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Title: Investigation into the involvement of growth hormone in genetic differences in growth and size
Author: Bootland, Lorna H.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1992
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Lines selected high or low on lean body mass (P-Lines) or on carcass fat (F-Lines) for more than 30 generations were treated with recombinant bovine growth hormone (GH) to obtain information about the effects of selection on GH levels and responsiveness. All lines responded to GH with an increase in final body weight. In the lean mass selected lines the high line increased more than the low, but the increase relative to initial weight was similar in both lines (10-15% ). GH did not have a significant effect on gonadal fat percentage. Further investigations involved the lean mass selected lines only. Weights were recorded on a daily basis from birth to weaning at 21 days, to investigate growth before mice become responsive to GH at 14 days. The high line had a mean litter size approximately twice that of the low line, and a mean birth weight approximately 50% greater than the low line. The difference in total litter weight at birth is greater (3 to 4 fold) than the difference in adult body weight (approximately 3 fold) suggesting that there may be between line differences in individual effects on in utero growth rates as well as differences due to maternal effects. Also an increase in the rate of gain was observed for both lines at approximately 18 days of age. An increase was also observed in GH deficient little dwarf mice from the high P-Line, and hence is not due to GH. The increase in the rate of weight gain is greater in the wild type mice than in the little mice suggesting GH acts to magnify the effects of whatever causes the increase. Plasma GH levels were assayed, the high P-Line had lower levels of GH at 4, 5 and 7 weeks of age than the low P-Line. As IGF-I levels become GH inducible at about 14 days of age and the lines experience an increase in the rate of weight gain, which is greater in the high line than in the low line, at about 18 days it appeared possible that IGF-I levels differed between the lines.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available