Changes in catecholaminergic pathways innervating the rat heart ventricle during morphine dependence. Involvement Of alpha(1)- and alpha(2)-adrenoceptors

Takotsubo cardiomyopathy in children

OBJECTIVE

To explore the epidemiology and outcomes of takotsubo cardiomyopathy in children.

METHODS

A retrospective analysis of the Healthcare Cost and Utilization 2012 and 2016 Kids' Inpatient Database was performed. Patients admitted with the diagnosis of takotsubo cardiomyopathy in the age group of 1 month-20 years were identified using International Classification of Diseases (ICD)-9 code 429.83 and ICD-10 code I51.81.

RESULTS

Among a total of 4,860,859 discharges, there were 153 with the diagnosis of takotsubo cardiomyopathy (3.1 per 100,000 discharges). Among patients with takotsubo cardiomyopathy, 55.0% were male, 62.4% were white, and 16.7% were black. Eighty-nine percent of patients were between 12 and 20 years. Psychiatric diagnosis was documented in 46% and substance use disorder in 36.2%. Sepsis was documented in 22.8% of patients. The median length of stay was 5 days (interquartile range: 2.7-15), and median total charges were $75,080 (interquartile range: 32,176-198,336). The overall mortality for takotsubo cardiomyopathy was 7%. On multivariable regression analysis, mortality was higher in the presence of anoxic injury (odds ratio = 34.42, 95% confidence interval: 4.85-320.11, p = 0.00).

CONCLUSIONS

Takotsubo cardiomyopathy is uncommon in children and carries a mortality rate of 7%. Most children with takotsubo cardiomyopathy are adolescent males, many of whom have psychiatric disorder or substance use disorder or both. Takotsubo cardiomyopathy should be considered in the differential diagnosis for patients who present with cardiac dysfunction and have underlying psychiatric disorders or drug abuse.

Takotsubo Cardiomyopathy precipitated by opiate withdrawal

INTRODUCTION

Takotsubo Cardiomyopathy is a transient non-ischemic cardiomyopathy usually characterized by apical ballooning of the left ventricle, with electrocardiographic changes and enzyme release, without evidence of obstructive coronary artery disease. Typically seen in stress induced situations, in post-menopausal females, this condition may have a predilection for patients with dependency disorders.

CASE

The following is a case in which Takotsubo Cardiomyopathy was induced by withdrawal from opiate medications. Followed by resolution of symptoms after restarting maintenance opioid therapy.

DISCUSSION

We feel health care professionals should be aware of this possibility in such a patient population especially when they have demonstrated cardiovascular symptomatology. Given the prevalence of opiate use both recreational and iatrogenic, the index of suspicion for opiate-withdrawal induced cardiomyopathy should be high in the presence of cardiac symptomatology.

The effects of serotonin/norepinephrine reuptake inhibitors and serotonin receptor agonist on morphine analgesia and tolerance in rats

Several studies have demonstrated that serotonergic and noradrenergic systems have important roles in morphine analgesia and tolerance. However, the exact mechanism underlying the development of morphine tolerance is not fully understood. The aim of this study was to investigate the possible role of serotonin/norepinephrine reuptake inhibitors (amitriptyline, venlafaxine) and serotonin receptor (5-HT(1A) and 5-HT(1B/1D)) agonist (dihydroergotamine) in morphine analgesia and tolerance in rats. To constitute morphine tolerance, animals received morphine (50 mg/kg; s.c.) once daily for 3 days. After the last dose of morphine was injected on day 4, morphine tolerance was evaluated. The analgesic effects of amitriptyline (20 mg/kg; i.p.), venlafaxine (20 mg/kg; s.c.), dihydroergotamine (100 μg/kg; i.v.) and morphine (5 mg/kg) were considered at 15- to 30-min intervals (0, 15, 30, 60, 90, and 120 min) by tail-flick and hot-plate analgesia tests. In this study, the data obtained suggested that amitriptyline and venlafaxine significantly increased the analgesic effect of morphine and attenuated the expression of morphine tolerance. However, dihydroergotamine significantly increased the analgesic effect of morphine but did not reduce the expression of morphine tolerance. In conclusion, we determined that co-administration of morphine with amitriptyline and venlafaxine increased the analgesic effects of morphine and attenuated the morphine analgesic tolerance.

Effects of alpha 2-adrenoceptor agonists dexmedetomidine and guanfacine on morphine analgesia and tolerance in rats

BACKGROUND

Alpha 2 (α(2))-adrenoceptor agonists may be useful for their potential to increase or prolong opioid analgesia while attenuating the development of opioid tolerance. The purpose of this study was to investigate the effects of dexmedetomidine and guanfacine (α(2)-adrenoceptor agonists) on morphine analgesia and tolerance in rats.

METHODS

Adult male Wistar albino rats weighing 195-205 g were used. To constitute morphine tolerance, animals received morphine (50 mg/kg) once daily for 3 days. After the last dose of morphine had been injected on day 4, morphine tolerance was evaluated by analgesia tests. The analgesic effects of dexmedetomidine (20 ug/kg), guanfacine (0.5 mg/kg), MK-467 (0.25 mg/kg), and morphine were estimated at 30-min intervals (0, 30, 60, 90, and 120 min) by tail-flick and hot-plate analgesia tests.

RESULTS

Our findings indicate that dexmedetomidine and guanfacine attenuated the expression of morphine tolerance. In addition, administration of dexmedetomidine with morphine increased morphine analgesia. On the contrary, data suggested that MK-467 (an α(2)-adrenoceptor antagonist) decreased morphine analgesia and increased morphine tolerance in analgesia tests.

CONCLUSION

In conclusion, we observed that co-injection of dexmedetomidine or guanfacine with morphine attenuated the expression of tolerance to the analgesic effect of morphine and that dexmedetomidine enhanced the morphine analgesia.

Effects of a Rhodiola rosea L. extract on acquisition and expression of morphine tolerance and dependence in mice

This study investigated the effect of Rhodiola rosea L. extract on acquisition and expression of morphine tolerance and dependence in mice. Therefore animals were injected with repeated administration of morphine (10 mg/kg, subcutaneous) twice daily for five or six days, in order to make them tolerant or dependent. Rhodiola rosea L. extract (0, 10, 15 and 20 mg/kg) was administered by the intragastric route 60 min prior to each morphine injection (for acquisition) or prior the last injection of morphine or naloxone on test day (for tolerance or dependence expression, respectively). Morphine tolerance was evaluated by testing its analgesic effect in the tail flick test at the 1st and 5th days. Morphine dependence was evaluated by counting the number of withdrawal signs (jumping, rearing, forepaw tremor, teeth chatter) after naloxone injection (5 mg/kg; intraperitoneal) on the test day (day 6). Results showed that Rhodiola rosea L. extract significantly reduced the expression of morphine tolerance, while it was ineffective in modulating its acquisition. Conversely, Rhodiola rosea L. extract significantly and dose-dependently attenuated both development and expression of morphine dependence after chronic or acute administration. These data suggest that Rhodiola rosea L. may have human therapeutic potential for treatment of opioid addiction.

The PKs PKA and ERK 1/2 are involved in phosphorylation of TH at Serine 40 and 31 during morphine withdrawal in rat hearts

BACKGROUND AND PURPOSE

Our previous studies have shown that morphine withdrawal induced hyperactivity of cardiac noradrenergic pathways. The purpose of the present study was to evaluate the effects of morphine withdrawal on site-specific phosphorylation of TH in the heart.

EXPERIMENTAL APPROACH

Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets in rats. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (2 mg kg(-1)). TH phosphorylation was determined by quantitative blot immunolabelling using phosphorylation state-specific antibodies.

KEY RESULTS

Naloxone-induced morphine withdrawal induced phosphorylation of TH at serine (Ser)40 and Ser31 in the right ventricle, associated with both an increase in total TH levels and an enhancement of TH activity. When HA-1004 (PK A inhibitor) was infused, concomitantly with morphine, it diminished the increase in noradrenaline turnover, total TH levels and TH phosphorylation at Ser40 in morphine-withdrawn rats. In contrast, the infusion of calphostin C (PKC inhibitor), did not modify the morphine withdrawal-induced increase in noradrenaline turnover and total TH levels. In addition, we show that the ability of morphine withdrawal to stimulate phosphorylation at Ser31 was reduced by SL327, an inhibitor of ERK 1/2 activation.

CONCLUSIONS AND IMPLICATIONS

The present findings demonstrate that the enhancement of total TH levels and the increased phosphorylation state of TH during morphine withdrawal were dependent on PKA and ERK activities and suggest that these transduction pathways might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine withdrawal.

Phosphodiesterase 4 inhibitors, rolipram and diazepam block the adaptive changes observed during morphine withdrawal in the heart

In this study, we investigated whether morphine dependence was inhibited by phosphodiesterase (PDE) 4 inhibitors rolipram and diazepam, since a role for the cyclic AMP systems in the development of morphine dependence was reported. Dependence of morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone. In order to determine the effect of rolipram or diazepam the animals were injected with these drugs for seven days and 30 min before the administration of naloxone. When opioid withdrawal was precipitated, enhancement of noradrenaline (NA) turnover in the heart was observed 30 min after naloxone administration. Moreover, morphine withdrawal induces Fos expression, increase in cyclic AMP and cyclic GMP levels. Co-administration of rolipram or diazepam with morphine during the pre-treatment period significantly reduces the signs of withdrawal symptoms, the enhancement of NA turnover, the increase in cyclic AMP and the Fos expression. However, these inhibitors did not modify the levels of cyclic GMP. These findings demonstrated that co-administration of rolipram or diazepam with morphine abolish the development of morphine dependence and suggest that these compounds prevent the up-regulation of the cyclic AMP pathway and the associated increase in cyclic AMP level after naloxone administration.

Activation of the ERK signalling pathway contributes to the adaptive changes in rat hearts during naloxone-induced morphine withdrawal

BACKGROUND AND PURPOSE

We have previously demonstrated that morphine withdrawal induced hyperactivity of the heart by activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline turnover and c-Fos expression. The extracellular signal-regulated kinase (ERK) has been implicated in drug addiction, but its role in activation of the heart during morphine dependence remains poorly understood. Here, we have looked for activation of ERK during morphine withdrawal and if this activation induced gene expression.

EXPERIMENTAL APPROACH

Dependence on morphine was induced by s.c. implantation of morphine pellets for 7 days. Morphine withdrawal was precipitated on day 8 by injection of naloxone (2 mg kg(-1), s.c.). ERK1/2, their phosphorylated forms and c-Fos were measured by western blotting and immunohistochemistry of cardiac tissue.

KEY RESULTS

Naloxone-induced morphine withdrawal activated ERK1/2 and increased c-Fos expression in cardiac tissues. c-Fos expression was blocked by SL327, a drug that prevents ERK activation.

CONCLUSIONS AND IMPLICATIONS

These results indicate that signalling through the ERKs is necessary for morphine withdrawal-induced hyperactivity of the heart and suggest that this pathway may also be involved in activation of immediate-early genes in both cytosolic and nuclear effector mechanisms that have the potential to bring about long-term changes in the heart.

Differential involvement of 3′, 5′-cyclic adenosine monophosphate-dependent protein kinase in regulation of Fos and tyrosine hydroxylase expression in the heart after naloxone induced morphine withdrawal

We previously demonstrated that morphine withdrawal induced hyperactivity of the heart by the activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline (NA) turnover and Fos expression. We investigated whether cAMP-dependent protein kinase (PKA) plays a role in this process by estimating changes in PKA immunoreactivity and the influence of inhibitor of PKA on Fos protein expression, tyrosine hydroxylase (TH) immunoreactivity levels and NA turnover in the left and right ventricle. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (5 mg/kg). When opioid withdrawal was precipitated, an increase in PKA immunoreactivity and phospho-CREB (cyclic AMP response element protein) levels were observed in the heart. Moreover, morphine withdrawal induces Fos expression, an enhancement of NA turnover and an increase in the total TH levels. When the selective PKA inhibitor HA-1004 was infused, concomitantly with morphine pellets, it diminished the increase in NA turnover and the total TH levels observed in morphine-withdrawn rats. However, this inhibitor neither modifies the morphine withdrawal induced Fos expression nor the increase of nonphosphorylated TH levels. The present findings indicate that an up-regulated PKA-dependent transduction pathway might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine withdrawal and suggest that Fos is not a target of PKA at heart levels.

Role of PKC in regulation of Fos and TH expression after naloxone induced morphine withdrawal in the heart

We previously demonstrated that morphine withdrawal induced hyperactivity of the heart by activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline (NA) turnover and Fos expression. The present study was designed to investigate the role of protein kinase C (PKC) in this process, by estimating whether pharmacological inhibition of PKC would attenuate morphine withdrawal induced Fos expression and changes in tyrosine hydroxylase (TH) immunoreactivity levels and NA turnover in the left and right ventricle. Dependence on morphine was induced on day 8 by an injection of naloxone. Morphine withdrawal induced Fos expression and increased TH levels and NA turnover in the right and left ventricle. Infusion of calphostin C, a selective PKC inhibitor, did not modify the morphine withdrawal-induced increase in NA turnover and TH levels. However, this inhibitor produced a reduction in the morphine withdrawal-induced Fos expression. The results of the present study provide new information on the mechanisms that underlie morphine withdrawal-induced up-regulation of Fos expression in the heart and suggest that TH is not a target of PKC during morphine withdrawal at heart levels.

Alterations in protein kinase A and different protein kinase C isoforms in the heart during morphine withdrawal

The present study was designed to investigate the possible changes of protein kinase A (PKA) and different isoforms of protein kinase C (PKC): PKC alpha, PKC delta and PKC zeta after naloxone induced morphine withdrawal in the heart. Male rats were implanted with placebo (naïve) or morphine (tolerant/dependent) pellets for 7 days. On day 8 rats received saline s.c. or naloxone (5 mg/kg s.c.). The protein levels of PKA, PKC delta and PKC zeta were significantly up-regulated in the heart from morphine withdrawal rats. By contrast, morphine withdrawal induced down-regulation of PKC alpha. These results suggest that both PKA and PKC may be involved in the cardiac adaptive changes observed during morphine withdrawal.

Increase of tyrosine hydroxylase levels and activity during morphine withdrawal in the heart

Our previous studies have shown an enhanced activity of the noradrenergic pathways innervating the heart in rats withdrawn from morphine. However, the possible adaptive changes that can occur in these pathways during morphine dependence are not known. We studied the alterations in tyrosine hydroxylase (the rate-limiting enzyme in catecholamines biosynthesis) and tyrosine hydroxylase activity in the heart (right and left ventricle) during morphine withdrawal. In the same paradigm, we measured Fos expression as a marker of neuronal activation and the normetanephrine/noradrenaline ratio (an index of noradrenaline turnover). We evaluated the levels of tyrosine hydroxylase and Fos by quantitative Western blot analysis, and noradrenaline turnover using high-performance liquid chromatography (HPLC). Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (5 mg/kg s.c.). The results show a significant increase in tyrosine hydroxylase levels and activity in the right and left ventricle 30 or 90 min after naloxone precipitated withdrawal in parallel with an increase in noradrenaline turnover. Morphine withdrawal also induced an increase in the Fos expression, which indicates an activation of cardiac cellular activity. Our results suggest that an increase in tyrosine hydroxylase protein levels and tyrosine hydroxylase enzyme activity might contribute to the enhanced noradrenergic activity in the heart in response to morphine withdrawal.

Morphine withdrawal-induced c-fos expression in the heart: a peripheral mechanism

We previously demonstrated that hyperactivity of cardiac noradrenergic pathways observed during morphine withdrawal is mediated by peripheral mechanisms. In the present study, naloxone methiodide (quaternary derivative of naloxone that does not cross the blood-brain barrier) and naloxone were administered to morphine-dependent rats and Fos immunostaining was used as a reflection of neuronal activity. Dependence on morphine was induced by 7-day chronic subcutaneous (s.c.) implantation of six morphine pellets (75 mg). Morphine withdrawal was precipitated by administration of naloxone methiodide (5 mg/kg, s.c.) or naloxone (5 mg/kg, s.c.) on day 8. Using immunohistochemical staining of Fos, present results indicate that the administration of naloxone methiodide or naloxone to morphine-dependent rats induced marked Fos immunoreactivity within the cardiomyocyte nuclei. Moreover, Western blot analysis revealed a peak expression of c-fos in the right and left ventricles after naloxone methiodide- or naloxone-precipitated withdrawal. In addition, in the hypothalamic paraventricular nucleus (PVN), Fos expression was increased after naloxone-but not after naloxone methiodide-administration to morphine-dependent rats. These results suggest that the activation of c-fos expression observed during morphine withdrawal in the heart is due to intrinsic mechanisms outside the central nervous system (CNS).

Activation of c-fos expression in the heart after morphine but not U-50,488H withdrawal

1. In the present work we have studied in the heart the expression of Fos, the protein product of the c-fos proto-oncogene and the adaptive changes in noradrenergic neurons after naloxone or nor-binaltorphimine (nor-BNI) administration to morphine or U-50,488H pretreated rats. 2. Male rats were implanted with placebo (naïve) or morphine (tolerant/dependent) pellets for 7 days. On day 8 rats received saline s.c., naloxone (5 mg kg(-1) s.c.) or nor-BNI (5 mg kg(-1) i.p.). Other groups of rats were rendered tolerant/dependent on U-50,488H by injecting the drug twice daily (15 mg kg(-1) i.p.) for 4 days. Control animals received saline. On day 5 the animals were injected with vehicle i.p. or nor-BNI (5 mg kg(-1) i.p.). 3. Using immunohistochemical staining of Fos, present results indicate that morphine withdrawal induced marked Fos immunoreactivity (Fos-IR) within the cardiomyocyte nuclei. Moreover, Western blots analysis revealed a peak expression of c-fos in right and left ventricle after naloxone induced withdrawal in parallel with an increase in noradrenaline (NA) turnover. 4. However, after nor-BNI administration to rats chronically treated with U-50,488H, we found a decrease in the NA turnover. In addition, the administration of nor-BNI to rats chronically treated with U-50,488H or morphine did not induce modifications in the Fos-IR, in the heart. 5. These results demonstrated that morphine withdrawal induces the expression of Fos protein, as well as an enhancement of noradrenergic activity in the heart. In contrast to morphine U-50,488 withdrawal produces no changes in Fos-IR in parallel with a decrease in NA turnover, indicating that the kappa-opioid receptors are not involved in the molecular adaptive mechanisms responsible for the development of opioid dependence in the heart.

Influence of prazosin and clonidine on morphine analgesia, tolerance and withdrawal in mice

Rapid development of tolerance and dependence limits the usefulness of morphine in long-term treatment. We examined the effects of clonidine (alpha(2)-adrenoceptor agonist) and prazosin (alpha(1)-adrenoceptor antagonist) on morphine analgesia, tolerance and withdrawal. Morphine tolerance was induced using a 3-day cumulative twice-daily dosing regimen with s.c. doses up to 120 mg/kg. Tolerance was assessed on day 4, as loss of the antinociceptive effect of a test dose of morphine (5 mg/kg). After 10 h, morphine withdrawal was precipitated with naloxone (1 mg/kg). Prazosin had no analgesic effect alone but dose-dependently potentiated morphine analgesia in morphine-naive mice. Another alpha(1)-adrenoceptor antagonist, corynanthine, had similar effects. Prazosin also increased the analgesic potency of the morphine test dose in morphine-tolerant mice. Naloxone-precipitated vertical jumping was not affected, but weight loss was reduced by prazosin. Acutely administered clonidine potentiated morphine analgesia and alleviated opioid withdrawal signs, as expected. We conclude that in addition to the already established involvement of alpha(2)-adrenoceptors in opioid actions, also alpha(1)-adrenoceptors have significant modulatory role in opioid analgesia and withdrawal.