Circadian rhythm of serum vaspin in healthy male volunteers: relation to meals.
BACKGROUND
Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a novel adipokine with insulin-sensitizing effects. However, the physiological role for vaspin in human metabolic regulation remains to be established.


OBJECTIVE
We studied the 24-h profiles of circulating vaspin concentrations in relation to meal ingestion in normal adults.


METHODS
Blood samples were drawn 39 times throughout a 24-h period from 10 healthy male subjects provided with meals on a fixed schedule. On a separate day, four subjects were fasted and then provided with an unexpected meal to clarify the effect of meal consumption on serum vaspin levels. Serum vaspin concentrations were determined by ELISA.


RESULTS
Serum vaspin levels were highest in the early morning before breakfast and fell to trough levels within 2 h after breakfast. Serum vaspin levels also showed a preprandial rise and postprandial fall at lunch and dinner, although at lesser degrees than at breakfast. Intermeal vaspin concentrations reached a nadir in the mid-afternoon and showed a nocturnal rise, with peak nighttime vaspin levels being approximately 250% of nadir levels. Unscheduled food ingestion after a prolonged fast significantly reduced serum vaspin levels, suggesting that energy intake itself has a suppressive effect on serum vaspin levels. The diurnal pattern of serum vaspin concentrations was exactly reciprocal to that of insulin and of glucose.


CONCLUSIONS
Serum vaspin levels have a meal-related diurnal variation, suggesting a role for vaspin in metabolic regulation. However, the reciprocal relationship between serum vaspin and insulin may negate the importance of vaspin as an physiological insulin sensitizer.
Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Pungnap-2 dong, Songpa-gu, Seoul 138-736, Korea.
Eunheui
E
Jeong
Byung-Soo
BS
Youn
Dong Woo
DW
Kim
Eun Hee
EH
Kim
Ji Woo
JW
Park
Churl
C
Namkoong
Ji Yun
JY
Jeong
So Yoon
SY
Yoon
Joong Yeol
JY
Park
Ki-Up
KU
Lee
Min-Seon
MS
Kim
D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000097:blood; D008297:Male; D009765:Obesity / Q000097:blood / Q000378:metabolism; D019518:Postprandial Period / Q000502:physiology; D012016:Reference Values; D015843:Serpins / Q000097:blood*; D055815:Young Adult
D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; C507339:SERPINA12 protein, human; D015843:Serpins; D006854:Hydrocortisone