Regulation of new fat cell formation in rats: the role of dietary fats.

G Shillabeer,D C Lau

doi:10.1016/s0022-2275(20)41173-3

Abstract

Factors that stimulate formation of new adipocytes during development of obesity are yet to be identified. We examined whether diet acts directly on preadipocytes to stimulate replication and differentiation or indirectly by interacting with adipocytes to release or modify local growth factors. Male Sprague-Dawley rats were fed chow or diets high in starch (HST), saturated (HFS) or polyunsaturated (HFP) fats until 5-7 months of age. We found that, compared to other diets, HFS induced acceleration of replication of preadipocytes in primary culture (doubling time of retroperitoneal-derived preadipocytes: HFS 17 +/- 1 versus chow 32 +/- 6 and HFP 29 +/- 3 h, P < 0.05). HFS stimulated greater expansion of retroperitoneal fat than HFP even when caloric intake was equal and increased adipocyte number threefold. Preadipocyte pool size in inguinal and retroperitoneal fat pads changed relative to fat pad weight in rats fed all diets compared to chow, suggesting that the balance between the number of cells capable of replicating and those terminally differentiated was perturbed. Differentiation of preadipocytes and release of adipocyte growth factors in vitro were unaffected by diet. We concluded that dietary saturated fats induced expansion of adipose tissue mass more effectively than polyunsaturated fats and that this may, in part, be achieved by acceleration of preadipocyte replication.

Highlights

Factors that stimulate formation of new adipocytes during development of obesity are yet to be identified
It is well established that an increase in the number of adipocytes occurs during the development of obesity in humans [1] and in rodents (2, 3 ), factors that stimulate the formation of new adipocytes are yet to be identified
Preadipocytes derived from massively obese adult humans have been shown to replifaster in vitro than those derived from nonobese subjects [5] those derived from g-enetically obese rats did not [6]: A role for paracrine factors in the control of adipose tissue growth is suggested by the observation of regional variations in growth in vivo [2] and in vitro [7, 8]

Summary

Introduction

Factors that stimulate formation of new adipocytes during development of obesity are yet to be identified. HFS stimulated greater expansion of retroperitoneal fat than HFP even when caloric intake was equal and increased adipocyte number threefold. We concluded that dietary saturated fats induced expansion of adipose tissue mass more effectively than polyunsaturated fats and that this may, in part, be achieved by acceleration of preadipocyte replication.-Shillabeer, G., and. I n vivo, such paracrine factors, released by constituent cells of adipose tissue, may be subject to modulation by caloric intake or specific dietary components and may play a role in the expansion of adipose tissue mass in the development of obesity. Dietary fats may act directly on preadipocytes to increase the rate of replication and/or differentiation They may act by modulating the activity or release of paracrine factors, by modifying the hormonal milieu, or by affecting substrate delivery to adipose tissue. Small changes in lipogenic enzyme activity induced by dietary fats of different composition may, over the long term, have significant impact on the total lipid accumulated in adipose tissue and, on the development of obesity

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