Dexmedetomidine, an α2 agonist, increases the morphine analgesic effect and decreases morphine tolerance development by suppressing oxidative stress and TNF/IL-1 signalling pathway in rats

BACKGROUND

The aim of the present study is to examine the possible effect de dexmedetomidine on the development of morphine tolerance in rats including nociception, morphine analgesia, apoptosis, oxidative stress, and tumour necrosis factor (TNF)/ interleukin-1 (IL-1) pathways.

MATERIALS AND METHODS

In this study, 36 Wistar Albino (225-245 g) rats were used. Animals were divided into 6 groups: saline (S), 20 mcg/kg dexmedetomidine (D), 5 mg/kg morphine (M), M + D, morphine tolerance (MT), and MT + D. The analgesic effect was measured with hot plate and tail-flick analgesia tests. After the analgesia tests, the dorsal root ganglia (DRG) tissues were excised. Oxidative stress parameters [total antioxidant status (TAS), total oxidant status (TOS)], TNF, IL-1 and apoptosis enzymes (Caspase-3, Caspase-9), were measured in DRG tissues.

RESULTS

Dexmedetomidine showed an antinociceptive effect when given alone (p < 0.05 to p < 0.001). In addition, dexmedetomidine increased the analgesic effect of morphine (p < 0.001), and also decreased the tolerance to morphine at a significant level (p < 0.01 to p < 0.001). Moreover, it decreased oxidative stress (p < 0.001) and TNF/IL-1 levels when given as an additional drug of single-dose morphine and morphine tolerance group (p < 0.001). Furthermore, dexmedetomidine decreased Caspase-3 and Caspase-9 levels after tolerance development (p < 0.001).

CONCLUSION

Dexmedetomidine has antinociceptive properties, and it increases the analgesic effect of morphine and also prevents tolerance development. These effects probably occur by the modulation of oxidative stress, inflammation and apoptosis.

Serum caspase-3 levels during the first week of traumatic brain injury

OBJECTIVE

Confluence between the intrinsic and extrinsic apoptosis pathways is reached at the point of caspase-3 activation, which induces death cell. Higher serum caspase-3 levels have been recorded on day 1 of traumatic brain injury (TBI) in 30-day non-survivors compared to survivors. The objectives of this study therefore were to determine whether serum caspase-3 levels are persistently higher in non-survivors than in survivors, and whether these levels may be used to predict 30-day mortality.

DESIGN

A prospective observational study was carried out.

SETTING

Six Spanish Intensive Care Units.

PATIENTS

Patients with severe isolated TBI (defined as Glasgow Coma Scale <9 points and non-cranial Injury Severity Score <10 points).

INTERVENTIONS

Serum caspase-3 concentrations were measured on days 1, 4 and 8 of TBI.

MAIN VARIABLES OF INTEREST

Thirty-day mortality was considered as the study endpoint.

RESULTS

In comparison with non-survivors (n=34), 30-day survivors (n=90) showed lower serum caspase-3 levels on days 1 (p=0.001), 4 (p<0.001) and 8 (p<0.001) of TBI. Analysis of the ROC curves showed serum caspase-3 concentrations on days 1, 4 and 8 of TBI to have an AUC (95% CI) in predicting 30-day mortality of 0.70 (0.61-0.78; p=0.001), 0.83 (0.74-0.89; p<0.001) and 0.87 (0.79-0.93; p<0.001), respectively.

CONCLUSIONS

The novel findings of our study were that serum caspase-3 levels during the first week of TBI were lower in survivors and could predict 30-day mortality.

Biological implications of selenium in adolescent rats exposed to binge drinking: Oxidative, immunologic and apoptotic balance

Alcohol intermittent binge drinking (BD) during adolescence decreases the levels of selenium (Se), a trace element that plays a key biological role against oxidative damage in hepatocytes through different selenoproteins such as the antioxidant enzymes glutathione peroxidases (GPx1 and Gpx4) and selenoprotein P (SelP). In this context, it has been found that GPx4 has an essential antioxidant role in mitochondria modulating the apoptosis and NF-kB activation (a factor intimately related to apoptosis and immune function). To further investigate the effectiveness of selenium supplementation in oxidative balance, inflammation and apoptosis, the present study examined the protective effects of 0.4ppm of dietary selenite administrated to adolescent rats exposed to BD. BD consumption depleted Se deposits in all the tissues studied. In liver, GPx1 activity and expression were decreased leading to protein and lipid hepatic oxidation. Moreover GPx4 and NF-kB expression were also decreased in liver, coinciding with an increase in caspase-3 expression. This hepatic profile caused general liver damage as shown the increased serum transaminases ratio AST/ALT. Proinflammatory serum citokines and chemocines were decreased. Se supplementation therapy used restored all these values, even AST levels. These findings suggest for first time that Se supplementation is a good strategy against BD liver damage during adolescence, since it increases GPx1 and GPx4 expression and avoids NF-kB downregulation and caspase-3 upregulation, leading to a better oxidative, inflammatory and apoptotic liver profile. The therapy proposed could be considered to have a great biological efficacy and to be suitable for BD exposed teenagers in order to avoid future hepatic complications.

Cellular changes in motor neuron cell culture produced by cytotoxic cerebrospinal fluid from patients with amyotrophic lateral sclerosis

INTRODUCTION

The neurotoxic effects of cerebrospinal fluid (CSF) from patients with amyotrophic lateral sclerosis (ALS) have been reported by various authors who have attributed this neurotoxicity to the glutamate in CSF-ALS.

MATERIAL AND METHODS

Cultures of rat embryonic cortical neurons were exposed to CSF from ALS patients during an incubation period of 24 hours. Optical microscopy was used to compare cellular changes to those elicited by exposure to 100μm glutamate, and confocal microscopy was used to evaluate immunohistochemistry for caspase-3, TNFα, and peripherin.

RESULTS

In the culture exposed to CSF-ALS, we observed cells with nuclear fragmentation and scarce or null structural modifications to the cytoplasmic organelles or to plasma membrane maintenance. This did not occur in the culture exposed to glutamate. The culture exposed to CSF-ALS also demonstrated increases in caspase-3, TNFα, and in peripherin co-locating with caspase-3, but not with TNFα, suggesting that TNFα may play an early role in the process of apoptosis.

CONCLUSIONS

CFS-ALS cytotoxicity is not related to glutamate. It initially affects the nucleus without altering the cytoplasmic membrane. It causes cytoplasmic apoptosis that involves an increase in caspase-3 co-located with peripherin, which is also overexpressed.