Lipolysis is a highly regulated process and is controlled by nervous system, hormones, and paracrine/autocrine factors. Dysregulation of lipolysis is associated with some pathophysiological conditions including diabetes, metabolic syndrome, and obesity. Nowadays, special attention isthereforepaid to study lipolysis using different experimental models. This review summarizes the current experimental methods for studying lipolysis. Culture of preadipocyte cell lines, use of differentiated stroma-vascular cells, primary culture of adipocyte, organ culture of adipose tissue, and microdialysis technique are the most widely used techniques to study lipolysis. The advantages and limitations of using these methods are discussed. 1. Introduction Adipose tissue is one of the largest body compartments with various physiological roles including lipid handling and hormone secretion. It is responsible for the storage of fat as triglyceride (via lipogenesis) during times of energy excess and for the mobilization of triglyceride (via lipolysis) during periods of calories deficit [1]. Hormone-sensitive lipase, a rate-limiting enzyme, and monoglyceride lipase catalyse hydrolysis of triglyceride to release fatty acids and glycerol. Unlike fatty acids, glycerol is not reutilized by adipocytes because these cells contain very little glycerol kinase [2]. Therefore, measurement of glycerol gives a good estimate for level of lipolysis [3]. Lipolysis is a highly regulated process and is disciplined by nervous system, hormones (e.g., insulin and catecholamines), and paracrine/autocrine factors (e.g., adenosine, prostaglandins, nitric oxide, and TNF-α) [1, 3–5]. Physical activity, nutrition, gender, age and genetic are also important determinant factors for lipolysis [2, 4]. Dysregulation of lipolysis is associated with a number of pathophysiological conditions such as obesity, diabetes, metabolic syndrome, familial combined hyperlipidaemia, and polycystic ovarian syndrome [4]. Nowadays, special attention is therefore paid to study lipolysis and other aspects of adipose tissue metabolism. While isotopic tracer techniques and arteriovenous difference method allow in vivo estimation of lipolysis, culture of preadipocyte cell lines, primary culture of adipocyte, organ culture of adipose tissue, and microdialysis are of the most used techniques for studying lipolysis in vitro and in situ. This review summarizes the in vitro and in situ techniques for studying lipolysis in animal and humans. Moreover, the advantages and drawbacks of using each method are discussed (Table 1). Table 1:
References
[1]
M. Ahmadian, Y. Wang, and H. S. Sul, “Lipolysis in adipocytes,” International Journal of Biochemistry and Cell Biology, vol. 42, no. 5, pp. 555–559, 2010.
[2]
V. Large, O. Peroni, D. Letexier, H. Ray, and M. Beylot, “Metabolism of lipids in human white adipocyte,” Diabetes and Metabolism, vol. 30, no. 4, pp. 294–309, 2004.
[3]
S. Viswandha and C. Londos, “Determination of lipolysis in isolated primary adipocytes,” in Adipose Tissue Protocols, K. Yang, Ed., pp. 299–306, Humana Press, Totowa, NJ, USA, 2nd edition, 2008.
[4]
P. Arner, “Human fat cell lipolysis: biochemistry, regulation and clinical role,” Best Practice and Research, vol. 19, no. 4, pp. 471–482, 2005.
[5]
G.-Y. Carmen and S.-M. Víctor, “Signalling mechanisms regulating lipolysis,” Cellular Signalling, vol. 18, no. 4, pp. 401–408, 2006.
[6]
H. Green and O. Kehinde, “An established preadipose cell line and its differentiation in culture. II. Factors affecting the adipose conversion,” Cell, vol. 5, no. 1, pp. 19–27, 1975.
[7]
E. R. Hugo, T. D. Brandebourg, C. E. S. Comstock, K. S. Gersin, J. J. Sussman, and N. Ben-Jonathan, “LS14: a novel human adipocyte cell line that produces prolactin,” Endocrinology, vol. 147, no. 1, pp. 306–313, 2006.
[8]
M. Wabitsch, S. Bruderlein, I. Melzner, M. Braun, G. Mechtersheimer, and P. Moller, “LiSa-2, a novel human liposarcoma cell line with a high capacity for terminal adipose differentiation,” International Journal of Cancer, vol. 88, pp. 889–894, 2000.
[9]
I. Torii, S. Morikawa, A. Nakano, and K. Morikawa, “Establishment of a human preadipose cell line, HPB-AML-I: refractory to PPARγ-mediated adipogenic stimulation,” Journal of Cellular Physiology, vol. 197, no. 1, pp. 42–52, 2003.
[10]
R. Li, H. Guan, and K. Yang, “Neuropeptide Y potentiates beta-adrenergic stimulation of lipolysis in 3T3-L1 adipocytes,” Regulatory Peptides, vol. 178, pp. 16–20, 2012.
[11]
L. Zhou, X. Wang, Y. Yang et al., “Berberine attenuates cAMP-induced lipolysis via reducing the inhibition of phosphodiesterase in 3T3-L1 adipocytes,” Biochimica et Biophysica Acta, vol. 1812, no. 4, pp. 527–535, 2011.
[12]
X. Guo and K. Liao, “Analysis of gene expression profile during 3T3-L1 preadipocyte differentiation,” Gene, vol. 251, no. 1, pp. 45–53, 2000.
[13]
S. P. Poulos, M. V. Dodson, and G. J. Hausman, “Cell line models for differentiation: preadipocytes and adipocytes,” Experimental Biology and Medicine, vol. 235, no. 10, pp. 1185–1193, 2010.
[14]
D. C. Adler-Wailes, E. L. Guiney, N. E. Wolins, and J. A. Yanovski, “Long-term ritonavir exposure increases fatty acid and glycerol recycling in 3T3-L1 adipocytes as compensatory mechanisms for increased triacylglycerol hydrolysis,” Endocrinology, vol. 151, no. 5, pp. 2097–2105, 2010.
[15]
G. Fruhbeck, “Overview of adipose tissue and its role in obesity and metabolic disorders,” in Adipose Tissue Protocols, K. Yang, Ed., pp. 1–22, Humana Press, Totowa, NJ, USA, 2nd edition, 2008.
[16]
A. Ghorbani, M. R. Hadjzadeh, Z. Rajaei, and S. B. Zendehbad, “Effects of fenugreek seeds on adipogenesis and lipolysis in normal and diabetic rats,” Pakistan Journal of Biological Sciences. In press.
[17]
M. Rodbell, “Metabolism of isolated fat cells: effects of hormones on glucose metabolism and lipolysis,” The Journal of Biological Chemistry, vol. 239, pp. 375–380, 1964.
[18]
J. R. Monzon, R. Basile, S. Heneghan, V. Udupi, and A. Green, “Lipolysis in adipocytes isolated from deep and superficial subcutaneous adipose tissue,” Obesity Research, vol. 10, no. 4, pp. 266–269, 2002.
[19]
S. K. Fried and N. Moustaid-Moussa, “Culture of adipose tissue and isolated adipocytes,” Methods in Molecular Biology, vol. 155, pp. 197–212, 2001.
[20]
R. Taylor, “Use of adipose tissue for metabolic studies,” Bailliere's Clinical Endocrinology and Metabolism, vol. 1, no. 4, pp. 1023–1035, 1987.
[21]
R. C. Honnor, G. S. Dhillon, and C. Londos, “cAMP-dependent protein kinase and lipolysis in rat adipocytes. I. Cell preparation, manipulation, and predictability in behavior,” Journal of Biological Chemistry, vol. 260, no. 28, pp. 15122–15129, 1985.
[22]
K. A. Carswell, M.-J. Lee, and S. K. Fried, “Culture of isolated human adipocytes and Isolated adipose tissue,” Methods in Molecular Biology, vol. 806, pp. 203–214, 2012.
[23]
P. M. Gerrits, A. L. Olson, and J. E. Pessin, “Regulation of the GLUT4/muscle-fat glucose transporter mRNA in adipose tissue of insulin-deficient diabetic rats,” Journal of Biological Chemistry, vol. 268, no. 1, pp. 640–644, 1993.
[24]
C. T. Montague, J. B. Prins, L. Sanders, J. E. Digby, and S. O'Rahilly, “Depot- and sex-specific differences in human leptin mRNA expression: implications for the control of regional fat distribution,” Diabetes, vol. 46, no. 3, pp. 342–347, 1997.
[25]
P. Arner, “Differences in lipolysis between human subcutaneous and omental adipose tissues,” Annals of Medicine, vol. 27, no. 4, pp. 435–438, 1995.
[26]
M. Stolic, A. Russell, L. Hutley et al., “Glucose uptake and insulin action in human adipose tissue—influence of BMI, anatomical depot and body fat distribution,” International Journal of Obesity, vol. 26, no. 1, pp. 17–23, 2002.
[27]
A. Ghorbani, M. Varedi, and G. R. Omrani, “Effects of aging associated weight gain on the cell size and heterogeneity of different fat depots in the rat,” Iranian Journal of Endocrinology & Metabolism, vol. 11, pp. 713–720, 2009.
[28]
A. Ghorbani, M. Varedi, M.-A.-R. Hadjzadeh, and G. H. Omrani, “Type-1 diabetes induces depot-specific alterations in adipocyte diameter and mass of adipose tissues in the rat,” Experimental and Clinical Endocrinology and Diabetes, vol. 118, no. 7, pp. 442–448, 2010.
[29]
B. Richelsen, S. B. Pedersen, T. Moller-Pedersen, and J. F. Bak, “Regional differences in triglyceride breakdown in human adipose tissue: effects of catecholamines, insulin, and prostaglandin E2,” Metabolism, vol. 40, no. 9, pp. 990–996, 1991.
[30]
J. R. Zierath, J. N. Livingston, A. Th？rne et al., “Regional difference in insulin inhibition of non-esterified fatty acid release from human adipocytes: relation to insulin receptor phosphorylation and intracellular signalling through the insulin receptor substrate-1 pathway,” Diabetologia, vol. 41, no. 11, pp. 1343–1354, 1998.
[31]
G. Tavernier, J. Galitzky, P. Valet et al., “Molecular mechanisms underlying regional variations of catecholamine- induced lipolysis in rat adipocytes,” American Journal of Physiology. Endocrinology and Metabolism, vol. 268, no. 6, pp. E1135–E1142, 1995.
[32]
B. G. Slavin and J. J. Elias, “The influence of pituitary hormones and norepinephrine on the size of adipose cells in organ culture,” Anatomical Record, vol. 164, no. 2, pp. 141–151, 1969.
[33]
A. Ghorbani, G. R. Omrani, M. A. R. Hadjzadeh, and M. Varedi, “Effects of rat C-peptide-II on lipolysis and glucose consumption in cultured rat adipose tissue,” Experimental and Clinical Endocrinology and Diabetes, vol. 119, no. 6, pp. 343–347, 2011.
[34]
A. Ghorbani, G. H. Omrani, M. R. Hadjzadeh, and M. Varedi, “Proinsulin C-peptide inhibits lipolysis in diabetic rat adipose tissue through phosphodiestrase-3B enzyme,” Hormone and Metabolic Research, vol. 45, pp. 221–225, 2013.
[35]
B. Alinejad, R. Shafiee-Nick, and A. Ghorbani, “The effect of cilostamide derivatives on lipolysis of rat retroperitoneal adipose tissue,” Clinical Biochemistry, vol. 44, p. S248, 2011.
[36]
S. Gesta, K. Lolmède, D. Daviaud et al., “Culture of human adipose tissue explants leads to profound alteration of adipocyte gene expression,” Hormone and Metabolic Research, vol. 35, no. 3, pp. 158–163, 2003.
[37]
U. Smith and B. Jacobsson, “Studies of human adipose tissue in culture. II. Effects of insulin and of medium glucose on lipolysis and cell size,” Anatomical Record, vol. 176, no. 2, pp. 181–183, 1973.
[38]
R. G. Vernon, R. A. Clegg, and D. J. Flint, “Metabolism of sheep adipose tissue during pregnancy and lactation. Adaptation and regulation,” Biochemical Journal, vol. 200, no. 2, pp. 307–314, 1981.
[39]
J. P. Robertson, A. Faulkner, and R. G. Vernon, “Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue,” Biochemical Journal, vol. 206, no. 3, pp. 577–586, 1982.
[40]
M. Cifuentes, C. Albala, and C. V. Rojas, “Differences in lipogenesis and lipolysis in obese and non-obese adult human adipocytes,” Biological Research, vol. 41, no. 2, pp. 197–204, 2008.
[41]
D. Newby, A. Gertler, and R. G. Vernon, “Effects of recombinant ovine leptin on in vitro lipolysis and lipogenesis in subcutaneous adipose tissue from lactating and nonlactating sheep,” Journal of Animal Science, vol. 79, no. 2, pp. 445–452, 2001.
[42]
M. Ottosson, P. L？nnroth, P. Bj？rntorp, and S. Edèn, “Effects of cortisol and growth hormone on lipolysis in human adipose tissue,” Journal of Clinical Endocrinology and Metabolism, vol. 85, no. 2, pp. 799–803, 2000.
[43]
Y. Wang, S. K. Fried, R. N. Petersen, and P. A. Schoknecht, “Somatotropin regulates adipose tissue metabolism in neonatal swine,” Journal of Nutrition, vol. 129, no. 1, pp. 139–145, 1999.
[44]
P. Arner and J. Bolinder, “Microdialysis of adipose tissue,” Journal of Internal Medicine, vol. 230, no. 4, pp. 381–386, 1991.
[45]
P. Barbe, C. Darimont, P. Saint-Marc, and J. Galitzky, “Measurements of white adipose tissue metabolism by microdialysis technique,” Methods in Molecular Biology, vol. 155, pp. 305–321, 2001.
[46]
K. N. Frayn, B. A. Fielding, and L. K. M. Summers, “Investigation of human adipose tissue metabolism in vivo,” Journal of Endocrinology, vol. 155, no. 2, pp. 187–189, 1997.
[47]
T. Zornoza, M. J. Cano-Cebrian, A. Polache, and L. Granero, “Quantitative in vivo microdialysis in pharmacokinetic studies,” Microdialysis Techniques in Neuroscience, vol. 75, pp. 103–120, 2013.
