Reason for the aggravation of diseases caused by inflammation and the ineffectiveness of NSAIDs on these diseases in rainy weather

The relation between the effect of a subhypnotic dose of thiopental on claw pain threshold in rats and adrenalin, noradrenalin and dopamine levels

Thiopental sodium (TPS) needs to be applied together with adrenalin in order to establish its analgesic effect in general anesthesia. We aimed to investigate the effect of TPS on the claw pain threshold in rats and evaluated its relationship with endogenous adrenalin (ADR), noradrenalin (NDR), and dopamine (DOP) levels. Intact and adrenalectomized rats were used in the experiment. Intact animals were divided into the following groups: 15 mg/kg TPS (TS), 0.3 mg/kg ADR+15 mg/kg TPS (ATS) and 0.3 mg/kg ADR alone (ADR). Adrenalectomized animals were divided into the following groups: 15 mg/kg TPS (A-TS), 0.3 mg/kg ADR+15 mg/kg TPS (A-ATS) and 0.3 mg/kg ADR alone (A-ADR). Claw pain threshold and blood ADR, NDR, and DOP levels were measured. The TS group’s claw pain threshold was found low. However, the claw pain thresholds of the ATS and ADR groups increased significantly. In the A-TS group, the pain threshold decreased compared with normal, and in the A-ATS and A-ADR groups, the pain threshold increased. TPS reduced the blood ADR levels in intact rats; however, no significant changes were observed in the NDR and DOP levels. #TPS provides hyperalgesia by reducing the production of ADR in rats. The present study shows that to achieve analgesic activity, TPS needs to be applied together with ADR.

Anti-inflammatory and antinociceptive effects of salbutamol on acute and chronic models of inflammation in rats: involvement of an antioxidant mechanism

The possible role of β-2 adrenergic receptors in modulation of inflammatory and nociceptive conditions suggests that the β-2 adrenergic receptor agonist, salbutamol, may have beneficial anti-inflammatory and analgesic effects. Therefore, in this study, we induced inflammatory and nociceptive responses with carrageenan-induced paw edema or cotton-pellet-induced granuloma models, both of which result in oxidative stress. We hypothesized that salbutamol would prevent inflammatory and nociceptive responses by stimulating β-2 adrenergic receptors and the prevention of generation of ROS during the acute inflammation process in rats. Both doses of salbutamol used in the study (1 and 2 mg/kg) effectively blocked the acute inflammation and inflammatory nociception induced by carrageenan. In the cotton-pellet-induced granuloma test, both doses of salbutamol also significantly decreased the weight of granuloma tissue on the cotton pellets when compared to the control. Anti-inflammatory and analgesic effects of salbutamol were found to be comparable with those of indomethacin. Salbutamol decreased myeloperoxidase (MPO) activity and lipid peroxidation (LPO) level and increased the activity of superoxide dismutase (SOD) and level of glutathione (GSH) during the acute phase of inflammation. In conclusion, salbutamol can decrease acute and chronic inflammation, possibly through the stimulation of β-2 adrenergic receptors. This anti-inflammatory effect may be of significance in asthma treatment, where inflammation also takes part in the etiopathology. This study reveals that salbutamol has significant antioxidative effects, which at least partially explain its anti-inflammatory capabilities. These findings presented here may also shed light on the roles of β-2 adrenergic receptors in inflammatory and hyperalgesic conditions.

Effects of epinephrine and cortisol on the analgesic activity of metyrosine in rats

Some endogenous hormones (epinephrine and cortisol) can change an individual's pain threshold. Propranolol is a non-selective β adrenergic receptor blocker which antagonises the anti-inflammatory effect of non-steroidal anti-inflammatory drugs via the β1 and β2 adrenergic receptors. The roles of epinephrine and cortisol were investigated in the analgesic activity of metyrosine in rats with reduced epinephrine levels induced by metyrosine. Pain threshold measurement was performed using an analgesimeter with different doses and the single or combined usage of metyrosine, prednisolone, metyrapone and propranolol in rats. Epinephrine and corticosterone levels were measured by high-performance liquid chromatography in metyrosineadministered rats. Metyrosine reduces the epinephrine levels without affecting the corticosterone levels, thereby creating an analgesic effect. It was determined that prednisolone did not have an analgesic effect in rats with normal epinephrine levels, but its analgesic activity increased with a parallel decrease in the epinephrine levels. Similarly, the combined use of prednisolone and metyrosine provided a stronger analgesic effect than that rendered by metyrosine alone. The strongest analgesic effect, however, was observed in the group of rats with the lowest epinephrine level in whom the metyrosine + prednisolone combination was administered. The findings of this study may be useful in severe pain cases in which the available analgesics are unable to relieve the individual's pain.

Role of adrenal gland hormones in the anti-inflammatory effect mechanism of tamoxifen, a partial antagonist for oestrogen receptors, and relation with COX levels

OBJECTIVE

There is limited study about anti-inflammatory effect mechanism of tamoxifen. We aimed to investigate the anti-inflammatory activity of tamoxifen to see whether adrenal gland hormones have roles in the anti-inflammatory effect mechanism of tamoxifen and to evaluate the relationship between anti-inflammatory activity and cyclooxygenase (COX) level.

STUDY DESIGN

Effects of tamoxifen, indomethacin and prednisolon on carrageenan-induced inflammatory paw oedema were investigated in intact and adrenalectomised rats. Also blood adrenalin and corticosterone levels and paw tissue COX levels determined biochemically.

RESULTS

Tamoxifen (5, 10 and 20 mg/kg), indomethacin (5, 10 and 20 mg/kg) and prednisolon (5 mg/kg) produced anti-inflammatory effects in intact rats, however, they could not in adrenalectomized rats. 20 mg/kg tamoxifen produced low anti-inflammatory effect. Tamoxifen and indomethacin decreased COX-2 levels in intact rats, but not in adrenalectomised rats. Tamoxifen produced anti-inflammatory effects by decreasing adrenalin levels, as indomethacin does. 20 mg/kg tamoxifen decreased corticosterone levels.

CONCLUSIONS

Tamoxifen was seen to suppress carrageenan-induced inflammation significantly. The dose of tamoxifen that decreases adrenalin levels maximally and decreases corticosterone levels minimally was found to produce the most potent anti-inflammatory effect. The reason why indomethacin is more potent in high doses may be that it decreases adrenalin levels strongly at these doses, without decreasing corticosterone levels.

Indirect role of beta2-adrenergic receptors in the mechanism of analgesic action of nonsteroidal antiinflammatory drugs

OBJECTIVE

Adrenal gland hormones have been shown to have a role in the antiinflammatory effect mechanism of nonsteroidal antiinflammatory drugs. This study investigates whether the analgesic effects of indomethacin, diclofenac sodium, aspirin, and nimesulide (IDAN; upper case letters of the four drugs we used) are also related to adrenal gland hormones.

DESIGN

The analgesic effects of IDAN were studied in the carrageenan-induced inflammatory pain model using both intact and adrenalectomized rats. Paw withdrawal tests were performed in adrenalectomized rats that had been pretreated with phenoxybenzamine, propranolol, and metoprolol.

SETTING

This study was performed in Pharmacology and Biochemistry Laboratories of Faculty of Medicine.

PATIENTS/SUBJECTS

A total of 306 (114 intact and 192 adrenalectomized) male Albino Wistar rats were used.

INTERVENTIONS

Adrernalectomy, drug administrations, pain model induction and pain threshold measurements were performed during the study.

MEASUREMENTS AND MAIN RESULTS

Although the analgesic effects of nonsteroidal antiinflammatory drugs were lost in adrenalectomized rats, they exerted significant analgesia in adrenalectomized rats that had been pretreated with prednisolone and adrenalin. All these drugs were found to decrease serum adrenalin concentration but did not change serum cortisole (corticosterone in rats) concentration. Prednisolone and adrenalin inhibited carrageenan-induced hyperalgesia in adrenalectomized rat groups pretreated with metoprolol or phenoxybenzamine, but not in rats given propranolol. Propranolol also negated the analgesic effects of IDAN in intact rats. The analgesic effects provided by either prednisolone or adrenalin could not be inhibited by the alpha1, alpha2, or beta1 blockers but disappeared when beta2 receptors were blocked.

CONCLUSIONS

The analgesic effects of nonsteroidal antiinflammatory drugs appear to be related to endogenous adrenalin and cortisole. We have demonstrated that adrenalin and prednisolone play important roles in the analgesic effect mechanism of IDAN. Prednisolone and adrenalin produce analgesic effects through beta2-adrenergic receptors, suggesting an indirect role for beta2-adrenergic receptors in the analgesic effect mechanism of the nonsteroidal antiinflammatory drugs mentioned.

Gastric anti-ulcerative and anti-inflammatory activity of metyrosine in rats

In this study, the anti-inflammatory and anti-ulcerative effects of metyrosine, a selective tyrosine hydroxylase enzyme inhibitor, were investigated in rats. For ulcer experiments, indomethacin-induced gastric ulcer tests and ethanol-induced gastric ulcer tests were used. For these experiments, rats were fasted for 24 h. Different doses of metyrosine and 25 mg/kg doses of ranitidine were administered to rats, followed by indomethacin at 25 mg/kg for the indomethacin-induced ulcer test, or 50% ethanol for the ethanol-induced test. Results have shown that at all of the doses used (50, 100 and 200 mg/kg), metyrosine had significant anti-ulcerative effects in both indomethacin and ethanol-induced ulcer tests. Metyrosine doses of 100 and 200 mg/kg (especially the 200 mg/kg dose) also inhibited carrageenan-induced paw inflammation even more effectively than indomethacin. In addition, to characterize the anti-inflammatory mechanism of metyrosine we investigated its effects on cyclooxygenase (COX) activity in inflammatory tissue (rat paw). The results showed that all doses of metyrosine significantly inhibited high COX-2 activity. The degree of COX-2 inhibition correlated with the increase in anti-inflammatory activity. In conclusion, we found that metyrosine has more anti-inflammatory effects than indomethacin and that these effects can be attributed to the selective inhibition of COX-2 enzymes by metyrosine. We also found that adrenalin levels are reduced upon metyrosine treatment, which may be the cause of the observed gastro-protective effects of this compound.

Occurrence of anticancer activity of prednisolone via adrenalectomy and inhibition of adrenaline in rats

In this study, the anticancer effect of prednisolone was investigated using rats with normal endogen adrenaline levels (intact), reduced adrenaline levels (metyrosine-induced) and adrenaline deficiency (adrenalectomized) via gastric adenocarcinoma model. Gastric adenocarcinoma was induced with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). According to our experimental results, prednisolone could not prevent MNNG-induced adenocarcinoma when used alone in intact rats. There were neither macroscopic nor microscopic signs of cancer in the rat groups that received metyrosine and prednisolone. However, dysplasia occurred in the stomachs of 2 of 10 rats that received metyrosine and prednisolone. There was no adenocarcinoma genesis in the stomachs of adrenalectomized rats that received prednisolone alone. However, yohimbine (a selective blocker of alpha2-adrenoreceptors) pretreatment in adrenalectomized rats negated the anticancer effect of prednisolone. In conclusion, prednisolone was shown not to be an anticancer agent in intact rats when used alone; however, it has anticancer effects in rats whose adrenaline levels were reduced via adrenalectomy or metyrosine, which is a catecholamine synthesis inhibitor.