Relationships between the serum levels of soluble leptin receptor and free and bound leptin in non-pregnant women of reproductive age and women undergoing controlled ovarian hyperstimulation.
BACKGROUND
The aim of this study was to investigate the relationships between the serum levels of soluble leptin receptor (SLEPR), and total, free and bound leptin, and the change in the serum SLEPR level during an IVF cycle.


METHODS
Serum concentrations of leptin and SLEPR were measured in 50 Japanese women of reproductive age, and 20 patients participating in an IVF programme. The total leptin was fractionated into free and bound portions by gel filtration chromatography.


RESULTS
The SLEPR level was negatively correlated with the body mass index (BMI) (r = -0.548, P < 0.0001), total leptin (r = -0.433, P < 0.0001), the percentage of free leptin (r = -0.732, P < 0.0001) and the absolute free leptin concentration (r = -0.506, P < 0.0001). The SLEPR level was positively correlated with the percentage of bound leptin (r = 0.730, P < 0.0001), whereas there was little variation in the absolute bound leptin concentration, regardless of the BMI or SLEPR concentration. During the IVF cycle, total and free leptin elevated during maximal ovarian stimulation, whereas there was no significant difference in the SLEPR concentration.


CONCLUSIONS
The results demonstrate a skillful mechanism where a change in the serum SLEPR level regulates, in part, the biological activity of leptin in the circulation.
Kado
Noriko
N
Department of Obstetrics and Gynecology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
Kitawaki
Jo
J
Koshiba
Hisato
H
Ishihara
Hiroaki
H
Kitaoka
Yui
Y
Teramoto
Mariko
M
Honjo
Hideo
H
D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007247:Infertility, Female / Q000097:blood* / Q000473:pathology / Q000628:therapy*; D020738:Leptin / Q000097:blood*; D008875:Middle Aged; D009994:Osmolar Concentration; D010062:Ovulation Induction; D011956:Receptors, Cell Surface / Q000097:blood* / Q000737:chemistry; D054411:Receptors, Leptin; D012995:Solubility
C515448:LEPR protein, human; D020738:Leptin; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin