A second look at leptin and adiponectin actions on the growth of primary porcine myoblasts under serum-free conditions

Katja Will,Jan-Peter Hildebrandt,Marie-France Palin,Judith Kuzinski,Charlotte Rehfeldt

doi:10.7482/0003-9438-57-029

Abstract

Abstract. Cross-talk between adipose tissue and skeletal muscle may be mediated in part by adipokines. This study was conducted to elucidate further aspects of a possible role of recombinant adiponectin and leptin in the in vitro growth of primary porcine skeletal muscle cells cultured in energetically balanced, growth factor-supplemented, serum-free medium (GF-SFM). Therefore, the effects of these adipokines on cell number (DNA content), DNA synthesis rate, cell death and on key intracellular signalling molecules were investigated. Short-term adiponectin and leptin treatment decreased DNA synthesis, measured as [3H]-thymidine incorporation, as early as after 4-h exposure (P<0.01), without alterations in DNA content. Both adipokines attenuated the rate of cell death in terms of lactate dehydrogenase (LDH) activity in the culture medium after 48-h treatment (P<0.05). The specific activation of p44/42 MAP kinase (MAPK) was reduced (P<0.05) after 15-min incubation with either adipokine. In conclusion, the early decreases in DNA synthesis of primary porcine myoblasts cultured in GF-SFM in response to adiponectin or leptin are related to p44/42 MAPK signalling and adipokine treatment does not impair cell viability.

Highlights

Today, the view of adipose tissue as an active endocrine organ by its ability to secrete adipokines is well-established (Miner 2004, Hauner 2005, Gimeno & Klaman 2005)
In addition to findings reported in our previous study (Will et al 2012), it is shown here that short-term treatment of primary porcine skeletal muscle cells with adiponectin or leptin in growth factor-supplemented serum-free medium (GF-SFM) led to diminished DNA synthesis rate, whereas DNA content remained unaffected
We further provide evidence that p44/42 mitogen-activated protein kinase (MAPK) signalling is involved in mediating the adipokine effects, i.e. proliferation

Summary

Introduction

The view of adipose tissue as an active endocrine organ by its ability to secrete adipokines is well-established (Miner 2004, Hauner 2005, Gimeno & Klaman 2005). Concerning adipokine-mediated regulation of intracellular signalling pathways, the AMPactivated protein kinase (AMPK) was shown to be activated by globular and full-length adiponectin treatment in skeletal muscle of rats and humans (Tomas et al 2002, Tsao et al 2003, Mullen et al 2009). As adiponectin and leptin can stimulate antagonistic intracellular pathways, it is difficult to predict the effects of these adipokines on muscle cell growth. To elucidate further aspects of adiponectin and leptin action on the growth of porcine skeletal muscle cells under serum-free culture conditions in growth factor-supplemented serum-free medium (GF-SFM), the effects of these adipokines on cell number (DNA content) and DNA synthesis rate after short-term treatment as well as on cell death and the activation of key signalling molecules involved in energy metabolism and cell growth were investigated

Methods

Results

Conclusion