To the Editor: Leptin, a newly defined protein mainly synthesized by fat cells, acts as an important regulator of body weight.
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In general, circulating leptin concentration is positively correlated with adiposity. Plasma leptin levels are markedly reduced by biliopancreatic diversion and become dissociated with levels of adiposity in obese patients.2
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To our knowledge, however, the effect of the direct removal of subcutaneous fat tissues on leptinemia in human subjects has not yet been studied. Suction lipectomy is known as an effective and safe cosmetic operation to remove peripheral fat deposits and is proposed to be therapeutic for weight reduction.4
We thus performed a preliminary study to determine changes in leptinemia in women undergoing suction lipectomy.Patients and Methods.—Women who underwent suction lipectomy of abdominal subcutaneous fat deposits for weight reduction were recruited. Participants with renal or liver dysfunction, diabetes mellitus, or active infection were excluded. A total of 4 women were included in this study. Age, body mass index (BMI), and waist/hip ratio were 47, 40, 32, and 31 years; 23.6, 31.0, 26.3, and 42.7 kg/m2; and 0.83, 0.76, 0.74, and 0.85 for cases 1 through 4, respectively. Standard, machine-driven liposuction techniques with a medium-volume anesthetic wetting solution were used,
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and throughout the study period, the suction lipectomy procedure was performed by one of us (L.F.O.). Fasting blood samples were collected 1 day before (baseline) and at 1, 2, and 14 days after liposuction. Plasma concentrations of glucose, insulin, and leptin were determined as previously described.6
Results.—For all 4 patients, plasma leptin concentration correlated well with BMI (r=0.96; P=.01), waist (r=0.99; P=.005), and hip (r=0.97; P=.02) at baseline. However, the plasma leptin level did not correlate with the waist/hip ratio in this study (r=0.35; P=.38). This discrepant result might be caused by the altered distribution of body fat deposit, as in case 1, who had a higher waist/hip ratio than expected. In addition, we found that plasma leptin levels tended to decrease 30 minutes after the administration of a 75-g oral glucose challenge (–12%, –18%, and –24% in cases 1–3, respectively), whereas this effect did not occur in case 4. Nevertheless, in all participants, plasma leptin values reached the nadir (–19%, –26%, –25%, and –40% in cases 1–4, respectively) at the end (120 minutes) of the oral glucose tolerance test. Plasma leptin levels were markedly decreased on postoperative day 1, and this effect persisted to postoperative day 14 (Table 1).
Table 1Plasma Leptin Concentrations (ng/mL) of 4 Women After Suction Lipectomy
| Case 1 | Case 2 | Case 3 | Case 4 | |
|---|---|---|---|---|
| Aspirated fat (mL) | 1250 | 5540 | 2300 | 12,780 |
| Preoperation | 11.35 | 22.46 | 10.01 | 44.64 |
| Postoperative day 1 | 9.97 | 16.25 | 8.76 | 33.40 |
| Postoperative day 2 | 9.06 | 14.81 | 7.57 | 29.87 |
| Postoperative day 14 | 6.68 | 9.36 | 5.83 | 26.49 |
Discussion.—Although the reason for the reduction of leptinemia after the oral glucose challenge is still elusive, a transient suppression of leptin production during the performance of a hypoglycemic-hyperinsulinemic clamp in healthy men has been noted.
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Insulin is a potent stimulant of leptin secretion.8
However, insulin has recently been found to acutely suppress rather than stimulate leptin production.9
The occurrence of an acutely inhibitory effect of insulin on leptin production may be caused by an instinctive adaptation to maximize energy deposit when nutrients are available and to delay the satiety response until fat tissues accumulate enough energy.9
Table 1 indicates that plasma leptin levels markedly decreased, and the decrease lasted for at least 14 days after suction lipectomy. The data also showed that plasma leptin concentration acutely reflected (24 hours after liposuction) the changes in the amount of body fat deposits. In addition, plasma leptin values after suction lipectomy could be roughly predicted from the aspirated volume of fat: postoperative plasma leptin level (ng/mL) = the value of preoperative plasma leptin – (aspirated fat [mL] × 0.001). Furthermore, the plasma leptin level and BMI also became disassociated as expected. The occurrence of relative hypoleptinemia is believed to prompt hyperphagia and accompany the body weight recovery that frequently occurs in individuals after weight reduction. Accordingly, exogenous leptin administration can markedly reduce adiposity,
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and it seems that leptin repletion may protect against lipectomy-induced hypoleptinemia and its accompanying weight regain.The results of this study might be practical for individuals who receive suction lipectomy for weight reduction to monitor their postoperative circulating leptin levels as a predictor for further therapeutic modality, such as consideration of an optimal dose of exogenous leptin. Nevertheless, these suggestions remain to be elucidated by further studies of larger study groups.
REFERENCES
- The role of leptin in human obesity and diseases: a review of current evidence.Ann Intern Med. 1999; 130: 671-680
- Plasma leptin levels after biliopancreatic diversion: dissociation with body mass index.J Clin Endocrinol Metab. 1999; 84: 2386-2389
- Serum leptin and weight loss in severely obese patients undergoing biliopancreatic diversion.Int J Obes Relat Metab Disord. 1998; 22: 822-824
- Suction lipectomy.Acta Chir Plast. 1999; 41: 50-53
- The impact of liposuction on body fat.Plast Reconstr Surg. 1998; 102: 1686-1689
- Zinc may be a mediator of leptin production in humans.Life Sci. 2000; 66: 2143-2149
- Effects of hyperinsulinaemia and hypoglycaemia on circulating leptin levels in healthy lean males.Diabetes Metab. 1997; 23: 80-83
- Physiological insulinemia acutely modulates plasma leptin.Diabetes. 1998; 47: 544-549
- Dual effect of insulin on in vitro leptin secretion by adipose tissue.Biochem Biophys Res Commun. 2000; 276: 477-482
- Recombinant leptin for weight loss in obese and lean adults: a randomized, controlled, dose-escalation trial.JAMA. 1999; 282: 1568-1575
Article Info
Footnotes
This work was supported by grant TCVGH-895201C from Taichung Veterans General Hospital.
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Copyright
© 2001 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.
