Short-term Fasting and Lipolytic Activity in Rat Adipocytes

Abstract

The aim of this experiment was to study the influence of 18-hour food deprivation on basal and stimulated lipolysis in adipocytes obtained from young male Wistar rats. Fat cells from fed and fasted rats were isolated from the epididymal adipose tissue by collagenase digestion. Adipocytes were incubated in Krebs-Ringer buffer (pH 7.4, 37 °C) without agents affecting lipolysis and with different lipolytic stimulators (epinephrine, forskolin, dibutyryl-cAMP, theophylline, DPCPX, amrinone) or inhibitors (PIA, H-89, insulin). After 60 min of incubation, glycerol and, in some cases, also fatty acids released from adipocytes to the incubation medium were determined. Basal lipolysis was substantially potentiated in cells of fasted rats in comparison to adipocytes isolated from fed animals. The inhibition of protein kinase A activity by H-89 partially suppressed lipolysis in both groups of adipocytes, but did not eliminate this difference. The agonist of adenosine A₁ receptor also did not suppress fasting-enhanced basal lipolysis. The epinephrine-induced triglyceride breakdown was also enhanced by fasting. Similarly, the direct activation of adenylyl cyclase by forskolin or protein kinase A by dibutyryl-cAMP resulted in a higher lipolytic response in cells derived from fasted animals. These results indicate that the fasting-induced rise in lipolysis results predominantly from changes in the lipolytic cascade downstream from protein kinase A. The antagonism of the adenosine A₁ receptor and the inhibition of cAMP phosphodiesterase also induced lipolysis, which was potentiated by food deprivation. Moreover, the rise in basal and epinephrine-stimulated lipolysis in adipocytes of fasted rats was shown to be associated with a diminished non-esterified fatty acids/glycerol molar ratio. This effect was presumably due to increased re-esterification of triglyceride-derived fatty acids in cells of fasted rats. Comparing fed and fasted rats for the antilipolytic effect of insulin in adipocytes revealed that short-term food deprivation resulted in a substantial deterioration of the ability of insulin to suppress epinephrine-induced lipolysis.

Adipocytes · Lipolysis · Fasting

References

• 1 Kandulska K, Szkudelski T. The effect of diet on fat cell metabolism. A review.  J Anim Feed Sci. 1998;  7 233-248
• 2 Dugail I, Le Lay S, Varret M, Le Liepvre X, Dagher G, Ferré P. New insights into how adipocytes sense their triglyceride stores.  Is cholesterol a signal? Horm Metab Res. 2003;  35 204-210
• 3 Lee J J, Smith P J, Fried S K. Mechanisms of decreased lipoprotein lipase activity in adipocytes of starved rats depend on duration of starvation.  J Nutr. 1998;  128 940-946
• 4 Timmers K, Knittle J L. Effects of undernutrition and refeeding on enzyme activities and rates of glucose catabolism in rat epididymal adipose tissue.  J Nutr. 1980;  110 1176-1184
• 5 Casanova L, Alonso G, Moreno F J. Some aspects of metabolic adaptations in lipid metabolism during starvation are mimicked by epinephrine in rat adipocytes.  Int J Biochem. 1990;  22 19-23
• 6 Ben Cheikh R, Loireau A, Chomard P, Dumas P, Autissier N. Prolonged fasting on the lipolytic activity of isolated adipocytes of the rat epididymis.  C R Seances Soc Biol Fil. 1989;  183 232-239
• 7 Ben Cheikh R, Chomard P, Dumas P, Autissier N. Influence of prolonged fasting on thyroid hormone modulation of lipolysis in isolated epididymal adipocytes of Wistar rats.  Eur J Endocrinology. 1994;  131 516-521
• 8 Morimoto C, Tsujita T, Okuda H. Antilipolytic actions of insulin on basal and hormone-induced lipolysis in rat adipocytes.  J Lipid Res. 1998;  39 957-962
• 9 Chohan P, Carpenter C, Saggerson E D. Changes in the anti-lipolytic action and binding to plasma membranes of N6-L-phenylisopropyladenosine in adipocytes from starved and hypothyroid rats.  Biochem J. 1984;  223 53-59
• 10 Honnor R C, Saggerson E D. Altered lipolytic response to glucagon and adenosine deaminase in adipocytes from starved rats.  Biochem J. 1980;  188 757-761
• 11 Lacasa D, Agli B, Giudicelli Y. Increased sensitivity of fat cell adenylate cyclase to stimulatory agonists during fasting is not related to impaired inhibitory coupling system.  FEBS Lett. 1986;  202 260-266
• 12 Bertile F, Criscuolo F, Oudart H, Le Maho Y, Raclot T. Differences in the expression of lipolytic-related genes in rat white adipose tissues.  Biochem Biophys Res Commun. 2003;  307 540-546
• 13 Szkudelski T, Szkudelska K. Glucose as a lipolytic agent: Studies on isolated rat adipocytes.  Physiol Res. 2000;  49 213-217
• 14 Fried S K, Hill J O, Nickel M, DiGirolamo M. Prolonged effects of fasting-refeeding on rat adipose tissue lipoprotein lipase activity: influence of caloric restriction during refeeding.  J Nutr. 1983;  113 1861-1869
• 15 Duncombe D. The colorimetric micro-determination of nonesterified fatty acids in plasma.  Clin Chim Acta. 1964;  9 122-125
• 16 Foster L B, Dunn R T. Stable reagents for determination of serum triglycerides by colorimetric Hatzsh condensation method.  Clin Chem. 1973;  19 338-340
• 17 Rodbell M. Metabolism of isolated fat cells.  J Biol Chem. 1964;  239 375-380
• 18 Szkudelska K, Nogowski L, Szkudelski T. Genistein affects lipogenesis and lipolysis in isolated rat adipocytes.  J Steroid Biochem Mol Biol. 2000;  75 265-271
• 19 Londons C, Brasaemle D L, Schulz C J, Adler-Wailes D C, Levin D M, Kimmel A R, Rondinone C M. On the control of lipolysis in adipocytes.  Ann NY Accad Sci. 1999;  892 155-168
• 20 El Hadri K, Charon C, Pairault J, Hauguel-de Mouzon S, Quignard-Boulange A, Feve B. Down-regulation of β₃-adrenergic receptor expression in rat adipose tissue during the fasted/fed transition: evidence for a role of insulin.  Biochem J. 1997;  323 359-364
• 21 Litosch I, Hudson T H, Mills I, Li S Y, Fain J N. Forskolin as an activator of cyclic AMP accumulation and lipolysis in rat adipocytes.  Mol Pharmacol. 1982;  22 109-115
• 22 Okuda H, Morimoto C, Tsujita T. Relationship between cyclic AMP production and lisolysis induced by forskolin in rat fat cells.  J Lipid Res. 1992;  33 225-231
• 23 Liang H X, Belardinelli L, Ozeck M J, Shryock J C. Tonic activity of the rat adipocyte A1-adenosine receptor.  Br J Pharmacol. 2002;  135 1457-1466
• 24 Kather H, Scheurer A. Effects of different phosphodiesterase inhibitors on the antilipolytic action of insulin in human adipocytes.  Horm Metab Res. 1987;  19 379-381
• 25 Raclot T, Oudart H. Net release of individual fatty acids from white adipose tissue during lipolysis in vitro: evidence for selective fatty acid re-uptake.  Biochem J. 2000;  348 129-136
• 26 Wang T, Zang Y, Ling W, Corkey B E, Guo W. Metabolic partitioning of endogenous fatty acid in adipocytes.  Obes Res. 2003;  11 880-887
• 27 Reshef L, Hanson R W, Ballard F J. A possible physiological role for glyceroneogenesis in rat adipose tissue.  J Biol Chem. 1970;  245 5979-5984
• 28 Reshef L, Olswang Y, Cassuto H, Blum B, Croniger C M, Kalhan S C, Tilghman S M, Hanson R W. Glyceroneogenesis and the triglycerides/fatty acid cycle.  J Biol Chem. 2003;  278 30413-30416
• 29 Eriksson H, Ridderstråle M, Degerman E, Ekholm D, Smith C J, Manganiello V C, Belfrage P, Tornqvist H. Evidence for the key role of the adipocyte cGMP-inhibited cAMP phosphodiesterase in the antilipolytic action of insulin.  Biochim Biophys Acta. 1995;  1266 101-107
• 30 Engfeldt P, Hellmer J, Wahrenberg H, Arner P. Effect of insulin on adrenoceptor binding and the rate of catecholamine-induced liopolysis in isolated human fat cells.  J Biol Chem. 1988;  263 15553-15560
• 31 Kasuga M, Akanuma Y, Iwamoto Y, Kosaka K. Effects of fasting and refeeding of insulin receptors and glucose metabolism in rat adipocytes.  Endocrinology. 1977;  100 1384-1390
• 32 Koopmans S J, Sips H C, Bosman J, Radder J K, Krans H M. Antilipolytic action of insulin in adipocytes from starved and diabetic rats during adenosine-controlled incubations.  Endocrinology. 1989;  125 3044-3050
• 33 Páez-Espinoza E V, Rocha E M, Velloso L A, Boschero A C, Saad M JA. Insulin-induced tyrosine phosphorylation of Shc in liver, muscle and adipose tissue of insulin resistant rats.  Mol Cell Endocrinol. 1999;  156 121-129
• 34 Jimenez M, Léger B, Canola K, Lehr L, Arboit P, Seydoux J, Russell A P, Giacobino J P, Muzzin P, Preitner F. β₁/β₂/β₃-adrenoceptor knockout mice are obese and cold-sensitive but have normal lipolytic responses to fasting.  FEBS Lett. 2002;  530 37-40
• 35 Morimoto C, Kameda K, Tsujita T, Okuda H. Relationships between lipolysis induced by various lipolytic agents and hormone-sensitive lipase in rat fat cells.  J Lipid Res. 2001;  42 120-127
• 36 Egan J J, Greenberg A S, Chang M-K, Wek S A, Moos M C, Londos C. Mechanism of hormone-stimulated lipolysis in adipocytes: translocation of hormone-sensitive lipase to the lipid storage droplet.  Proc Natl Acad Sci. 1992;  89 8537-8541
• 37 Clifford G M, Londos C, Kraemer F B, Vernon R G, Yeaman S J. Translocation of hormone-sensitive lipase and perilipin upon lipolytic stimulation of rat adipocytes.  J Biol Chem. 2000;  275 5011-5015
• 38 Sztalryd C, Kraemer F B. Regulation of hormone-sensitive lipase during fasting.  Am J Physiol. 1994;  266 179-185