Adipocyte turnover: relevance to human adipose tissue morphology.
OBJECTIVE
Adipose tissue may contain few large adipocytes (hypertrophy) or many small adipocytes (hyperplasia). We investigated factors of putative importance for adipose tissue morphology.


METHODS
Subcutaneous adipocyte size and total fat mass were compared in 764 subjects with BMI 18-60 kg/m(2). A morphology value was defined as the difference between the measured adipocyte volume and the expected volume given by a curved-line fit for a given body fat mass and was related to insulin values. In 35 subjects, in vivo adipocyte turnover was measured by exploiting incorporation of atmospheric (14)C into DNA.


RESULTS
Occurrence of hyperplasia (negative morphology value) or hypertrophy (positive morphology value) was independent of sex and body weight but correlated with fasting plasma insulin levels and insulin sensitivity, independent of adipocyte volume (beta-coefficient = 0.3, P < 0.0001). Total adipocyte number and morphology were negatively related (r = -0.66); i.e., the total adipocyte number was greatest in pronounced hyperplasia and smallest in pronounced hypertrophy. The absolute number of new adipocytes generated each year was 70% lower (P < 0.001) in hypertrophy than in hyperplasia, and individual values for adipocyte generation and morphology were strongly related (r = 0.7, P < 0.001). The relative death rate (approximately 10% per year) or mean age of adipocytes (approximately 10 years) was not correlated with morphology.


CONCLUSIONS
Adipose tissue morphology correlates with insulin measures and is linked to the total adipocyte number independently of sex and body fat level. Low generation rates of adipocytes associate with adipose tissue hypertrophy, whereas high generation rates associate with adipose hyperplasia.
Department of Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden.
Erik
E
Arner
Pål O
PO
Westermark
Kirsty L
KL
Spalding
Tom
T
Britton
Mikael
M
Rydén
Jonas
J
Frisén
Samuel
S
Bernard
Peter
P
Arner
D017667:Adipocytes / Q000166:cytology* / Q000502:physiology*; D000273:Adipose Tissue / Q000033:anatomy & histology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001835:Body Weight; D048429:Cell Size; D005215:Fasting; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology; D013851:Thinness / Q000503:physiopathology; D055815:Young Adult
D007328:Insulin