Dexamethasone ester treatment alters insulin-like growth factor-I, its binding proteins and thyroid status in finishing calves

Abstract

Dexamethasone ester treatment alters insulin-like growth factor-I, its binding proteins and thyroid status in finishing calves. Can. J. Anim. Sci. 80: 329-335. To improve carcass quality in finishing calves, some breeders use preparations containing corticoids alone or in association with other growth promoters. We have investigated the effects of dexamethasone treatment on insulin-like growth factor-I (IGF-I), IGF-binding proteins (IGFBP-2 and -3) and thyroid hormones (T 3 , T 4 , free T 4 ). Limousine male calves were allocated to a control group (C) (n = 18) and a group (n = 18) that received dexamethasone esters (DEX). Blood and hepatic tissue samples were collected at slaughtering. Thyroid hormones and IGF-I plasma levels were measured by RIA and IGFBPs were evaluated by immunoblotting. Hepatic type I 5′deiodinase (5′D-I) activity was determined by enzyme assay and hepatic expression of mRNA for GH receptor, IGF-I, IGFBP-2, IGFBP-3 and type I deiodinase (D-I) was evaluated by dot blot analysis. Plasma IGF-I and IGFBP-3 levels were reduced by the DEX treatment (P < 0.001 and P < 0.01, respectively) while IGFBP-2 was unaffected. Significant plasma changes for IGF-I and IGFBP-3 were not corroborated by hepatic mRNA levels, for which only a slight non-significant decrease was noted. Growth hormone receptor mRNA expression was increased after treatment (P < 0.01). T 3 plasma level was higher in DEX animals (P < 0.05) than in C calves. Finally, treatment increased 5′D-I activity in the hepatic tissue (P < 0.001) and seemed to also affect D-I mRNA expression (P = 0.1). In conclusion, dexamethasone ester injection in calves altered some of their endocrinological parameters; this could explain the catabolic action of corticoids in the bovine species.

Potential of Treatment-Specific Protein Biomarker Profiles for Detection of Hormone Abuse in Cattle

“…The effects of glucocorticoids on IGF-1 levels at different life stages were studied before. Acute glucocorticoid treatment of newborn animals resulted in a stimulation of the somatotropic axis and increased IGF-1 levels. , In early life stages, glucocorticoid administration had an inhibiting effect on plasma IGF-1 concentrations. , Nevertheless, glucocorticoid treatment of adults resulted in increased IGF-1 levels again, , which is also supported by the results of our study, in which 17–22-month-old cattle were treated. As already described by Hammon et al, IGF-1 response upon glucocorticoid treatment depends on age, dose, and duration of the treatment .…”

“…The biomarker panel of the 4-plex FCIA consisted of insulin-like growth factor 1 (IGF-1), IGF binding protein 2 (IGFBP2), osteocalcin, and antibodies produced by cows upon rbST treatment (anti-rbST antibodies). This biomarker panel was specifically developed for the detection of rbST abuse in dairy cattle, and biomarkers were chosen on the basis of information from the literature stating specific changes in biomarker concentrations after somatotropin treatment. − Nevertheless, three of these four biomarkers, namely IGF-1, IGFBP2, and osteocalcin, are also known to be influenced by steroid hormone treatments such as glucocorticoids and sex steroids. ,− IGF-1 and IGFBP2 are members of the somatotropin/IGF axis, which is usually involved in growth-related mechanisms and is thereby affected by growth-inducing or -repressing substances, such as growth-promoting steroids. ,,,,, One possible target of somatotropin, IGF-1, and steroid hormone action is bone, which reacts with an increase or decrease in bone turnover. Osteocalcin is a marker of bone turnover and, therewith, osteocalcin concentrations respond upon administration of bone turnover altering drugs. ,, Therefore, the selected biomarkers might also be influenced not only by rbST but also by other growth-promoting steroids.…”

Effects of dexamethasone and colostrum intake on the somatotropic axis in neonatal calves

“…However, our data correspond to findings in neonatal pigs (10) and growing bulls (43) treated with Dexa. However, Coxam et al (15) did not find an effect of cortisol on plasma IGF-I concentrations in calves, and Dexa decreased plasma IGF-I concentrations in cows and finishing calves (2,33). Therefore, effects of glucocorticoids on IGF-I plasma concentrations are variable and may depend on treatment-dose (34) and age (9).…”

“…We expected increased IGFBP-3 concentrations in Dexa-treated calves, because IGF-I and insulin were elevated and are known to stimulate IGFBP-3 production (12,27). However, glucocorticoids reduced IGFBP-3 plasma concentrations in finishing calves (2), and Dexa did not influence hepatic IGFBP-3 mRNA in neonatal pigs (10). Therefore, IGFBP-3 levels in neonatal calves do not support the view of an accelerated maturation of the somatotropic axis by colostrum feeding or Dexa treatment.…”

The effect of concurrent corticosteroid induced immuno-suppression and infection with the intestinal parasite Trichostrongylus colubriformis on food intake and utilization in both immunologically naïve and competent sheep

“…The suppression of immunity through the use of corticosteroids was, of necessity, a crude approach, and disturbances to intake, wool growth, live-weight gain, nutrient partitioning and protein metabolism as well as to the immune response were anticipated (Thompson et al, 1995;Bertozzi et al, 2000), and are discussed later.…”