Innervation Of Adipose Tissue Research Articles

Nutritional regulation of lipid metabolism in human adipose tissue.

Pfeiffer and colleagues years ago pointed out that different distributions and amounts of adipose tissue are associated with abnormalities of lipolysis and lipoprotein metabolism. Adipose tissue has several crucial roles including (i) mobilization from stores of fatty acids as an energy source, (ii) catabolism of lipoproteins such as very-low-density lipoprotein and (iii) synthesis and release of hormonal signals such as leptin and interleukin-6. These adipose tissue actions are crucially regulated by nutrition. The review considers the existence of metabolic pathways and modes of regulation within adipose tissue, and how such metabolic activity can be quantitated in humans. Nutrition can influence adipose tissue at several 'levels'. Firstly the level of obesity or malnutrition has important effects on many aspects of adipose tissue metabolism. Secondly short-term overfeeding, underfeeding and exercise have major impacts on adipose tissue behaviour. Lastly, specific nutrients are capable of regulating adipose tissue metabolism. Recently there have been considerable advances in understanding adipose tissue metabolism and in particular its regulation. This review discusses the behaviour of adipose tissue under various nutritional conditions. There is then a review of recent work examining the ways in which nutritional influences act via intra-cellular mechanisms, insulin and the sympathetic innervation of adipose tissue.

Adrenergic innervation of fetal pig adipose tissue. Histochemical and ultrastructural studies.

Histochemistry and electron microscopy were used to study the adrenergic innervation of subcutaneous adipose tissue in fetal pigs. Adrenergic innervation was present around arteries, arterioles, and adipocyte-associated capillaries. Nerve fibers were infrequently observed around veins, venules, and adipocytes. Ultrastructural features of nerves included mitochondria, clear synaptic vesicles, and a small number of vesicles with a core of electron-dense material. Innervation of adipose tissue was similar in 70-, 90-, and 110-day-old fetuses. Examination of fetuses decapitated at 45 days of gestation and removed at 110 days showed that adrenergic innervation was absent in adipose tissue of decapitated fetuses. Adrenergic innervation was also absent in adipose tissue from fetuses hypophysectomized at 72-73 days of gestation and examined at 110 days. These data indicate that fetal porcine adipose tissue may be under neural control by day 70 of gestation. Furthermore, an intact pituitary is necessary for the development of adrenergic innervation in fetal adipose tissue.

Control of brown fat thermogenesis by the sympathetic nervous system.

Brown adipose tissue innervation as well as the effects of denervation and nerve stimulation on the metabolic activity of this tissue are briefly discussed. Direct control of the metabolic activity of brown adipocytes by sympathetic nerves was studied. Electrical stimulation was found to mimick the effects of norepinephrine on the adipocytes, i.e., it caused an increase in both NAD(P)H production and oxygen consumption of the tissue and a depolarization of the cytomembrane. These effects were graded as a function of stimulation frequency. The temporal relationship of the responses was determined and it was found that depolarization started first, was followed by pyridine nucleotide reduction and finally by an increase in respiration.

Control of brown fat thermogenesis by the sympathetic nervous system.

Brown adipose tissue innervation as well as the effects of denervation and nerve stimulation on the metabolic activity of this tissue are briefly discussed. Direct control of the metabolic activity of brown adipocytes by sympathetic nerves was studied. Electrical stimulation was found to mimick the effects of norepinephrine on the adipocytes, i.e., it caused an increase in both NAD(P)H production and oxygen consumption of the tissue and a depolarization of the cytomembrane. These effects were graded as a function of stimulation frequency. The temporal relationship of the responses was determined and it was found that depolarization started first, was followed by pyridine nucleotide reduction and finally by an increase in respiration.

Effects of denervation and fasting on white adipose tissue.

Effects of denervation and fasting on white adipose tissue.

Adrenergic innervation of adipose tissue in vertebrates: By V. A. Govyrin and D. I. Popova: Institute of Evolutionary Physiology and Biochemistry of the Academy of Sciences of the USSR, Leningrad, pp. 337–342

Adrenergic innervation of adipose tissue in vertebrates: By V. A. Govyrin and D. I. Popova: Institute of Evolutionary Physiology and Biochemistry of the Academy of Sciences of the USSR, Leningrad, pp. 337–342

Metabolism of free fatty acids during perinatal life of lambs

1.1. Studies of the mechanisms responsible for the rapid rise in the concentration of free fatty acids (FFA) in blood plasma after birth were done in newborn lambs.2.2. From changes in the specific radioactivity of free fatty acids of plasma during constant intravenous infusion of palmitate 1-C14 it was shown that the increase in plasma concentration of FFA after birth is the result of augmented mobilization of free fatty acids into the blood. This mobilization was reversed by blocking transmission at autonomic ganglia with hexamethonium.3.3. Intravenous injection of approximately 50 μg norepinephrine per kilogram body weight was required to increase FFA in blood plasma of newborn lambs; 2 μg per kilogram body weight was effective in ewes.4.4. Sensitivity to the effect of norepinephrine was not increased by fasting newborn lambs up to 40 hours, and increased sensitivity could not be demonstrated until the lambs were 8 weeks old.5.5. The results are compatible with the concept that increased activity of sympathetic nerves innervating adipose tissue is an important factor in the rapid mobilization of FFA into the blood after birth, and suggest that secretion of norepinephrine from the adrenal medulla is not involved.

Adrenergic Innervation of Adipose Tissue examined by Fluorescence Microscopy

EVIDENCE of a sympathetic nerve supply to the fat cells in adipose tissue has been based on histological observations of material stained with silver or methylene blue1,2 and on biochemical analysis of the noradrenaline content3,4. Further, an increased production of free fatty acids from adipose tissue after nerve stimulation has been reported5, as have the inhibitory effects on this production resulting from denervation5 or treatment with reserpine3. The concept of a direct innervation of fat cells seems also to be consistent with the fact that noradrenaline has an adipokinetic effect both in vivo and in vitro, although certain species are apparently unresponsive6,7. With the fluorescence method described by Falck et al.8, Carlsson, Falck and Hillarp9 and Falck10, noradrenaline can be demonstrated with very good resolution even in small nerve fibres, and it may now be possible to make more adequate observations of their distribution in adipose tissue.