Effect of insulin on rat ovarian leptin expression by immunohistochemical staining.
OBJECTIVE
Leptin and insulin may interact in regulating ovarian steroid synthesis. The objective of this study was to investigate immunohistochemical staining of leptin in normal rat ovarian tissues and in rats treated with insulin and insulin plus human chorinoic gonadotropin (hCG).


METHODS
Paraffin blocks of rat ovarian tissues from a previous study, in which 18 adult, female Wistar rats with an average weight of 250 g were divided into three groups to receive either saline solution, human insulin (2 U/day) or human insulin (2 U/day) plus hCG (4 U/day) for 4 weeks, were used in this study to compare the effects on leptin staining. The results were analysed using a semiquantitative scoring system, such as mild, moderate and strong.


RESULTS
No staining was observed in granulosa cells and theca interna cells of normal ovarian tissues. Theca externa cells had mild staining intensity (+), corpus luteum had moderate (+ +) and stroma had mild (+) staining intensity. Histological structure was impaired in the insulin group, luteinized cells had mild staining, there was no difference in other cell groups. Only theca externa cells of the developing follicles were stained in insulin plus hCG group, luteinized cells again had mild staining.


CONCLUSIONS
Besides damaging the rat ovarian structure, insulin reduced staining intensity of leptin in luteinized cells. Insulin may stimulate ovarian steroid synthesis not only through its own receptors, but also by acting on the leptin expression of these cells.
Kuscu
Naci Kemal
NK
Department of Obstetrics and Gynaecology, School of Medicine, Celal Bayar University, Manisa, Turkey. kemal.kuscu@bayar.edu.tr
Ozbilgin
Kemal
K
Inan
Sevinc
S
Giray
Gulsen
G
Ceylan
Evren
E
Koyuncu
Faik
F
D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D020738:Leptin / Q000378:metabolism*; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013194:Staining and Labeling
D006063:Chorionic Gonadotropin; D007328:Insulin; D020738:Leptin