Sex differences in hormone-sensitive lipase expression, activity, and phosphorylation in skeletal muscle at rest and during exercise.
Women have been shown to use more intramuscular triacylglycerol (IMTG) during exercise than men. To investigate whether this could be due to sex-specific regulation of hormone-sensitive lipase (HSL) and to use sex comparison as a model to gain further insight into HSL regulation, nine women and eight men performed bicycle exercise (90 min, 60% Vo(2peak)), and skeletal muscle HSL expression, phosphorylation, and activity were determined. Supporting previous findings, basal IMTG content (P < 0.001) and net IMTG decrease during exercise (P < 0.01) were higher in women than in men and correlated significantly (r = 0.72, P = 0.001). Muscle HSL mRNA (80%, P = 0.11) and protein content (50%, P < 0.05) were higher in women than in men. HSL total activity increased during exercise (47%, P < 0.05) but did not differ between sexes. Accordingly, HSL specific activity (HSL activity per HSL protein content) increased during exercise (62%, P < 0.05) and was generally higher in men than in women (82%, P < 0.05). A similar pattern was observed for HSL Ser(659) phosphorylation, suggesting a role in regulation of HSL activity. Likewise, plasma epinephrine increased during exercise (P < 0.05) and was higher in men than in women during the end of the exercise bout (P < 0.05). We conclude that, although HSL expression and Ser(659) phosphorylation in skeletal muscle during exercise is sex specific, total muscle HSL activity measured in vitro was similar between sexes. The higher basal IMTG content in women compared with men is therefore the best candidate to explain the higher IMTG net hydrolysis during exercise in women.
Roepstorff
Carsten
C
The Copenhagen Muscle Research Centre, Department of Human Physiology, Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark. croepstorff@ifi.ku.dk
Donsmark
Morten
M
Thiele
Maja
M
Vistisen
Bodil
B
Stewart
Greg
G
Vissing
Kristian
K
Schjerling
Peter
P
Hardie
D Grahame
DG
Galbo
Henrik
H
Kiens
Bente
B
D000328:Adult; D002352:Carrier Proteins; D004789:Enzyme Activation / Q000502:physiology; D004837:Epinephrine / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005227:Fatty Acids / Q000097:blood; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D005990:Glycerol / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology*; D009638:Norepinephrine / Q000097:blood; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011659:Pulmonary Gas Exchange; D012146:Rest / Q000502:physiology; D012694:Serine / Q000378:metabolism; D012727:Sex Characteristics; D002787:Sterol Esterase / Q000235:genetics* / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
D002352:Carrier Proteins; D005227:Fatty Acids; D007328:Insulin; D000070778:Perilipin-1; D010750:Phosphoproteins; D014280:Triglycerides; D012694:Serine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D002787:Sterol Esterase; D005990:Glycerol; D009638:Norepinephrine; D004837:Epinephrine