Chronic morphine induces up-regulation of the pro-apoptotic Fas receptor and down-regulation of the anti-apoptotic Bcl-2 oncoprotein in rat brain

Evaluating the daily modulation of FADD and related molecular markers in different brain regions in male rats

Fas-Associated protein with Death Domain (FADD), a key molecule controlling cell fate by balancing apoptotic versus non-apoptotic functions, is dysregulated in post-mortem brains of subjects with psychopathologies, in animal models capturing certain aspects of these disorders, and by several pharmacological agents. Since persistent disruptions in normal functioning of daily rhythms are linked with these conditions, oscillations over time of key biomarkers, such as FADD, could play a crucial role in balancing the clinical outcome. Therefore, we characterized the 24-h regulation of FADD (and linked molecular partners: p-ERK/t-ERK ratio, Cdk-5, p35/p25, cell proliferation) in key brain regions for FADD regulation (prefrontal cortex, striatum, hippocampus). Samples were collected during Zeitgeber time (ZT) 2, ZT5, ZT8, ZT11, ZT14, ZT17, ZT20, and ZT23 (ZT0, lights-on or inactive period; ZT12, lights-off or active period). FADD showed similar daily fluctuations in all regions analyzed, with higher values during lights off, and opposite to p-ERK/t-ERK ratios regulation. Both Cdk-5 and p35 remained stable and did not change across ZT. However, p25 increased during lights off, but exclusively in striatum. Finally, no 24-h modulation was observed for hippocampal cell proliferation, although higher values were present during lights off. These results demonstrated a clear daily modulation of FADD in several key brain regions, with a more prominent regulation during the active time of rats, and suggested a key role for FADD, and molecular partners, in the normal physiological functioning of the brain's daily rhythmicity, which if disrupted might participate in the development of certain pathologies.

Regulation of Cortico-Thalamic JNK1/2 and ERK1/2 MAPKs and Apoptosis-Related Signaling Pathways in PDYN Gene-Deficient Mice Following Acute and Chronic Mild Stress

The crosstalk between the opioidergic system and mitogen-activated protein kinases (MAPKs) has a critical role in mediating stress-induced behaviors related to the pathophysiology of anxiety. The present study evaluated the basal status and stress-induced alterations of cortico-thalamic MAPKs and other cell fate-related signaling pathways potentially underlying the anxiogenic endophenotype of PDYN gene-deficient mice. Compared to littermates, PDYN knockout (KO) mice had lower cortical and or thalamic amounts of the phospho-activated MAPKs c-Jun N-terminal kinase (JNK1/2) and extracellular signal-regulated kinase (ERK1/2). Similarly, PDYN-KO animals displayed reduced cortico-thalamic densities of total and phosphorylated (at Ser191) species of the cell fate regulator Fas-associated protein with death domain (FADD) without alterations in the Fas receptor. Exposure to acute restraint and chronic mild stress stimuli induced the robust stimulation of JNK1/2 and ERK1/2 MAPKs, FADD, and Akt-mTOR pathways, without apparent increases in apoptotic rates. Interestingly, PDYN deficiency prevented stress-induced JNK1/2 and FADD but not ERK1/2 or Akt-mTOR hyperactivations. These findings suggest that cortico-thalamic MAPK- and FADD-dependent neuroplasticity might be altered in PDYN-KO mice. In addition, the results also indicate that the PDYN gene (and hence dynorphin release) may be required to stimulate JNK1/2 and FADD (but not ERK1/2 or Akt/mTOR) pathways under environmental stress conditions.

Chronic exposure to methadone impairs memory, induces microgliosis, astrogliosis and neuroinflammation in the hippocampus of adult male rats

Methadone is a centrally-acting synthetic opioid analgesic widely used in methadone maintenance therapy (MMT) programs throughout the world. Given its neurotoxic effects, particularly on the hippocampus, this study aims to address the behavioral and histological alterations in the hippocampus associated with methadone administration. To do so, twenty-four adult male albino rats were randomized into two groups, methadone treatment and control. Methadone was administered subcutaneously (2.5-10 mg/kg) once a day for two consecutive weeks. A comparison was drawn with behavioral and structural changes recorded in the control group. The results showed that methadone administration interrupted spatial learning and memory function. Accordingly, treating rats with methadone not only induced cell death but also prompted the actuation of microgliosis, astrogliosis, and apoptotic biomarkers. Furthermore, the results demonstrated that treating rats with methadone decreased the complexity of astrocyte processes and the complexity of microglia processes. These findings suggest that methadone altered the special distribution of neurons. Also, a substantial increase was observed in the expression of TNF-α due to methadone. According to the findings, methadone administration exerts a neurodegenerative effect on the hippocampus via dysregulation of microgliosis, astrogliosis, apoptosis, and neuro-inflammation.

Metformin prevents morphine-induced apoptosis in rats with diabetic neuropathy: a possible mechanism for attenuating morphine tolerance

Morphine is a drug of choice for the treatment of severe and chronic pain, but tolerance to the antinociceptive effect limits its use. The development of tolerance to morphine has recently been associated with neuronal apoptosis. In this study, our aim was to investigate the effects of metformin on morphine-induced neuronal apoptosis and antinociceptive tolerance in diabetic rats. Three days of cumulative dosing were administered to establish morphine tolerance in rats. The antinociceptive effects of metformin (50 mg/kg) and test dose of morphine (5 mg/kg) were considered at 30-min intervals by thermal antinociceptive tests. To induce diabetic neuropathy, streptozotocin (STZ, 65 mg/kg) was injected intraperitoneally. ELISA kits were used to measure caspase-3, bax, and bcl-2 levels from dorsal root ganglion (DRG) tissue. Semi-quantitative scoring system was used to evaluate apoptotic cells with the the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) method. The findings suggest that co-administration of metformin with morphine to diabetic rats showed a significant increase in antinociceptive effect compared to morphine alone. The antinociceptive tests indicated that metformin significantly attenuated morphine antinociceptive tolerance in diabetic rats. In addition, metformin decreased the levels of apoptotic proteins caspase 3 and Bax in DRG neurons, while significantly increased the levels of antiapoptotic Bcl-2. Semi-quantitative scoring showed that metformin provided a significant reduction in apoptotic cell counts in diabetic rats. These data revealed that metformin demonstrated antiapoptotic activity in diabetic rat DRG neurons and attenuated morphine tolerance. The antiapoptotic activity of metformin probably plays a significant role in reducing morphine tolerance.

The Dose-Dependent Effects of Multifunctional Enkephalin Analogs on the Protein Composition of Rat Spleen Lymphocytes, Cortex, and Hippocampus; Comparison with Changes Induced by Morphine

This work aimed to test the effect of 7-day exposure of rats to multifunctional enkephalin analogs LYS739 and LYS744 at doses of 3 mg/kg and 10 mg/kg on the protein composition of rat spleen lymphocytes, brain cortex, and hippocampus. Alterations of proteome induced by LYS739 and LYS744 were compared with those elicited by morphine. The changes in rat proteome profiles were analyzed by label-free quantification (MaxLFQ). Proteomic analysis indicated that the treatment with 3 mg/kg of LYS744 caused significant alterations in protein expression levels in spleen lymphocytes (45), rat brain cortex (31), and hippocampus (42). The identified proteins were primarily involved in RNA processing and the regulation of cytoskeletal dynamics. In spleen lymphocytes, the administration of the higher 10 mg/kg dose of both enkephalin analogs caused major, extensive modifications in protein expression levels: LYS739 (119) and LYS744 (182). Among these changes, the number of proteins associated with immune responses and apoptotic processes was increased. LYS739 treatment resulted in the highest number of alterations in the rat brain cortex (152) and hippocampus (45). The altered proteins were functionally related to the regulation of transcription and cytoskeletal reorganization, which plays an essential role in neuronal plasticity. Administration with LYS744 did not increase the number of altered proteins in the brain cortex (26) and hippocampus (26). Our findings demonstrate that the effect of κ-OR full antagonism of LYS744 is opposite in the central nervous system and the peripheral region (spleen lymphocytes).

The other side of the coin: Positive view on the role of opioids in cancer

Opioids have been used for medicinal purposes as an analgesic and recreational purposes as a euphorigenic throughout human history. Cancer patients are often treated with different doses of opioids concurrently with anti-cancer drugs for pain relief without exhibiting excessive adverse effects. The intersection of the biology of pain, opioid therapy, and disease progression represents the crux of the matters and is of potentially great importance in cancer care. For more than 20 years, multiple investigations have focused on the stimulatory effects of opioids on cancer cell growth, while in-depth studies on the inhibitory effects on cancer cell growth development have usually been neglected. This paper reviews the evidence regarding opioid therapies and their anti-cancer effects on various malignancies. Likewise, we have a glimpse into the molecular mechanisms necessary for pinpointing their positive or negative impacts on malignancies to raise awareness and stimulate more excellent dialogue regarding their carcinogenic/anticarcinogenic roles.

Effects of different intensities of treadmill exercise on cued fear extinction failure, hippocampal BDNF decline, and Bax/Bcl-2 ratio alteration in chronic-morphine treated male rats

Chronic morphine impairs cued fear extinction, which may contribute to the high prevalence of anxiety disorders and the replase of opiate addiction. This work investigated the effects of forced exercise with different intensities on cued fear extinction impairment and alternations of hippocampal BDNF and apoptotic proteins induced by chronic morphine. Rats were injected with bi-daily doses of morphine or saline for ten days and then received a cued or contextual fear conditioning training, which was followed by fear extinction training for four consecutive days. Cued, but the not contextual fear response was impaired in morphine-treated rats. Then, different saline or morphine-treated rats underwent forced exercise for 4-weeks with light, moderate or high intensities. Subsequently, rats received a cued fear conditioning followed by four days of extinction training, and the expression of hippocampal BDNF and apoptotic proteins was determined. A relatively long time after the last injection of morphine (35 days), rats again showed cued fear extinction failure and reduced hippocampal BDNF, which recovered by light and moderate, but not high exercise. Light and moderate, but not high-intensity treadmill exercise enhanced the up-regulation of Bcl-2 and down-regulation of the Bax proteins in both saline- and morphine-treated rats, which shifted the balance between pro-apoptotic and anti-apoptotic factors in favor of cell survival. These findings highlight the impact of exercise up to moderate intensity in the recovery of cued extinction failure, more likely via BDNF in addicted individuals.

Morphine dependence and withdrawal-induced changes in mouse Sertoli cell (TM4) line: Evaluation of apoptotic, inflammatory and oxidative stress biomarkers

Chronic morphine exerts deleterious effects on testicular function through either suppression of germ cells or somatic including Sertoli cells, probably through the activation of inflammatory, oxidative, and apoptosis biomarkers. Thus, the present study aimed to investigate whether the damaging effects of morphine dependence were reversed by the spontaneous morphine withdrawal or incubation with methadone and/or naloxone in Sertoli (TM4) cells using an in- vitro cell model of morphine dependence. Morphine dependence in TM4 cells was induced by increasing daily doses of morphine for 10 days and then maintained for two weeks in 5 μM. The cAMP levels were measured for an evaluation of morphine dependence. The cell viability and inflammatory, oxidative, apoptosis biomarkers, and glial cell-derived neurotrophic factor (GDNF) were measured after the end of treatment following the incubation of cells with methadone and naloxone and spontaneous withdrawal from morphine. We found that morphine dependence decreased cell viability, GDNF level and increased the levels of pro-oxidant, pro-inflammatory, and apoptotic biomarkers in TM4 cells, while spontaneous withdrawal from morphine and by naloxone decreased the levels of the biomarkers of pro-inflammatory and apoptotic in TM4 cells. Also, despite the low levels of pro-inflammatory factors following morphine withdrawal by methadone, it increased the cleaved/pro-caspase3 ratio in TM4 cells. This study showed that morphine dependence increased apoptosis probably via oxidative stress and inflammation pathways in TM4 cells. Also, it seems likely that spontaneous and naloxone withdrawal have beneficial consequences in the treatment of morphine dependence than methadone therapy, although they may require longer incubation periods.

The protective effect of zinc on morphine-induced testicular toxicity via p53 and Akt pathways: An in vitro and in vivo approach

BACKGROUND

Chronic use of morphine is associated with reproductive complications, such as hypogonadism and infertility. While the side effects of morphine have been extensively studied in the testis, much less is known regarding the effects of morphine on Sertoli cells and the effects of zinc on morphine-induced testicular injury as well as their underlying mechanisms. Therefore, the purpose of this study was to investigate the effect of morphine (alone and co-administered with zinc) on cell viability and apoptosis of the testicular (Sertoli) cells as well as the tumor suppressor p53 and phosphorylated-protein kinase B (p-Akt) protein levels in both in vitro and in vivo models.

METHODS

Cultured Sertoli cells were exposed to morphine (23 μM), zinc (8 μM), and zinc prior to morphine and their effects on Sertoli cell viability and apoptosis were investigated. Morphine (3 mg/kg) and zinc (5 mg/kg, 1 h before morphine) were also injected intraperitoneally to rats and then the apoptotic changes in the testis were evaluated.

RESULTS

Cell viability and p-Akt protein levels decreased in morphine-treated cells, while apoptosis and p53 protein expression increased in these cells. Pretreatment with zinc recovered morphine-induced apoptotic effects, as well as over-expression of p53 and down-regulation of p-Akt. These findings were supported by a subsequent animal study.

CONCLUSION

The present data indicated the protective effect of zinc against morphine-induced testicular (Sertoli) cell toxicity via p53/Akt pathways in both in vivo and in vitro models and suggested the clinical importance of zinc on infertility among chronic opioid users and addicted men.

Prenatal Opioid Exposure Enhances Responsiveness to Future Drug Reward and Alters Sensitivity to Pain: A Review of Preclinical Models and Contributing Mechanisms

The opioid crisis has resulted in an unprecedented number of neonates born with prenatal opioid exposure (POE); however, the long-term effects of POE on offspring behavior and neurodevelopment remain relatively unknown. The advantages and disadvantages of the various preclinical POE models developed over the last several decades are discussed in the context of clinical and translational relevance. Although considerable and important variability exists among preclinical models of POE, the examination of these preclinical models has revealed that opioid exposure during the prenatal period contributes to maladaptive behavioral development as offspring mature including an altered responsiveness to rewarding drugs and increased pain response. The present review summarizes key findings demonstrating the impact of POE on offspring drug self-administration (SA), drug consumption, the reinforcing properties of drugs, drug tolerance, and other reward-related behaviors such as hypersensitivity to pain. Potential underlying molecular mechanisms which may contribute to this enhanced addictive phenotype in POE offspring are further discussed with special attention given to key brain regions associated with reward including the striatum, prefrontal cortex (PFC), ventral tegmental area (VTA), hippocampus, and amygdala. Improvements in preclinical models and further areas of study are also identified which may advance the translational value of findings and help address the growing problem of POE in clinical populations.

The neuroprotective effect of NeuroAid on morphine-induced amnesia with respect to the expression of TFAM, PGC-1α, ΔfosB and CART genes in the hippocampus of male Wistar rats

Morphine is a natural alkaloid which derived from the opium poppy Papaver somniferum. Many studies have reported the effect of morphine on learning, memory and gene expression. CART (cocaine-amphetamine regulated transcript)is an important neuropeptide which has a critical role in physiological processes including drug dependence and antioxidant activity. ΔfosB is a transcription factor which modulates synaptic plasticity and affects learning and memory. TFAM (the mitochondrial transcription factor A) and PGC-1α (Peroxisome proliferator-activated receptor γ coactivator-1α) are critically involved in mitochondrial biogenesis and antioxidant pathways. NeuroAid is a Chinese medicine that induces neuroprotective and anti-apoptotic effects. In this research, we aimed to investigate the effect of NeuroAid on morphine-induced amnesia with respect to the expression of TFAM, PGC-1α, ΔfosB and CART in the rat's hippocampus. In this study, Morphine sulfate (at increasing doses), Naloxone hydrochloride (2.5 mg/kg) and NeuroAid (2.5 mg/kg) were administered intraperitoneal and real-time PCR reactions were done to assess gene expression. The results showed, morphine impaired memory of step-through passive avoidance, while NeuroAid had no effect. NeuroAid attenuated (but not reversed) morphine-induced memory impairment in morphine-addicted rats. Morphine increased the expression of PGC-1α and decreased the expression of CART. However, NeuroAid increased the expression of TFAM, PGC-1α, ΔfosB and CART. NeuroAid restored the effect of morphine on the expression of CART and PGC-1α. In conclusion, morphine impaired memory of step-through passive avoidance and NeuroAid attenuated this effect. The effect of NeuroAid on morphine-induced memory impairment/gene expression may be related to its anti-apoptotic and neuroprotective effects.

The effect of epigallocatechin-3-gallate on morphine-induced memory impairments in rat: EGCG effects on morphine neurotoxicity

AIM OF STUDY

This investigation evaluated the capacity of epigallocatechin-3-gallate (EGCG) as the main polyphenolic compound in the green tea extract against memory impairment and neurotoxicity in morphine-treated rats.

METHODS

To measure the EGCG effect (5 and 50 mg/kg, i.p., co-treated with morphine) on spatial learning and memory of morphine-administrated male Wistar rats (45 mg/kg, s.c., 4 weeks), the Morris water maze test was used. Some apoptotic protein levels (Bax, Bcl-2, and cleaved caspase 3) were evaluated in the hippocampus tissue by the Western blot test. Also, oxidative stress status (malondialdehyde level, glutathione peroxidase, and superoxide dismutase activity) was measured in hippocampus tissue.

RESULTS

The data presented that EGCG treatment (50 mg/kg) inhibited the morphine-induced memory deficits in rats. Also, EGCG administration reduced the apoptosis and oxidative stress in the hippocampus of morphine-treated rats.

CONCLUSIONS

Our data indicate that EGCG can improve memory in morphine-treated rats. Molecular mechanisms underlying the detected effects could be related to the prevention of apoptosis and oxidative stress in the hippocampus of morphine-treated rats.

Exposure to Morphine and Caffeine Induces Apoptosis and Mitochondrial Dysfunction in a Neonatal Rat Brain

Background: Preterm infants experience rapid brain growth during early post-natal life making them vulnerable to drugs acting on central nervous system. Morphine is administered to premature neonates for pain control and caffeine for apnea of prematurity. Simultaneous use of morphine and caffeine is common in the neonatal intensive care unit. Prior studies have shown acute neurotoxicity with this combination, however, little information is available on the mechanisms mediating the neurotoxic effects. The objective of this study was to determine the effects of morphine and caffeine, independently and in combination on mitochondrial dysfunction (Drp1 and Mfn2), neural apoptosis (Bcl-2, Bax, and cell damage) and endothelin (ET) receptors (ET_A and ET_B) in neonatal rat brain. Methods: Male and female rat pups were grouped separately and were divided into four different subgroups on the basis of treatments-saline (Control), morphine (MOR), caffeine (CAFF), and morphine + caffeine (M+C) treatment. Pups in MOR group were injected with 2 mg/kg morphine, CAFF group received 100 mg/kg caffeine, and M+C group received both morphine (2 mg/kg) and caffeine (100 mg/kg), subcutaneously on postnatal days (PND) 3-6. Pups were euthanized at PND 7, 14, or 28. Brains were isolated and analyzed for mitochondrial dysfunction, apoptosis markers, cell damage, and ET receptor expression via immunofluorescence and western blot analyses. Results: M+C showed a significantly higher expression of Bax compared to CAFF or MOR alone at PND 7, 14, 28 in female pups (p < 0.05) and at PND 7, 14 in male pups (p < 0.05). Significantly (p < 0.05) increased expression of Drp1, Bax, and suppressed expression of Mfn2, Bcl-2 at PND 7, 14, 28 in all the treatment groups compared to the control was observed in both genders. No significant difference in the expression of ET_A and ET_B receptors in male or female pups was seen at PND 7, 14, and 28. Conclusion: Concurrent use of morphine and caffeine during the first week of life increases apoptosis and cell damage in the developing brain compared to individual use of caffeine and morphine.

Effect of oleuropein on morphine-induced hippocampus neurotoxicity and memory impairments in rats

Oleuropein, as an olive leaf extract antioxidant polyphenol, has been reported to be a free radical scavenger. This study was done to investigate the effects of oleuropein, against morphine-induced hippocampus neurotoxicity and memory impairment in rats. The Morris water maze (MWM) test was used to assess the effect of oleuropein (5, 15, and 30 mg/kg, i.p., co-administrated with morphine) on spatial learning and memory of male Wistar rats which were treated with morphine sulfate (45 mg/kg, s.c., 4 weeks). In order to evaluate the cleaved caspase-3, Bax, and Bcl2 protein expression (as biochemical markers of apoptosis) in CA1 area of hippocampus tissue, the western blot test was used. Also, to evaluate the oxidative stress status of hippocampus CA1 area tissue, the malondialdehyde (MDA) level, superoxide dismutase (SOD) activity, and glutathione peroxidase (GPx) activity were assessed. The data showed that oleuropein treatment (15 and 30 mg/kg) improves the spatial learning and memory impairments in morphine-treated animals. Also, oleuropein treatment decreased the apoptosis and oxidative stress levels in the hippocampus CA1 area of morphine-treated rats. Oleuropein can prevent the spatial learning and memory impairments in morphine-treated rats. Molecular mechanisms underlying the observed effects could be at least partially related to the inhibition of neuronal apoptosis and oxidative stress in the hippocampus CA1 area of morphine-treated rats.

Immunohistochemical Assessment of Inflammation and Regeneration in Morphine-Dependent Rat Brain

Background

Opioids are amongst the most common abused drugs. Pathologic studies on opioid abuse are limited since the evaluation of inflammation and regeneration in brain tissue is not as simple as other tissues of the body. Thus, the present study aimed to determine the relationship between the dependence on morphine and inflammatory and regenerative processes.

Methods

In this experimental study, 48 male wistar rats were divided into 6 groups. The dependent groups (3 groups) received 0.4 mg/ml morphine in drinking water for 7, 28, and 56 days. The control groups (3 groups) received sucrose solution in drinking water for the same period. The histopathological studies of the brain sample were done. The slides were stained by hematoxylin and eosin (H&E) and immunohistochemistry (IHC) staining method. The areas of brain were evaluated in terms of lymphocytic infiltration and glial scar.

Findings

A significant difference was observed in the mean number of cells in the glial scar of the dependent group 3 (dependent for 56 days) among the control group (P = 0.040). Further, a significant relationship was reported between the increased duration of morphine use and the number of created scar glial cells. Furthermore, a significant increase in the number of astrocytes was observed in the affected areas.

Conclusion

After long-term use, opioids can result in increased number of astrocytes and creating glial scar centers in the affected areas in response to the inflammation.

Fragile X-Associated Neuropsychiatric Disorders (FXAND)

Fragile X syndrome (FXS) is caused by the full mutation (>200 CGG repeats) in the Fragile X Mental Retardation 1 (FMR1) gene. It is the most common inherited cause of intellectual disability (ID) and autism. This review focuses on neuropsychiatric disorders frequently experienced by premutation carriers with 55 to 200 CGG repeats and the pathophysiology involves elevated FMR1 mRNA levels, which is different from the absence or deficiency of fragile X mental retardation protein (FMRP) seen in FXS. Neuropsychiatric disorders are the most common problems associated with the premutation, and they affect approximately 50% of individuals with 55 to 200 CGG repeats in the FMR1 gene. Neuropsychiatric disorders in children with the premutation include anxiety, ADHD, social deficits, or autism spectrum disorders (ASD). In adults with the premutation, anxiety and depression are the most common problems, although obsessive compulsive disorder, ADHD, and substance abuse are also common. These problems are often exacerbated by chronic fatigue, chronic pain, fibromyalgia, autoimmune disorders and sleep problems, which are also associated with the premutation. Here we review the clinical studies, neuropathology and molecular underpinnings of RNA toxicity associated with the premutation. We also propose the name Fragile X-associated Neuropsychiatric Disorders (FXAND) in an effort to promote research and the use of fragile X DNA testing to enhance recognition and treatment for these disorders.

Morphine-alcohol treatment impairs cognitive functions and increases neuro-inflammatory responses in the medial prefrontal cortex of juvenile male rats

In the developed and developing world, opioid consumption in combination with alcohol has become one of the substances abused. In this experiment, we examined the effects of alcohol, morphine, and morphine+alcohol combination on cognitive functions and neuroinflammatory responses in the medial prefrontal cortex (mPFC) of juvenile male rats. Alcohol (1.0 ml of 15% v/v ethanol twice daily, subcutaneously, 7 hours apart), morphine (0.5 ml/kg of 0.4 mg/kg morphine chlorate twice daily, subcutaneously, 7 hours apart), morphine+alcohol co-treatment (0.5 ml/kg of 0.4 mg/kg morphine chlorate+1.0 ml of 15% v/v ethanol twice daily, subcutaneously, 7 hours apart) were administered for 21 days. Treatment with morphine+alcohol significantly impairs cognition functions in the Morris water maze, passive avoidance, and novel object recognition tests, furthermore, the treatment significantly increased the quantitative count of astrocytic cells and also conferred marked neuronal cell death in the mPFC, which were studied by glial fibrillary acidic protein immunochemistry for astrocytes and Cresyl violet for Nissl's substance distribution in neurons respectively. These results suggest that alcohol, morphine, and morphine+alcohol co-treatment may trigger cognitive deficits and neuroinflammatory responses in the brain.

A possible biomarker for methadone related deaths

Methadone (MTH) concentrations in those dying of MTH toxicity totally overlap concentrations where the presence of MTH is only an incidental finding, making it very difficult to make distinctions in actual cases. A biomarker, be it anatomical or biochemical for MTH toxicity is badly needed, particularly if that markers were known to disrupt effective ventilation. Because the brainstem houses the regulatory centers for cardiorespiratory-control enters, it would seem to be the most likely anatomical site to seek abnormalities in cardiorespiratory control.

OBJECTIVE

To locate and describe the cells of nucleus of the solitary tract (TS)(NTS) in human brainstem and determine if neuronal cell death, either necrotic or apoptotic, within the TS of humans is more common in deaths due directly to MTH toxicity than with in the solitary tract itself.

DESIGN, SETTING, PARTICIPANTS

This was a single cohort study of MTH related decedents autopsied at a large university hospital. Each decedent had a recent history of non medical/illicit MTH use and had been pronounced dead in the field, prior to ever reaching the hospital. Complete autopsy and complete toxicology testing were performed on the formalin fixed brains of each individual. Multiple blocks were prepared of the area of interest, namely the tissue lying immediately between the inferior and the super colliculi. This volume, by definition, would have included the area of the Rostral Ventrolateral Medulla (RVLM), the location of the TS. Immunohistochemistry studies utilizing caspase-9 reaction (a protease enzyme involved in the process of preprogrammed death) were performed in order to estimate the degree and proportion of neuronal apoptosis, and also access the degree of classical necrosis within the NTS.

MAIN OUTCOMES AND MEASURES

The primary outcome measure was the presence or absence of neuronal apoptosis and/or necrosis within the NTS.

RESULTS

Cells displaying evidence of early apoptosis and advanced apoptosis, consisting primarily of nuclear fragmentation, admixed with other neurons displaying the features of classic necrosis were found. Evidence of classic necrosis was identifiable in most of the controls, though minor degrees of apoptosis were identifiable with Caspase staining and quantitative image analysis of immunohistochemical stains.

CONCLUSIONS

and Relevance: Our study shows that neurons, primarily along the TS, but occasionally in other cell nuclei (even controls) are vulnerable, both to direct MTH toxicity (via apoptosis) and indirectly (via hypoxia leading to classical cell necrosis). When MTH is found to be present in significant concentrations, but apoptotic lesions are absent, it would be reasonable to assume that MTH was not primarily the cause of cardiorespiratory arrest.

Specialized roles of neurofilament proteins in synapses: Relevance to neuropsychiatric disorders

Neurofilaments are uniquely complex among classes of intermediate filaments in being composed of four subunits (NFL, NFM, NFH and alpha-internexin in the CNS) that differ in structure, regulation, and function. Although neurofilaments have been traditionally viewed as axonal structural components, recent evidence has revealed that distinctive assemblies of neurofilament subunits are integral components of synapses, especially at postsynaptic sites. Within the synaptic compartment, the individual subunits differentially modulate neurotransmission and behavior through interactions with specific neurotransmitter receptors. These newly uncovered functions suggest that alterations of neurofilament proteins not only underlie axonopathy in various neurological disorders but also may play vital roles in cognition and neuropsychiatric diseases. Here, we review evidence that synaptic neurofilament proteins are a sizable population in the CNS and we advance the concept that changes in the levels or post-translational modification of individual NF subunits contribute to synaptic and behavioral dysfunction in certain neuropsychiatric conditions.

Methadone-induced Damage to White Matter Integrity in Methadone Maintenance Patients: A Longitudinal Self-control DTI Study

Methadone maintenance treatment (MMT) can induce impairments in brain function and structure, despite its clinical effectiveness. However, the effect of chronic MMT on brain white matter (WM) is not fully known. Thirty-three MMT patients underwent diffusion tensor imaging (DTI) twice – at the start of the study (Scan₁) and one year later (Scan₂). Tract-based spatial statistics were used to investigate changes in fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD) between the two scans. The correlations between DTI indices and methadone consumption and neuropsychological status were analysed. We found significantly decreased FA, decreased AD and increased RD in Scan₂ in extensive WM regions; overlapping regions were found in the left posterior limb and the retrolenticular part of internal capsule, superior and posterior corona radiata, bilateral external capsule and the right superior longitudinal fasciculus. In addition, the change of FA in the overlapping regions was positively correlated with the accumulated dosage of methadone use, the RD value in Scan₂ and non-planning impulsiveness (NPI) measured at follow-up. The results suggest that methadone has damaging effects on WM integrity. The dose-dependent pattern and characteristics of the impairment may suggest new strategies for MMT.

Methadone use in a male with the FMRI premutation and FXTAS

The fragile X-associated tremor ataxia syndrome (FXTAS) is caused by the premutation in FMR1 gene. Recent reports of environmental toxins appear to worsen the progression of FXTAS. Here we present a case of male adult with FXTAS and a long history of methadone use. The patient shows a faster progression in both symptoms of disease and MRI changes compared to what is typically seen in FXTAS. There has been no research regarding the role of narcotics in onset, progression, and severity of FXTAS symptoms. However, research has shown that narcotics can have a negative impact on several neurodegenerative diseases, and we hypothesize that in this particular case, methadone may have contributed to a faster progression of FXTAS as well as exacerbating white matter disease through RNA toxicity seen in premutation carriers.

Neuropathological alterations in drug abusers : The involvement of neurons, glial, and vascular systems

Because the effects of drug abuse on the cellular elements of the human brain have not been studied systematically, an investigation was performed using histology, immunohistochemistry, and morphometry. The main cortical and subcortical brain areas of 50 polydrug deaths were analyzed as compared with controls.In the brains of drug abusers, a significant neuronal loss was present. Interestingly, the number of glial fibrillary acidic protein (GFAP)-positive astrocytes was reduced. the numerical density of perivascular and parenchymal microglia was increased in the white matter and in most subcortical regions. In the white matter there were widespread β-amyloid precursor protein deposits. Furthermore, there was a prominent vascular hyalinosis, endothelial cell proliferation, and a loss of immunoreactivity for collagen type IV within the vascular basal lamina.The neuronal loss seems to be the result of a direct impairment of nerve cells and, indirectly, to a damage of astrocytes, axons, and the microvasculature. The reduction of GFAP-positive astrocytes is also indicative of a drug-induced damage. The axonal injury suggests a toxic-metabolic drug effect, whereas the concomitant activation of microglia is indicative of a long-standing progressive process. The noninflammatory vasculopathy can be considered as the morphological substrate of a disturbed blood-brain barrier. Our findings demonstrate that drugs of abuse initiate a cascade of interacting toxic, vascular, and hypoxic factors that finally result in widespread disturbances within the complex network of central nervous system cell-cell interactions.

Pioglitazone prevents morphine antinociceptive tolerance via ameliorating neuroinflammation in rat cerebral cortex

BACKGROUND

Opioid induced neuroinflammation is shown to be implicated in opioid analgesic tolerance development. In the present study the effect of pioglitazone on morphine-induced tolerance and neuroinflammation in the cerebral cortex of the rat was investigated.

MATERIALS AND METHODS

Various groups of rats received morphine (10mg/kg; ip) and vehicle (po), or morphine (10mg/kg) and pioglitazone (20 or 40 mg/kg; po) once a day for 17 days. In order to determine the possible involvement of PPAR-γ in the pioglitazone effect, one group of rats received PPAR-γ antagonist, GW-9662 (2mg/kg; sc), and pioglitazone (40 mg/kg) and morphine once daily for 17 days. Nociception was assessed using a tail flick apparatus and the percentage of the maximal possible effect was calculated as well. On 18th day, 2h after the last morphine injection, the cerebral cortex of the animals were harvested and the tissue levels of tumour necrosis factor alpha, interleukin-1beta, interleukin-6, interleukin-10 and nuclear factor-kappa B activity were determined.

RESULTS

Co-administration of pioglitazone (40 mg/kg) with morphine not only attenuated morphine-induced tolerance, but also prevented the up-regulation of pro-inflammatory cytokines (tumour necrosis factor alpha, interleukin-1beta, interleukin-6) and nuclear factor-kappa B activity in the rat cerebral cortex. Moreover, GW-9662 (2mg/kg) administration 30 min before pioglitazone, antagonized the above mentioned pioglitazone-induced effects.

CONCLUSION

It is concluded that oral administration of pioglitazone attenuates morphine-induced tolerance. This effect of pioglitazone may be, at least in part, due to its anti-inflammatory property which suppressed the cortical pro-inflammatory cytokine and inhibited of nuclear factor-kappa B activity.

Effects of voluntary and treadmill exercise on spontaneous withdrawal signs, cognitive deficits and alterations in apoptosis-associated proteins in morphine-dependent rats

Chronic exposure to morphine results in cognitive deficits and alterations of apoptotic proteins in favor of cell death in the hippocampus, a brain region critically involved in learning and memory. Physical activity has been shown to have beneficial effects on brain health. In the current work, we examined the effects of voluntary and treadmill exercise on spontaneous withdrawal signs, the associated cognitive defects, and changes of apoptotic proteins in morphine-dependent rats. Morphine dependence was induced through bi-daily administrations of morphine (10mg/kg) for 10 days. Then, the rats were trained under two different exercise protocols: mild treadmill exercise or voluntary wheel exercise for 10 days. After exercise training, their spatial learning and memory and aversive memory were examined by a water maze and by an inhibitory avoidance task, respectively. The expression of the pro-apoptotic protein Bax and the anti-apoptotic protein Bcl-2 in the hippocampus were determined by immunoblotting. We found that chronic exposure to morphine impaired spatial and aversive memory and remarkably suppressed the expression of Bcl-2, but Bax expression remained constant. Both voluntary and treadmill exercise alleviated memory impairment, increased the expression of Bcl-2 protein, and only the later suppressed the expression of Bax protein in morphine-dependent animals. Moreover, both exercise protocols diminished the occurrence of spontaneous morphine withdrawal signs. Our findings showed that exercise reduces the spontaneous morphine-withdrawal signs, blocks the associated impairment of cognitive performance, and overcomes morphine-induced alterations in apoptotic proteins in favor of cell death. Thus, exercise may be a useful therapeutic strategy for cognitive and behavioral deficits in addict individuals.

The neurodevelopmental impact of neonatal morphine administration

Medical management of newborn infants often necessitates recurrent painful procedures, which may alter nociceptive pathways during a critical developmental period and adversely effect neuropsychological outcomes. To mitigate the effects of repeated painful stimuli, opioid administration for peri-procedural analgesia and ICU (intensive care unit) sedation is common in the NICU (neonatal intensive care unit). A growing body of basic and animal evidence suggests potential long-term harm associated with neonatal opioid therapy. Morphine increases apoptosis in human microglial cells, and animal studies demonstrate long-term changes in behavior, brain function, and spatial recognition memory following morphine exposure. This comprehensive review examines existing preclinical and clinical evidence on the long-term impacts of neonatal pain and opioid therapy.

A new pharmacological role for donepezil: attenuation of morphine-induced tolerance and apoptosis in rat central nervous system

BACKGROUND

Tolerance to the analgesic effect of opioids is a pharmacological phenomenon that occurs after their prolonged administration. It has been shown that morphine-induced tolerance is associated with apoptosis in the central nervous system and neuroprotective agents which prevented apoptosis signaling could attenuate tolerance to the analgesic effects. On the other hand donepezil, an acetylcholinesterase inhibitor, has been reported to have neuroprotective effects. Therefore in this study, the effect of systemic administration of donepezil on morphine-induced tolerance and apoptosis in the rat cerebral cortex and lumbar spinal cord was evaluated. Various groups of rats received morphine (ip) and different doses of donepezil (0, 0.5, 1, 1.5 mg/kg/day). Nociception was assessed using tail flick apparatus. Tail flick latency was recorded when the rat shook its tail. For apoptosis assay other groups of rats received the above treatment and apoptosis was evaluated by in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method.

RESULTS

The results showed that administration of donepezil (0.5, 1, 1.5 mg/kg, ip) delayed the morphine tolerance for 9, 12 and 17 days, respectively. Furthermore pretreatment injection of donepezil attenuated the number of apoptotic cells in the cerebral cortex and lumbar spinal cord compared to the control group.

CONCLUSION

In conclusion, we found that systemic administration of donepezil attenuated morphine-induced tolerance and apoptosis in the rat cerebral cortex and lumbar spinal cord.

Role of phosphodiesterase inhibitor Ibudilast in morphine-induced hippocampal injury

BACKGROUND

Opioid drugs are used in the treatment of acute post-surgical pain and chronic pain, such as those associated with cancer. Opioid used is associated with complications such as analgesic tolerance, dependence and opioid abuse. The molecular mechanisms of unwanted opioid responses are varied but recent advances have highlighted elevations in pro-inflammatory cytokines and pro-inflammatory glial following chronic administration of morphine. In this study we investigated the neurodegenerative effects of morphine through its effects on Toll-Like Receptor 4 (TLR4) in the male rat hippocampus and evaluated the level of Interleukin-1 beta (IL-1β). Then we compared the difference between inhibitory effects on mu opioid receptors (by β-Funaltrexamine, β-FNA) and TLR4 (by Ibudilast). Subsequently, we assessed the amount of IL-1β and the number of granular cells in male rat hippocampus.

METHODS

Adult male rats (n=24) were treated with sucrose, morphine, Ibudilast (7.5 mg/kg) and β-FNA (20 mg/kg) for 30 days. Their brains were isolated and hemisected with one hippocampus for granular cell and the other used for IL-1 β immunoblotting.

RESULTS

Data showed that Ibudilast suppresses IL-1 β expression significantly more than β-FNA. The granular cell count displayed significant differences.

CONCLUSIONS

Our results suggested that Ibudilast can be used for controlling and treatment of morphine-induced CNS inflammations or traumatic conditions.

Stereological study of the effects of morphine consumption and abstinence on the number of the neurons and oligodendrocytes in medial prefrontal cortex of rats

Quantitative studies to date on the effects of opioid consumption and abstinence on the nervous system using modern stereological methods have not received enough attention. In addition, they have yielded controversial results. The present study was conducted to investigate the effects of morphine, with or without abstinence, on the neurons and oligodendrocytes of the medial prefrontal cortex (MPFC) in rats using quantitative stereological methods. The male rats were divided into four groups: the first (saline [SAL]) and second (morphine [MOR]) groups were treated with saline and an escalating dose of morphine (5-20 mg/kg) for 30 days, respectively; the third (SAL+abstinence [ABS]) and fourth (MOR+ABS) groups were treated in the same manner as the previous groups plus they had a 30-day abstinence period. The results showed that the volume of the MPFC and its subdivisions decreased by approximately 15% in the MOR group compared with that in the SAL group (P<0.05). In addition, the volume decreased by approximately 24% in the MOR+ABS group compared with that in the SAL+ABS group (P<0.05). The number of neurons in the MOR and MOR+ABS groups decreased by approximately 44% and 35%, respectively, compared with that in their corresponding control groups. Moreover, the number of the oligodendrocytes in the MOR and MOR+ABS groups decreased by approximately 41% and 37%, respectively. No significant difference was noted in the number of cells in the MOR and MOR+ABS groups. In conclusion, morphine consumption leads to a permanent reduction in the number of neurons and oligodendrocytes, and no additional neuron and oligodendrocyte loss occurs after abstinence.

The role of anesthetic drugs in liver apoptosis

CONTEXT

The modern practice of anesthesia is highly dependent ona group of anesthetic drugs which many of them are metabolized in the liver.

EVIDENCE ACQUISITION

The liver, of course, usually tolerates this burden. However, this is not always an unbroken rule. Anesthetic induced apoptosis has gained great concern during the last years; especially considering the neurologic system.

RESULTS

However, we have evidence that there is some concern regarding their effects on the liver cells. Fortunately not all the anesthetics are blamed and even some could be used safely, based on the available evidence.

CONCLUSIONS

Besides, there are some novel agents, yet under research, which could affect the future of anesthetic agents' fate regarding their hepatic effects.

Substituting a long-acting dopamine uptake inhibitor for cocaine prevents relapse to cocaine seeking

The treatment of cocaine addiction remains a challenge. The dopamine replacement approach in cocaine addiction involves the use of a competing dopaminergic agonist that might suppress withdrawal and drug craving in abstinent individuals. Although it has long been postulated that such an approach may be therapeutically successful, preclinical or clinical evidence showing its effectiveness to prevent relapse is scant. We used in rats a procedure that involved substitution of the N-substituted benztropine analog 3α-[bis(4'-fluorophenyl)methoxy]-tropane (AHN-1055), a long-acting dopamine uptake inhibitor (DUI), for cocaine. Maintenance treatment was self-administered. After extinction, reinstatement of drug seeking was induced by cocaine priming. We measured the contents of brain-derived neurotrophic factor (BDNF), c-Fos and Fas-associated death domain (FADD) proteins in the medial prefrontal cortex (mPFC) following reinstatement. DUI, but not amphetamine, substitution led to extinction of active lever presses, as did saline substitution. DUI substitution significantly reduced cocaine-induced reinstatement of drug-seeking behavior, which was strongly elicited after saline substitution. Rats passively yoked to DUI also showed reduced cocaine-primed reinstatement. Reductions in drug seeking during reinstatement were matched by downward shifts in the contents of BDNF, c-Fos and FADD proteins in the mPFC, which were elevated in relapsing rats. These data indicate that DUI substitution not only leads to extinction of self-administration behavior but also prevents reinstatement of drug seeking induced by cocaine re-exposure. Thus, DUI substitution therapy using compounds with low abuse potential, even if received passively in the context previously paired with drug taking, may provide an effective treatment for stimulant addiction.

Ovary cells apoptosis in opium-addicted diabetic and non-diabetic rats

Background

Apoptosis is a physiological mechanism of cell death and it can be triggered by a variety of internal and external stimuli. It has been indicated that some opium derivatives develop cell apoptosis.

Objectives

The aim of this investigation was to evaluate the effect of opium addiction on ovary cell apoptosis in diabetic and non-diabetic Wistar rats.

Materials and Methods

This experimental study was done on control, control-addicted, diabetic and diabetic-addicted rats. DNA fragmentation as a biomarker of apoptosis was determined by the TUNEL assay.

Results

The blood glucose concentration in diabetic-addicted and diabetic rats was increased when compared to control (P < 0.001). There was no significant difference between weights of control, control-addicted (non-diabetic) and diabetic-addicted groups during this study. The results of this study indicated that apoptosis in addicted and diabetic-addicted ovary cells was significantly higher than in diabetic group, and also apoptosis in addicted group was significantly more than the control rats. In addition, we found that ovary cells apoptosis of diabetic rats were significantly less than in control group.

Conclusions

Overall, these findings suggest that opium-addiction could play an important role in ovary cell apoptosis and could be very harmful for the reproductive system. Also, ovary cells of non-diabetic rats are more susceptible to opium-induced apoptosis than those of diabetic.

Chronic treatment with selective I2-imidazoline receptor ligands decreases the content of pro-apoptotic markers in rat brain

Selective I(2)-imidazoline receptor ligands induce neuroprotection through various molecular mechanisms including blockade of N-methyl-D-aspartate (NMDA) receptors. To investigate new neuroprotective mechanisms associated with I(2)-imidazoline receptors, the effects of selective (2-styryl-2-imidazoline (LSL 61122), 2-(2-benzofuranyl)-2-imidazoline (2-BFI), 2-(4,5-dihydroimidazol-2-yl) quinoline hydrochloride (BU-224)) and non-selective (idazoxan) I(2)-drugs on canonical apoptotic pathways were assessed in rat brain cortex. The acute treatment with LSL 61122 (10 mg/kg) reduced the content of mitochondrial (pro-apoptotic) Bax (-33%) and cytochrome c (-31%), which was prevented by idazoxan, an I(2)-receptor antagonist. The sustained stimulation of I(2)-imidazoline receptors with selective drugs (10 mg/kg, every 12 h for seven days) was associated with down-regulation of key components of the extrinsic (Fas receptor: -20%; Fas associated protein with death domain (FADD) adaptor: -47-54%) and/or intrinsic (Bax: -20-23%; cytochrome c: -22-28%) apoptotic signalling and/or up-regulation of survival anti-apoptotic factors (p-Ser194 FADD/FADD ratio: +1.6-2.5-fold; and/or Bcl-2/Bax ratio: +1.5-fold), which in the long-term could dampen cell death in the brain. Similar chronic treatments with LSL 60101 (the imidazole analogue of 2-BFI) and idazoxan (a mixed I(2)/α(2)-ligand) did not induce significant alterations of pro- or anti-apoptotic proteins. The disclosed anti-apoptotic mechanisms of selective I(2)-imidazoline drugs may work in concert with other molecular mechanisms of neuroprotection (e.g. blockade of NMDA receptors) that are engaged by I(2)-ligands.

Global changes in the rat heart proteome induced by prolonged morphine treatment and withdrawal

Morphine belongs among the most commonly used opioids in medical practice due to its strong analgesic effects. However, sustained administration of morphine leads to the development of tolerance and dependence and may cause long-lasting alterations in nervous tissue. Although proteomic approaches enabled to reveal changes in multiple gene expression in the brain as a consequence of morphine treatment, there is lack of information about the effect of this drug on heart tissue. Here we studied the effect of 10-day morphine exposure and subsequent drug withdrawal (3 or 6 days) on the rat heart proteome. Using the iTRAQ technique, we identified 541 proteins in the cytosol, 595 proteins in the plasma membrane-enriched fraction and 538 proteins in the mitochondria-enriched fraction derived from the left ventricles. Altogether, the expression levels of 237 proteins were altered by morphine treatment or withdrawal. The majority of changes (58 proteins) occurred in the cytosol after a 3-day abstinence period. Significant alterations were found in the expression of heat shock proteins (HSP27, α-B crystallin, HSP70, HSP10 and HSP60), whose levels were markedly up-regulated after morphine treatment or withdrawal. Besides that morphine exposure up-regulated MAPK p38 (isoform CRA_b) which is a well-known up-stream mediator of phosphorylation and activation of HSP27 and α-B crystallin. Whereas there were no alterations in the levels of proteins involved in oxidative stress, several changes were determined in the levels of pro- and anti-apoptotic proteins. These data provide a complex view on quantitative changes in the cardiac proteome induced by morphine treatment or withdrawal and demonstrate great sensitivity of this organ to morphine.

Regulation of munc18-1 and syntaxin-1A interactive partners in schizophrenia prefrontal cortex: down-regulation of munc18-1a isoform and 75 kDa SNARE complex after antipsychotic treatment

Munc18-1 and syntaxin-1 are crucial interacting molecules for synaptic membrane fusion and neurotransmitter release. Contrasting abnormalities of several proteins of the exocytotic machinery, including the formation of SNARE (synaptobrevin, SNAP-25 and syntaxin-1) complexes, have been reported in schizophrenia. This study quantified in the dorsolateral prefrontal cortex (PFC, Brodmann area 9) the immunocontent of munc18-1a/b isoforms, syntaxin-1A, other presynaptic proteins (synaptotagmin, synaptophysin), and SNARE complexes, as well as the effects of psychoactive drug exposure, in schizophrenia (SZ, n=24), non-schizophrenia suicide (SD, n=13) and major depression (MD, n=15) subjects compared to matched controls (n=39). SZ was associated with normal expression of munc18-1a/b and increased syntaxin-1A (+44%). The presence of antipsychotic drugs reduced the basal content of munc18-1a isoform (-23%) and synaptobrevin (-32%), and modestly reduced that of up-regulated syntaxin-1A (-16%). Munc18-1a and syntaxin-1A protein expression correlated positively in controls but showed a markedly opposite pattern in SZ, regardless of antipsychotic treatment. Thus, the ratio of syntaxin-1A to munc18-1a showed a net increase in SZ (+53/114%). The SNARE complex (75 kDa) was found unaltered in antipsychotic-free and reduced (-28%) in antipsychotic-treated SZ subjects. None of these abnormalities were observed in SD and MD subjects, unexposed or exposed to psychoactive drugs. The results reveal some exocytotic dysfunctions in SZ that are probably related to an imbalance of the interaction between munc18-1a and SNARE (mainly syntaxin-1A) complex. Moreover, antipsychotic drug treatment is associated with lower content of key proteins of the exocytotic machinery, which could result in a destabilization/impairment of neurosecretion.