[The effects of glucocorticoids and insulin on serum leptin level and its diurnal rhythmicity].
OBJECTIVE
To investigate the effects of glucocorticoids and insulin on serum leptin level and its diurnal rhythmicity in patients with Cushing's syndrome and obesity as well as in normal subjects.


METHODS
Fifteen patients with Cushing's syndrome and 10 with obesity as well as 9 normal subjects were investigated, with their serum leptin, cortisol and insulin levels measured 6 times a day (8:00, 12:00, 16:00, 20:00, 24:00, 3:00).


RESULTS
The diurnal rhythmicity of serum leptin was still preserved in all the three groups, with peak appearing at 24:00 approximately 3:00 and nadir at 8:00 approximately 12:00. However, the relative diurnal excursion was negatively correlated with body mass index (BMI). The peak positive effects of insulin on leptin secretion delayed by 4 to 8 hours.


CONCLUSIONS
Glucocorticoids can increase serum leptin levels, but the changes of the diurnal rhythmicity of cortisol do not affect the diurnal rhythmicity of leptin. The relative diurnal excursion of leptin is negatively correlated with body fat, i.e, the fatter subjects usually have the blunter leptin diurnal rhythmicity. Insulin exerts an effect on leptin secretion in a delayed manner, indicating its role in maintaining the diurnal rhythmicity of serum leptin.
Wang
Qidi
Q
Shanghai Institute of Endocrinology, Ruijin Hospital, Shanghai Second Medical University, Shanghai 200025, China.
Chen
Mingdao
M
Hu
Renming
R
Tang
Jinfeng
J
Li
Fengying
F
Luo
Bangyao
B
D000328:Adult; D015992:Body Mass Index; D002940:Circadian Rhythm; D003480:Cushing Syndrome / Q000097:blood*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007328:Insulin / Q000097:blood*; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D012737:Sex Factors
D007328:Insulin; D020738:Leptin; D006854:Hydrocortisone