Immunohistochemical localization of two types of fatty acid-binding proteins in rat ovaries during postnatal development and in immature rat ovaries treated with gonadotropins.
BACKGROUND
The ovary of adult rats expresses two types of cytoplasmic fatty acid binding proteins (FABP), i.e., heart FABP (H-FABP) and intestinal 15 kDa protein (I-15P). We studied immunohistochemically the cellular localizations of these FABPs in the ovaries of rats at various postnatal ages and in the ovaries of immature (3-week-old) rats treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG).


METHODS
The cryosections of ovaries were incubated with polyclonal antibodies against H-FABP and I-15P, and the immunoreactions were visualized at both light and electron microscopic levels.


RESULTS
The immunoreactivity for H-FABP occurred temporarily in the follicular epithelial (granulosa) cells from 3 days to 2 weeks post partum, and then was localized exclusively to the theca/interstitial gland cells from 2 weeks to adulthood. In contrast, the immunoreactivity for I-15P appeared temporarily in a small subset of theca/interstitial gland cells from 2 to 3 weeks, disappeared at 4 weeks, and was localized exclusively to the corpus luteum cells after the onset of ovulation in the animal around 5 weeks. In the immature rat ovaries induced to ovulate by treatment with gonadotropins, I-15P-immunoreactive cells were first recognized in the luteinized granulosa layer of large preovulatory follicles, and increased in number progressively in the developing corpora lutea after the ovulation.


CONCLUSIONS
Two types of FABPs are expressed in distinct steroid-producing cell types of rat ovary, and their expressions seem to be regulated in coincidence with the expressions of respective steroid hormones. These results suggest that FABPs play specific roles in the ovarian hormone synthesis.
Iseki
S
S
Department of Anatomy, School of Medicine, Kanazawa University, Japan.
Amano
O
O
Fujii
H
H
Kanda
T
T
Ono
T
T
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006062:Gonadotropins / Q000494:pharmacology*; D006064:Gonadotropins, Equine / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010053:Ovary / Q000187:drug effects / Q000378:metabolism*; D010062:Ovulation Induction; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
D002352:Carrier Proteins; D006063:Chorionic Gonadotropin; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D006062:Gonadotropins; D006064:Gonadotropins, Equine; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins