Plasma levels and biochemical characterisation of circulating met-enkephalin in canine endotoxin shock

Evans, S.F.; Medbak, S.; Hinds, C. J.; Tomlin, Susan; Varley, J. G.; Rees, Lesley

doi:10.1016/0024-3205(84)90063-8

Cited by 32 publications

(11 citation statements)

References 24 publications

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“…Met-enkephalin IR was eluted in two positions, one identical to met-enkephalin standard, the second not corresponding to any other peptide tested. This second peak probably consists of high molecular weight forms of metenkephalin which have been found also in the peripheral blood of dogs with experimentally induced shock (Evans et al, 1984;Medbak et al, 1987). ß-Endorphin and met-enkephalin values therefore have to be interpreted as immunoreactivity.…”

Section: Discussionmentioning

confidence: 98%

-Endorphin and met-enkephalin in plasma of cattle during pregnancy, parturition and the neonatal period

Aurich¹,

Dobrinski²,

Hoppen³

et al. 1990

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Plasma concentrations of beta-endorphin and met-enkephalin were measured, with appropriate radioimmunoassays, in cows during gestation and at parturition and in newborn calves. During pregnancy beta-endorphin immunoreactivity (IR) concentration increased, but values during the last month of gestation were not different from those at parturition. Highest met-enkephalin IR levels were obtained in cows during calving. A term Caesarean section caused an increase in plasma beta-endorphin and met-enkephalin IR concentrations, but no such increase occurred in cases of a preterm Caesarean section. In calves beta-endorphin IR values were lower before umbilical cord rupture than immediately after birth. Values decreased continuously thereafter. This was also the case for met-enkephalin IR concentrations in calves born at term. In preterm calves met-enkephalin IR values were low immediately after delivery and increased during the first hour of life. A significant correlation existed between the degree of acidosis and plasma levels of both opioid peptides in the calves. We conclude that a direct stimulation of peripheral beta-endorphin release by the pain or stress associated with calving does not seem to exist in cattle, whereas met-enkephalin seems to be more directly related to parturition. In calves the change to the extrauterine environment causes an immediate, increased release of both opioids.

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Section: Discussionmentioning

confidence: 98%

-Endorphin and met-enkephalin in plasma of cattle during pregnancy, parturition and the neonatal period

Aurich¹,

Dobrinski²,

Hoppen³

et al. 1990

Reproduction

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“…In vivo stimulation of the splanchnic nerve induces a voltage-dependent increase in adrenal vein levels of ir-metenkephalin [19], and in canine models, increases in plasma ir-metenkephalin have been demonstrated in response to both endotoxin [14] and hypovolaemic shock [5].…”

Section: Introductionmentioning

confidence: 98%

Adrenal vein and arterial levels of catecholamines and immunoreactive metenkephalin in canine endotoxin shock and their response to naloxone

et al. 1988

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The alterations in plasma levels of immunoreactive metenkephalin (ir-metenkephalin) and catecholamines in adrenal vein and arterial blood in response to endotoxin, as well as the effects of subsequent naloxone administration, have been investigated in a canine model. Animals were anaesthetised with alpha chloralose and allowed to breathe spontaneously. The left lumbar adrenal vein was cannulated and an intermittent choke allowed retrograde sampling of the adrenal effluent. Severe shock was produced by the administration of a large bolus of E. coli endotoxin (5 mg/kg) followed by a continuous infusion (2 mg/kg per hour). One hour after induction of shock the circulating volume was expanded using a colloidal gelatin solution. Thirty minutes later one group of five animals received a bolus of naloxone (2 mg/kg) followed by a continuous infusion of (1.5 mg/kg per hour), while a control group of five animals was given an equivalent volume of isotonic saline. The production of endotoxin shock was associated with marked increases in adrenal vein and systemic levels of adrenaline and noradrenaline. Naloxone administration transiently limited the fall in adrenal vein levels of adrenaline and noradrenaline (P less than 0.05) following volume replacement and was associated with a sustained increase in systemic adrenaline levels (P less than 0.05). Changes in mean arterial pressure confirmed a significant haemodynamic response to naloxone (P less than 0.05). Alterations in ir-metenkephalin levels in the adrenal vein closely followed the changes in catecholamines, whereas arterial levels rose progressively and were unaffected by naloxone. We conclude that in canine endotoxin shock the opiate antagonist naloxone can transiently increase catecholamine levels in the adrenal effluent and produce a more sustained rise in systemic adrenaline levels. Moreover, the adrenal medulla is not the only source of circulating ir-metenkephalin.

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“…Evidence is, however, gradually accumu¬ lating about its involvement in the stress response, possibly through feedback control of catecholamine secretion (Kumakura, Karoum, Guidotti & Costa, 1980). We have recently demonstrated that plasma MLI concentrations rise following insulin-induced hypoglycaemia , hypotension , artificial hyperventilation (Mason & Medbak, 1986), exercise (Howlett, Tomlin, Ngahfoong et al 1984) and endotoxic shock (Evans, Medbak, Hinds et al 1984;Watson, Varley, Tomlin et al 1986).…”

Section: Discussionmentioning

confidence: 98%

Effects of ethanol and inhibitors of its metabolism on the circulating levels of Met-enkephalin in greyhounds

Medbak

Mason²,

Rees³

1989

Journal of Endocrinology

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The mechanisms involved in the release of Met-enkephalin-like immunoreactivity (MLI) into the circulation following oral administration of ethanol and chlorpropamide were investigated in dogs. The origin of plasma MLI and the sites where it may be metabolized were also studied. Moreover, the molecular nature of circulating MLI was characterized. In conscious animals oral administration of ethanol (0.15 ml/kg) led to a significant (P less than 0.01) rise in plasma MLI concentrations in chlorpropamide-pretreated animals from a basal level of 43 +/- 6 (mean +/- S.E.M.) to a peak of 66 +/- 8 ng/l. Similar rises in MLI concentrations were observed following administration of ethanol with disulfiram and ethanol with chlorpropamide and captopril. In contrast, the administration of ethanol alone or ethanol with 4-methylpyrazole resulted in a decrease in plasma MLI concentrations. Comparisons of two different doses of i.v. acetaldehyde, the first metabolite of ethanol, showed that plasma MLI concentrations rose significantly (P less than 0.05) only after the larger dose (8 mg/kg), rising from 45 +/- 7 to 81 +/- 18 ng/l. These results suggest that acetaldehyde is the active component in the chlorpropamide + ethanol-induced MLI secretion. Plasma MLI was also measured following acetaldehyde infusion in adrenalectomized dogs with and without hexamethonium treatment. Acute bilateral adrenalectomy resulted in a decrease (P less than 0.05) in plasma MLI concentrations, but the levels remained detectable. Moreover, subsequent acetaldehyde infusion led to rises in plasma MLI similar to those observed in animals with intact adrenals. These MLI responses were not altered by the concurrent i.v. administration of hexamethonium.(ABSTRACT TRUNCATED AT 250 WORDS)

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Plasma levels and biochemical characterisation of circulating met-enkephalin in canine endotoxin shock

Cited by 32 publications

References 24 publications

-Endorphin and met-enkephalin in plasma of cattle during pregnancy, parturition and the neonatal period

-Endorphin and met-enkephalin in plasma of cattle during pregnancy, parturition and the neonatal period

Adrenal vein and arterial levels of catecholamines and immunoreactive metenkephalin in canine endotoxin shock and their response to naloxone

Effects of ethanol and inhibitors of its metabolism on the circulating levels of Met-enkephalin in greyhounds

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