Insulin-sensitizing effects of exercise on adiponectin and retinol-binding protein-4 concentrations in young and middle-aged women.
BACKGROUND
Exercise training enhances insulin sensitivity. Changes in retinol-binding protein-4 (RBP4) and adiponectin levels are linked to insulin resistance.


OBJECTIVE
We tested whether the insulin-sensitizing effect of exercise is associated with age-related changes in circulating RBP4 and adiponectin levels in women.


METHODS
We studied 36 healthy young (22.4 +/- 2.8 yr) and 38 middle-aged (59.8 +/- 5.9 yr) women. All subjects performed 60 min of aerobic exercise three times per week for 10 wk at about 70% maximal exercise capacity.


RESULTS
After a 10-wk training program, maximal exercise capacity was significantly increased in both young and middle-aged women, suggesting increased oxidative capacity. Insulin sensitivity was also improved, as indicated by decreases in plasma insulin levels and homeostasis model assessment for insulin resistance index. Serum adiponectin and RBP4 concentrations were increased and decreased more in older than younger women, respectively (P < 0.01). Concurrently, circulating transthyretin levels were also decreased in older subjects in response to exercise training. The older women showed higher correlations between changes in adiponectin or RBP4 levels and obesity indices or metabolic parameters than the younger group. When subjects showing increasing adiponectin or decreasing RBP4 levels were classified as responders, there were higher correlations between these changes in responders than in nonresponders.


CONCLUSIONS
We conclude that the mechanism for the insulin-sensitizing effects of exercise could involve increased adiponectin and reduced RBP4 levels in exercise-trained women. These data suggest that alterations in circulating RBP4 and adiponectin levels could play an important role in regulating insulin sensitivity.
Lim
Soo
S
Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 28 Yongon-dong Chongno-gu, Seoul, Korea.
Choi
Sung Hee
SH
Jeong
In-Kyong
IK
Kim
Jae Hyeon
JH
Moon
Min Kyong
MK
Park
Kyong Soo
KS
Lee
Hong Kyu
HK
Kim
Young-Bum
YB
Jang
Hak Chul
HC
D052242:Adiponectin / Q000097:blood* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008875:Middle Aged; D011228:Prealbumin / Q000032:analysis; D054839:Retinol-Binding Proteins, Plasma / Q000032:analysis* / Q000378:metabolism
D052242:Adiponectin; D011228:Prealbumin; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma