title: Growth hormone does not prevent corticosteroid-induced changes in rat diaphragm structure and function.
abstract: The present study tested the hypothesis that growth hormone (GH), an anabolic agent, could prevent the abnormalities of diaphragm structure and function associated with short-term administration of the corticosteroid triamcinolone (TR). During a 10-day period, male rats (n = 33) were assigned to control (CTL), TR (1 mg.kg-1.day-1 im), and TR-GH (2 mg.kg-1.day-1 im) groups. Diaphragm weight was significantly reduced in the TR and TR-GH animals compared with the CTL animals, but there was no difference in the diaphragm-to-body weight ratio. Fiber type (I, IIa, and IIx/b) proportions did not differ among the three groups. However, in TR rats there was a significant reduction in the contribution of type IIx/b fibers to total diaphragm cross-sectional area due to marked atrophy (approximately 42% decrease in mean fiber cross-sectional area). There was no significant reversal of TR-induced type IIx/b fiber atrophy by concomitant GH administration. TR and TR-GH groups both exhibited a left-ward shift of the force-frequency relationship and enhanced in vitro fatigue resistance, whereas maximal specific force was unaltered. We conclude that GH does not prevent corticosteroid-induced effects on the diaphragm under these conditions, possibly as a result of reduced nutritional intake associated with TR administration.
authors.affiliation: Royal Victoria Hospital, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada.
authors.forename: B J
authors.initials: BJ
authors.lastname: Petrof
authors.forename: S B
authors.initials: SB
authors.lastname: Gottfried
authors.forename: J
authors.initials: J
authors.lastname: Eby
authors.forename: J
authors.initials: J
authors.lastname: Lamanca
authors.forename: S
authors.initials: S
authors.lastname: Levine
mesh_terms: D000818:Animals; D001835:Body Weight; D003964:Diaphragm / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005938:Glucocorticoids / Q000009:adverse effects*; D013006:Growth Hormone / Q000494:pharmacology*; D007537:Isometric Contraction / Q000187:drug effects*; D008297:Male; D009218:Myosins / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D014221:Triamcinolone / Q000009:adverse effects*
chemical_list: D005938:Glucocorticoids; D014221:Triamcinolone; D013006:Growth Hormone; D009218:Myosins