Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2007) 13 P128

SFEBES2007 Poster Presentations Growth and development (10 abstracts)

Growth in Growth Hormone (GH) deficient dwarf rats is enhanced by variable dose GH treatment

Arfa Maqsood , Andrew Whatmore , Melissa Westwood & Peter Clayton


University of Manchester, Manchester, United Kingdom.


Good growth in children is associated with large, disordered, fluctuations in GH levels from week to week (Gill et al., 1999; Gill et al., 2001). However, GH treatment regimens are restricted to daily fixed doses which may not provide optimal growth. We have used GH-deficient dwarf rats (dw/dw) to test our hypothesis that variable GH dosing will enhance growth.

Six week old, male dwarf rats (16 per group) were treated for 6 weeks with either saline or recombinant bovine GH (rbGH) given in one of 3 treatment regimens: a) a fixed daily dose of 100 μg, b) a high/low dose schedule (62 μg/d and 138 μg/d alternating weekly) or c) a daily dose between 5 and 250 μg/d randomised within each week to provide a total of 700 μg/week. Weight was measured thrice weekly and body length weekly. Animals were sacrificed after 6 weeks, organs weighed and tibia and femur lengths measured.

After 1 week, all GH treated groups showed improved growth with regard to both length (P=0.001) and weight (P=0.002) compared to controls. After 6 weeks, only animals given a random dose showed significant enhancement of total body length (P=0.047) or weight gain (P=0.025) compared to controls.

At 6 weeks, both tibial length (P=0.001) and width (P=0.007) were significantly enhanced in group c whilst femur length was significantly enhanced in both groups b (P=0.003) and c (P=0.005).

No significant differences were detected in heart or fat weights between treatment groups. However, the weights of lungs (−ve; P=0.001), muscles (+ve; P=0.001), livers (+ve; P=0.022), and kidneys (+ve; P=0.048) showed significant treatment dependent variation with groups b and c being most efficacious.

We demonstrate that a random dosing regimen has more potent anabolic effects on weight, long bone growth and GH-sensitive organ weight than fixed daily doses. This suggests that a random GH dosing regimen may improve children’s growth performance for the same overall GH dose.

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