Influence of cortisol, gonadal steroids and an energy deficit on biochemical indicators of bone turnover in Swine

Selective glucocorticoid receptor modulation inhibits cytokine responses in a canine model of mild endotoxemia

Selective glucocorticoid receptor modulators (GRMs) promise to reduce adverse events of glucocorticoids while maintaining anti-inflammatory potency. The present study tested the anti-inflammatory activity of two novel non-steroidal GRMs (GRM1: BI 607812 BS, GRM2: BI 653048 BS*H3PO4) in comparison to prednisolone in a canine model of low dose endotoxemia. This study compared the anti-inflammatory and pharmacokinetic profile of escalating daily oral doses of GRM1 (1, 2.5, 5 and 10mg/kg) and GRM2 (0.1, 0.25 and 1mg/kg) with prednisolone (0.25 and 0.5mg/kg) and placebo after intravenous infusion of endotoxin (0.1μg/kg) to Beagle dogs. This was followed by a 14-day evaluation study of safety and pharmacokinetics. Endotoxin challenge increased TNF-α ∼2000-fold and interleukin-6 (IL-6) 100-fold. Prednisolone and both GRMs suppressed peak TNF-α and IL-6 by 71-82% as compared with placebo. The highest doses of GRM1 and GRM2 reduced the mean body temperature increase by ∼30%. The endotoxin-induced rise in plasma cortisol was strongly suppressed in all treatment groups. Pharmacokinetics of both GRMs were non-linear. Adverse effects of endotoxemia such as vomiting were mitigated by GRM2 and prednisolone, indicating an antiemetic effect. During the 14-day treatment period, the adverse event profile of both GRMs appeared to be similar to prednisolone. Both GRMs had anti-inflammatory effects comparable to prednisolone and showed good safety profiles. Compounds targeting the glucocorticoid receptor selectively may provide an alternative to traditional glucocorticoids in the treatment of inflammatory disease.

Effects of cortisol secreted via a 12-h infusion of adrenocorticotropic hormone on mineral homeostasis and bone metabolism in ovariectomized cows

To evaluate the effects of endogenously secreted cortisol on mineral homeostasis and bone metabolism in cows, 4 ovariectomized Holstein cows were infused for 12 h with either an adrenocorticotropic hormone (ACTH) solution (0.5 mg/2 L isotonic NaCl solution per cow) or isotonic NaCl solution in a 2×2 crossover design. ACTH infusion stimulated cortisol secretion and increased plasma cortisol concentrations for 18 h (P<0.001), leading to an elevated plasma glucose concentration until 36 h (P<0.001). Plasma calcium and magnesium concentrations in ACTH-infused cows fluctuated within normal ranges, whereas hypophosphatemia was observed unequivocally. The biochemical bone resorption markers tartrate-resistant acid phosphatase 5b and hydroxyproline decreased following ACTH infusion (P<0.001 and P=0.003, respectively). Similarly, the bone formation marker, bone-specific alkaline phosphatase, decreased continuously until 72 h after the ACTH infusion (P<0.001). These results demonstrate that increased secretion of cortisol via a 12-h ACTH infusion disrupted homeostasis of inorganic phosphate and suppressed bone metabolism in ovariectomized cows without involving gonadal steroid hormones.

Effects of Dietary Cation-Anion Difference on Blood Cortisol and ACTH Levels in Reproducing Ewes

Formulation of rations to induce a compensated metabolic acidosis in the post-partum cow has proved a useful strategy for prevention of milk fever. Such acidification improves the ability of the animal to maintain calcium homeostasis by promoting the absorption of calcium from the intestine and mobilization of calcium from the bone. In humans, an acidogenic diet results in mild metabolic acidosis in association with a state of cortisol excess and this increase in plasma cortisol may increase bone catabolism. The objective of our experiment was to induce acidification by anionic salt supplementation and to study the effects of anionic supplementation on plasma cortisol and adrenocorticotropic hormone (ACTH) levels in sheep. Twenty-seven twin-bearing sheep were assigned to two experimental groups and a control group, depending on dietary cation-anion difference (DCAD) (+272.6, -88.9 and +164.5 mEq/kg DM respectively). Sheep assigned to each dietary treatment received their respective rations beginning 6 weeks pre-partum and continuing until 12 days post-partum. Anionic diet induced a non-respiratory systemic acidosis in association with a mild increase in plasma cortisol concentration without changes in plasma ACTH levels. Our data suggest that the mild hypercortisolism observed in sheep fed the anionic diet may not be an effector for bone resorption induced by anionic salts. A mild hypercortisolism of this magnitude may lead to osteoporosis but this might require many years of adrenal hypersecretion while anionic salts are only used during the last weeks of pregnancy.

Effects of dexamethasone application in growing pigs on hormones, N-retention and other metabolic parameters

Many single effects of glucocorticoids are known but complex metabolic reactions in pigs in response to a glucocorticoid challenge were not reported. Seven pigs (mean weight 69 kg) with indwelling catheters were kept in metabolic crates. After a 7-day control period they were fed for 9 days with 0.4 mg dexamethasone (dex) per kg body weight daily, followed by another 9-day post-treatment period. Hormones and metabolic parameters were continuously determined in urine or blood plasma. Treatment significantly changed all parameters except non-esterified fatty acids. Cortisol decreased from 84.5 to 4.9 nmol/l, insulin-like growth factor I (IGF-I) from 17.5 to 10.8 nmol/l and aldosterone from 0.36 to 0.13 nmol/l. The N-retention decreased from 1.07 to 0.53 g/kg(0.75) and hydroxyproline from 2.97 to 1.05 mmol/day. An increase was found for urine volume (5.2 versus 13.6 l/day), urea-N (0.90 versus 1.43 g/kg(0.75)), allantoin (6.40 versus 8.75 mmol/day), glucose (3.9 versus 4.34 mmol/l) and insulin (6.21 versus 11.16 mU/l). In the post-treatment period IGF-I revealed a compensatory pattern (control period versus post-treatment period: 17.5 versus 22.9 nmol/l) whereas the other parameters were not significantly elevated. Data suggest that dex increased N-excretion both by inhibiting mitosis and resynthesis of proteins partly via a reduced collagen synthesis. Increased allantoin concentrations additionally pointed to increased apoptosis.