Submitted to: Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/1998
Publication Date: N/A
Interpretive Summary: Wasting syndrome associated with infection causes producers and consumers significant economic loss. Growth hormone is suggested as a possible therapeutic agent to offset tissue losses associated with undernutrition. Other data from our laboratory demonstrated that the severity of responses to bacterial extracts ( endotoxins ) was reduced in beef calves treated with growth hormone prior to extract injection. However, there are no data that suggest if growth hormone has any beneficial effect in young animals that maintain chronic active parasitic infections. The present study was designed to examine how growth hormone treatment would influence the course of disease using a calf model of a parasitic disease known to increase tissue losses. Daily administration of GH to these young calves did not prevent lean tissue losses associated with the infection but did facilitate increased fat losses, possibly an attempt to increase available energy for metabolism associated with complication of reduced food intake in the infected calves. The present data argue that the use of growth hormone during infection may need to be validated for specific diseases and ages of animals.
Technical Abstract: A multistage protozoan parasitic disease was used as a cachexia model to study the effects of daily administration of bovine growth hormone ( GH ) on endocrine and body composition changes of young calves from the onset of the acute phase response (APR). Male calves averaging 127.5+2 kg body weight were assigned to control,ad libitum fed, noninfected (C);ad libitum fed,infected (250,000 oocysts Sarcocystis cruzi ,per os , I);noninfected,pair- fed to a matched I ( PF ) treatments and these respective same treatments in calves injected daily with GH ( 12.5 mg/h/d,im) designated as CGH , IGH and PFGH . Average daily carcass protein gains were 123, 52, 109, 124, 48 and 67 g/day and average daily carcass fat gains were 85, 11, 43, 71, -23 and 29 g/day for C,I, PF , CGH , IGH and PFGH ,respectively. Rectus femoris was highly refractory to catabolic effects of infection while psoas major was significantly catabolized during infection. Plasma IGF -I declined well below d-20 values in all infected calves from the onset of the APR through the end of the study. The decrease in plasma IGF -I concentrations in I and IGH was highly correlated with the magnitude of the fever response. Hepatic mRNA for GH receptor and IGF -I was decreased in infected calves. The data suggest that effects of GH and parasitism on tissue metabolism during disease may vary among different specific tissue pools. Furthermore,the onset of APR overrode the capacity for GH to maintain elevated plasma concentrations of IGF -I,an effect not readily explained through GH -receptor binding.