Modulatory effects of a synthetic steroid (tibolone) and estradiol on spontaneous and GH-RH-induced GH secretion in postmenopausal women.
OBJECTIVE
Since hormonal replacement therapy (HRT) affects plasma GH levels, the present study aimed to verify the effect of tibolone, a synthetic steroid, on modulating spontaneous and growth hormone releasing hormone (GH-RH) induced GH secretion.


METHODS
Postmenopausal women (n = 30) were enrolled and randomly subdivided in three groups (n = 10 each group): (1) treated with transdermal estradiol (50 micrograms) (Dermestrill, Rottapharm, Monza, Italy) biweekly; (2) treated with transdermal estradiol (100 micrograms) (Dermestrill, Rottapharm, Monza, Italy) biweekly; (3) treated with tibolone 2.5 mg/day (Livial, Organon Italia, Rome, Italy). Patients underwent a GH-RH test (1 microgram/kg) and 15 of them underwent to a pulsatility study before and 5 weeks after treatment.


RESULTS
Mean (+ S.E.M.) GH plasma levels increased in all patients after any type of HRT. GH response to GH-RH stimulation (expressed as maximal response to GH-RH or as delta value) was similar in the three groups while significant changes occurred in spontaneous pulsatile GH release. Tibolone and both dosages of transdermal estradiol significantly reduced GH pulse frequency and increased pulse amplitude.


CONCLUSIONS
The reduced plasma GH levels observed during postmenopause are probably related to a reduced endogenous GH-RH and not to a reduced pituitary ability to respond to GH-RH. In addition tibolone, as well as transdermal estradiol, are effective in restoring the spontaneous GH episodic release.
Genazzani
A D
AD
University of Modena, Italy. algen@unimo.it
Gamba
O
O
Nappi
L
L
Volpe
A
A
Petraglia
F
F
D000279:Administration, Cutaneous; D045930:Anabolic Agents / Q000008:administration & dosage*; D015992:Body Mass Index; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage*; D015914:Estrogen Replacement Therapy / Q000009:adverse effects* / Q000379:methods; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage*; D019382:Human Growth Hormone / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood; D009652:Norpregnenes / Q000008:administration & dosage*; D017698:Postmenopause / Q000097:blood* / Q000187:drug effects
D045930:Anabolic Agents; D009652:Norpregnenes; D019382:Human Growth Hormone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013007:Growth Hormone-Releasing Hormone; C027385:tibolone