Expression of leptin receptor isoforms and effects of leptin on the proliferation and hormonal secretion in human pituitary adenomas.
OBJECTIVE
To pursue whether leptin regulates anterior pituitary cells, we studied the ex vivo expression of several isoforms of the leptin receptor (OB-R) as well as the in vitro effects of leptin administration in human pituitary adenomas.


METHODS
OB-R mRNA expression and in vitro response to leptin were studied in 39 pituitary macroadenomas.


RESULTS
All 4 OB-R subtypes were expressed in most adenomas. The expression was significantly more pronounced in GH-secreting adenomas as compared to non-functioning tumor cells (p < 0.05). Leptin administration in vitro did not significantly influence cell proliferation or the secretion of GH, FSH, LH or alpha-subunit.


CONCLUSIONS
(1) Several isoforms of the OB-R, including the signal transducing full-length receptor, are expressed in most human pituitary adenomas. (2) This expression ex vivo is not associated with significant effects of leptin in vitro.
Medical Department M (Endocrinology and Diabetes) and Institute of Experimental Clinical Research, Aarhus University Hospital, Aarhus, Denmark.
M T
MT
Kristiansen
L R
LR
Clausen
S
S
Nielsen
O
O
Blaabjerg
T
T
Ledet
L M
LM
Rasmussen
J O L
JO
Jørgensen
D000236:Adenoma / Q000378:metabolism / Q000503:physiopathology*; D002455:Cell Division / Q000187:drug effects; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D015292:Glycoprotein Hormones, alpha Subunit / Q000378:metabolism; D019382:Human Growth Hormone / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007536:Isomerism; D020738:Leptin / Q000378:metabolism* / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000378:metabolism / Q000503:physiopathology*; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics*; D054411:Receptors, Leptin; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D015292:Glycoprotein Hormones, alpha Subunit; C515448:LEPR protein, human; D020738:Leptin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D019382:Human Growth Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone