

The aim of the present study was to investigate the role of the sympathetic nervous system in the trophic response of brown adipose tissue (BAT) to chronic cold exposure. The hyperplasia and the development of the mitochondria characterizing this response are usually considered as mainly controlled by the sympathetic activity in BAT, but this has never been clearly demonstrated. In the present work rats were sympathectomized by chronic administration of guanethidine and then exposed to cold during two weeks. The treatment induced a strong reduction of the noradrenaline content of BAT. The trophic response of the tissue to cold was largely impaired: no increase of the tissue weight, weak increase in the DNA, protein, and phospholipid content of the tissue. The development of the mitochondria was almost abolished. The increase in the proportion of the 32,000-dalton protein, a protein which regulates heat production by BAT, was suppressed and the GDP-binding to mitochondria, which is an index of BAT thermogenic capacity, was not increased as in normal cold-adapted rats. The ultrastructure of the tissue remained the same as in warm-adapted animals. It is concluded that the sympathetic nervous system plays an essential role in the control of the trophic response of BAT to the cold.

Adaptation, Physiological↗
PubMed1982

Ultrastructural and biochemical characterization of human brown adipose tissue in pheochromocytoma.

The amount and distribution of brown adipose tissue (BAT) in healthy adult human subjects remain uncertain. BAT has been described in patients with pheochromocytoma. This pathological situation was chosen to try to characterize human BAT using both morphological and biochemical criteria. Typical multilocular brown adipocytes were observed; the cytoplasm of these adipocytes was filled with mitochondria with numerous tightly packed cristae, as in rat or hamster BAT. Isolated mitochondria exhibited a loose respiratory coupling sensitive to guanosine diphosphate; the chloride conductance of these mitochondria was reduced by the addition of this nucleotide. It is concluded that in patients with pheochromocytoma, there is a large amount of a tissue around the adrenal glands and kidneys which fullfills the ultrastructural and biochemical criteria for a BAT.

Adipose Tissue, Brown↗
PubMed1981

Effects of hypothyroidism on the brown adipose tissue of adult rats: comparison with the effects of adaptation to cold.

Hypothyroidism was induced in adult rats by oral absorption of methimazole and its effects on brown adipose tissue (BAT) were studied. Hypothyroidism partially mimicked the effects of chronic exposure to cold: BAT weight and its DNA content were increased and the mitochondrial components (proteins, phospholipids) of the tissue were greatly enhanced when expressed per unit of fresh tissue weight. Moreover, hypothyroidism had the same effects as adaptation to cold on the fatty-acid composition of both total and mitochondrial phospholipids. Basal respiratory rate and total cytochrome C oxidase activity of the tissue were also increased. However, the increase in the concentration of the '32,000 mol. wt protein', a polypeptide which regulates the dissipation of heat by BAT, was smaller and non-selective in hypothyroid rats. The amount of this protein was increased per mg tissue, but not per mg mitochondrial proteins, as in rats adapted to cold. Furthermore, in contrast with the large mobilization of the lipid stores in BAT of euthyroid animals, the BAT lipid stores of hypothyroid rats were not mobilized during the first hours of exposure to cold. It may be concluded that (a) hypothyroidism induces several alterations in BAT which are characteristic of an active thermogenic state (this may be because of the response of the organism to the deficiency of thermogenesis induced by hypothyroidism), (b) this potential increase in thermogenic capacity in the BAT of hypothyroid rats has probably a limited physiological role, since thyroid hormones are necessary for the mobilization of the tissue lipids which are the fuel for production of heat and (c) these data provide evidence for a limited role of thyroid hormones in the tropic response of BAT during adaptation to cold.

Adaptation, Physiological↗
PubMed1980

Effects of chronic treatments upon the brown adipose tissue of rats. II. Comparison between the effects of catecholamine injections and cold adaptation.

The role of noradrenaline in the trophic response of brown adipose tissue (BAT) to chronic and cold exposure was studied in young adult rats treated chronically with catecholamines. 2 In young rats, it was difficult to induce a BAT development with this type of treatment. After injection of a beta-agonist (isopropylnoradrenaline) directly upon BAT, a slight hypertrophy of the tissue was observed accompanied by a decrease of its relative protein content. 3 In adult rats, catecholamines were able to induce a growth of BAT and increases of the DNA and protein contents which were as great as in the BAT of cold-exposed rats. 4 Catecholamine treatments did not reproduce the effects of cold exposure on the phospholipids of BAT in either young or adult rats. 5 In the BAT of rats receiving chronically thyroxine and catecholamines, no synergy was observed. Moreover, a chronic treatment by thyroxine induced a slight increase of the DNA content of BAT in rats bred at room temperature, but prevented the marked DNA increase observed in cold-exposed animals.

Adaptation, Physiological↗
PubMed1979

Changes induced by cold adaptation in the brown adipose tissue from several species of rodents, with special reference to the mitochondrial components.

(1) The effects of cold adaptation upon the brown adipose tissue have been studied in rats, hamsters, mice, and guinea pigs. (2) Striking effects were found for total tissue as well as at the mitochondrial level, e.g., increases in protein and phospholipid contents, changes in phospholipid fatty acid composition (a decrease in the percentage of palmitic and palmitoleic acids and an increase in stearic and linoleic acids), and a change in the mitochondrial polypeptide composition (a marked increase in a 32000 molecular weight polypeptide, except for hamsters). (3) In situations where animals exhibit a greatly enhanced capacity for nonshivering thermogenesis (cold adaptation for rats, mice, and guinea pigs, birth for guinea pigs, and hibernation ability for hamsters, dormice, and garden dormice), brown fat mitochondria are characterized by the occurrence of large amounts of the 32000 molecular weight polypeptide characteristic of these mitochondria.

Adaptation, Physiological↗
PubMed1978

Effects of cold adaptation and re-adaptation upon the mitochondrial phospholipids of brown adipose tissue.

1. A study of the mitochondrial phospholipids, phospholipid fatty acid patterns and enzyme activities was investigated in brown tissue (B.A.T.) from rats chronically exposed to cold and/or treated with thyroxine. 2. The total activities of the oxidative enzymes were increased after cold exposure, but not after thyroxine treatment. 3. Cold exposure increased the amount of phosphatidylethanolamine, phosphatidylcholine, cardiolipin and lysophospholipids, the effect being greatest for phosphatidylethanolamine. At the same time, there were marked alterations in the fatty acid composition of the mitochondrial phospholipids (decrease of palmitic, palmitoleic and oleic acids ; increase of stearic, linoleic and arachidonic acids). 4. All these cold-induced alterations were reversed by re-adaptation of the animal to a normal temperature range. 5. The alterations of the fatty acid composition of phospholipids could be explained by changes in the rate of individual fatty acid biosynthesis.

Adaptation, Physiological↗
PubMed1976

Effects of chronic treatments upon the brown adipose tissue of young rats. I. Cold exposure and hyperthyroidism.

1. The gross composition, triglycerides and phospholipids of brown adipose tissue were studied in young and adult rats chronically treated with cold or thyroxine. 2. Cold induced an increase of the total water, protein and phospholipid of tissue while the main effect of thyroxine treatment was an accumulation of triglycerides. Thyroxine treatment prevented the cold-induced increase of phospholipid percentage in the tissue. 3. Cold exposure altered the fatty acid pattern of phospholipids, whereas thyroxine had smaller and different effects. 4. The differential effects of cold and hyperthyroidism upon triglycerides and phospholipids of brown adipose tissue are briefly discussed.

Adipose Tissue, Brown↗
PubMed1975

The lipoprotein lipase activity of brown adipose tissue during early post-natal development of the normal and hypothyroid rat.

The heparin-releasable LP lipase activity of BAT (brown adipose tissue), and the TG (triglyceride) content of plasma were determined in normal and hypothyroid rats during early post-natal development. The TG content of plasma increased sharply after the onset of suckling and decreased during the weaning period in normal rats, while it stayed at a high level in hypothyroid rats. LP lipase activity was maximal during the perinatal period and decreased later, being practically undetectable in one month old control animals; in contrast, LP lipase activity was still present in cretin rats at this age. The effects of several forms of treatment were also tested in weaned rats: a high-fat diet was not able to maintain the high LP lipase activity of suckling rats, but the activity was high if the animals were bred at a cold temperature. Thyroxine injections had no effect. These results are discussed in terms of the possible factors regulating the LP lipase activity in BAT.

Adipose Tissue, Brown↗