Neuroendocrine and cardiovascular responses to high-dose corticosteroid therapy in canine endotoxin shock

Prednisolone has a positive effect on the kidney but not on the liver of brain dead rats: a potencial role in complement activation

Background

Contradictory evidence has been published on the effects of steroid treatments on the outcomes of kidney and liver transplantation from brain dead (BD) donors. Our study aimed to evaluate this disparity by investigating the effect of prednisolone administration on BD rats.

Methods

BD induction was performed in ventilated rats by inflating a Fogarty catheter placed in the epidural space. Prednisolone (22.5 mg/kg) was administered 30 min prior to BD induction. After four hours of determination of BD: serum, kidney and liver tissues samples were collected and stored. RT-qPCR, routine biochemistry and immunohistochemistry were performed.

Results

Prednisolone treatment reduced circulating IL-6 and creatinine plasma levels but not serum AST, ALT or LDH. Polymorphonuclear influx assessed by histology, and inflammatory gene expression were reduced in the kidney and liver. However, complement component 3 (C3) expression was decreased in kidney but not in liver. Gene expression of HSP-70, a cytoprotective protein, was down-regulated in the liver after treatment.

Conclusions

This study shows that prednisolone decreases inflammation and improves renal function, whilst not reducing liver injury. The persistence of complement activation and the negative effect on protective cellular mechanisms in the liver may explain the disparity between the effects of prednisolone on the kidney and liver of BD rats. The difference in the molecular and cellular responses to prednisolone administration may explain the contradictory evidence of the effects of prednisolone on different organ types from brain dead organ donors.

Establishment of a low dose canine endotoxemia model to test anti-inflammatory drugs: effects of prednisolone

Infusion of low doses of lipopolysaccharide (LPS) in human volunteers provides a standardised model to study novel anti-inflammatory drugs. However, low dose endotoxemia is not well characterised in animals larger than rodents and trials with immunomodulating substances are scarce. We conducted a dose-finding study to establish a canine endotoxemia model combining optimal cytokine response with minimal burden for the animals. We thereafter evaluated the pharmacodynamics and pharmacokinetics (PK) of prednisolone. For dose-finding, dogs randomly received a single bolus of 0.03, 0.1 or 1.0 microg/kg BW LPS i.v. The second part was a randomised, placebo controlled trial with 4 parallel groups. Either 0.25, 0.5 or 5mg/kgBW prednisolone or placebo were given for 3 days. On day 3, all animals received 0.1microg/kg BW LPS i.v. Blood was sampled to measure interleukin 6 (IL-6) and tumor necrosis factor-alpha, C-reactive protein, prednisolone and cortisol concentrations. In accordance with human endotoxemia, LPS substantially and dose-dependently increased IL-6 and TNF-alpha several 1000-fold. Prednisolone significantly attenuated the LPS-induced IL-6 and TNF-alpha responses by a maximum of 96 percent (p less than 0.03 for all treatment groups) and significantly reduced peak cortisol concentrations in a dose-dependent way (p less than 0.004 for all treatment groups). PK showed a non-linear kinetic. In conclusion, this dog model could provide a reliable setting to test experimental drugs for canine or human use.

Endogenous opiates: 1988

This paper is the eleventh installment in our annual review of the research during the past year involving the endogenous opiate system. It is concerned with nonanalgesic and behavioral studies of the opiate peptides that were published during 1988. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic functions; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical activity; locomotor activity; sex, pregnancy, and development; immunology and cancer; and other behavior.