Comparison of GH-stimulation by GH-RH(1-29)NH2 and an agmatine29 GH-RH analog, after intravenous, subcutaneous and intranasal administration and after pulmonary inhalation in rats.
Many studies have shown that human GH-RH(1-29)NH2 possesses full intrinsic activity of GH-RH(1-44)NH2 in vitro and in vivo. This investigation was performed to evaluate the efficacy of GH-RH(1-29)NH2 given by different routes of administration in stimulating GH release in rats. In each case GH-RH(1-29)NH2 was administered intravenously, subcutaneously, intranasally and by pulmonary inhalation at two different doses to groups of seven males rats. At a dose of 150 micrograms/kg GH-RH(1-29)NH2, the magnitude of GH response was significantly higher for the pulmonary inhalation group (355 +/- 33.2 ng GH/mL) than for the subcutaneous group (246 +/- 36 ng GH/mL) or for the intranasal group (175 +/- 30 ng GH/mL). The group injected intravenously with GH-RH(1-29)NH2 at a dose of 2.5 micrograms/kg showed the highest response, GH levels reaching 877.2 +/- 115 ng/mL. A similar pattern of responses was obtained for the superactive GH-RH(1-29) agmatine29 analog, MZ-3-149, at doses that were 50 times lower. Our results indicate a high bioavailability of GH-RH(1-29)NH2 or analog MZ-3-149 administered by a convenient pulmonary inhalation route. The GH-releasing effect of GH-RH(1-29)NH2 or analog MZ-3-149 delivered by pulmonary inhalation is superior to subcutaneous and intranasal administration.
Pinski
J
J
Endocrine, Polypeptide and Cancer Institute, VA Medical Center, New Orleans.
Yano
T
T
Groot
K
K
Zsigo
J
J
Rekasi
Z
Z
Comaru-Schally
A M
AM
Schally
A V
AV
D000280:Administration, Inhalation; D000281:Administration, Intranasal; D000818:Animals; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017337:Sermorelin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*
C080503:MZ 3-149; D017337:Sermorelin; D013006:Growth Hormone