Cytotoxic effects of amitriptyline in human fibroblasts

Neuronal life or death linked to depression treatment: the interplay between drugs and their stress-related outcomes relate to single or combined drug therapies

Depression is a serious medical condition, typically treated by antidepressants. Conventional monotherapy can be effective only in 60–80% of patients, thus modern psychiatry deals with the challenge of new methods development. At the same moment, interactions between antidepressants and the occurrence of potential side effects raise serious concerns, which are even more exacerbated by the lack of relevant data on exact molecular mechanisms. Therefore, the aims of the study were to provide up-to-date information on the relative mechanisms of action of single antidepressants and their combinations. In this study, we evaluated the effect of single and combined antidepressants administration on mouse hippocampal neurons after 48 and 96 h in terms of cellular and biochemical features in vitro. We show for the first time that co-treatment with amitriptyline/imipramine + fluoxetine initiates in cells adaptation mechanisms which allow cells to adjust to stress and finally exerts less toxic events than in cells treated with single antidepressants. Antidepressants treatment induces in neuronal cells oxidative and nitrosative stress, which leads to micronuclei and double-strand DNA brakes formation. At this point, two different mechanistic events are initiated in cells treated with single and combined antidepressants. Single antidepressants (amitriptyline, imipramine or fluoxetine) activate cell cycle arrest resulting in proliferation inhibition. On the other hand, treatment with combined antidepressants (amitriptyline/imipramine + fluoxetine) initiates p16-dependent cell cycle arrest, overexpression of telomere maintenance proteins and finally restoration of proliferation. In conclusion, our findings may pave the way to better understanding of the stress-related effects on neurons associated with mono- and combined therapy with antidepressants.

Amitriptyline at an Environmentally Relevant Concentration Alters the Profile of Metabolites Beyond Monoamines in Gilt-Head Bream

The antidepressant amitriptyline is a widely used selective serotonin reuptake inhibitor that is found in the aquatic environment. The present study investigates alterations in the brain and the liver metabolome of gilt-head bream (Sparus aurata) after exposure at an environmentally relevant concentration (0.2 µg/L) of amitriptyline for 7 d. Analysis of variance-simultaneous component analysis is used to identify metabolites that distinguish exposed from control animals. Overall, alterations in lipid metabolism suggest the occurrence of oxidative stress in both the brain and the liver-a common adverse effect of xenobiotics. However, alterations in the amino acid arginine are also observed. These are likely related to the nitric oxide system that is known to be associated with the mechanism of action of antidepressants. In addition, changes in asparagine and methionine levels in the brain and pantothenate, uric acid, and formylisoglutamine/N-formimino-L-glutamate levels in the liver could indicate variation of amino acid metabolism in both tissues; and the perturbation of glutamate in the liver implies that the energy metabolism is also affected. These results reveal that environmentally relevant concentrations of amitriptyline perturb a fraction of the metabolome that is not typically associated with antidepressant exposure in fish. Environ Toxicol Chem 2019;00:1-13. © 2019 SETAC.

Effects of selected tricyclic antidepressants on early-life stages of common carp (Cyprinus carpio)

Despite the fact that pharmaceuticals occur in surface water in low concentrations, they can still have adverse effect on aquatic biota, because these substances are designed to have a specific mode of action even at low concentrations. To our knowledge, only little is known about the long-term effect of tricyclic antidepressant residues on non-target animals, especially fish. Hence, the aim of this study was to assess the effect of subchronic exposure to selected tricyclic antidepressants - namely, amitriptyline, nortriptyline, and clomipramine and their mixture - on early-life stages of common carp (Cyprinus carpio). Two embryo-larval toxicity tests with common carp were performed, each taking 30 days. For the experiment, three tricyclic antidepressants as well as their mixtures were tested at three different concentrations - 10, 100 and 500 μg/L. Hatching and mortality were recorded twice a day. In addition, samples were taken at regular intervals in order to record developmental stage, morphometric and condition characteristics and morphological anomalies. At the end of the test, additional samples were taken for histopathological examination and also for the determination of antioxidant and biotransformation enzyme activity and lipid peroxidation and protein carbonylation. Long-term exposure resulted in a significant increase in mortality, developmental retardation, morphological anomalies, and pathological changes in brain, heart, and cranial and caudal kidney. In addition, changes in antioxidant enzyme activity as well as increased lipid peroxidation were observed, even at the lowest tested concentrations. Hence, environmentally relevant concentrations of TCAs have the potential to cause harmful effects on early-life stages of fish.

Amitriptyline induces mitophagy that precedes apoptosis in human HepG2 cells

Systemic treatments for hepatocellular carcinoma (HCC) have been largely unsuccessful. This study investigated the antitumoral activity of Amitriptyline, a tricyclic antidepressant, in hepatoma cells. Amitriptyline-induced toxicity involved early mitophagy activation that subsequently switched to apoptosis. Amitriptyline induced mitochondria dysfunction and oxidative stress in HepG2 cells. Amitriptyline specifically inhibited mitochondrial complex III activity that is associated with decreased mitochondrial membrane potential (∆Ψm) and increased reactive oxygen species (ROS) production. Transmission electron microscopy (TEM) studies revealed structurally abnormal mitochondria that were engulfed by double-membrane structures resembling autophagosomes. Consistent with mitophagy activation, fluorescence microscopy analysis showed mitochondrial Parkin recruitment and colocalization of mitochondria with autophagosome protein markers.

Pharmacological or genetic inhibition of autophagy exacerbated the deleterious effects of Amitriptyline on hepatoma cells and led to increased apoptosis. These results suggest that mitophagy acts as an initial adaptive mechanism of cell survival. However persistent mitochondrial damage induced extensive and lethal mitophagy, autophagy stress and autophagolysome permeabilization leading eventually to cell death by apoptosis. Amitriptyline also induced cell death in hepatoma cells lines with mutated p53 and non-sense p53 mutation.

Our results support the hypothesis that Amitriptyline-induced mitochondrial dysfunction can be a useful therapeutic strategy for HCC treatment, especially in tumors showing p53 mutations and/or resistant to genotoxic treatments.

Effect of topical neuromodulatory medications on oral and skin keratinocytes

BACKGROUND

Neuromodulatory medications (NMs), such as amitriptyline, carbamazepine and gabapentin, are used as topical preparations for the management of neuropathic orofacial pain (NOP) and have produced promising preliminary results. The aim of this study was to investigate the effects of three aforementioned NMs on cell lines relevant to the orofacial tissues in vitro as no published studies have examined the effect of these topical NMs.

METHODS

Cellular viability was measured using alamarBlue^® , testing cumulative and specific time point effects of NMs on human skin keratinocytes and oral keratinocytes. Effects of the NMs on cell counts were investigated by CCK-8 assay. Drug concentrations released from NM orabase pastes after 30-min incubation were measured by high-performance liquid chromatography. Using these clinical concentrations, morphological changes and cytokine expression were investigated using scanning electron microscopy (SEM) and human inflammatory antibody array (AAH), respectively.

RESULTS

Cumulative and specific time point viability and cell count methods revealed that amitriptyline caused a significant decrease in cellular viability and counts in both cell lines. Carbamazepine also had significant effects after long-term exposure and at higher concentrations, whilst gabapentin had little demonstrable effect. SEM confirmed the cytotoxicity of amitriptyline, whilst AAH revealed no significant changes in cytokine expression following amitriptyline, carbamazepine or gabapentin exposure compared with control.

CONCLUSIONS

The results raise concerns about the safety of topical amitriptyline as it was cytotoxic to skin and oral keratinocytes in both exposure times and concentrations, whilst carbamazepine was cytotoxic only at high concentrations and after longer exposure times and gabapentin had no demonstrable effects.

Growth inhibition and coordinated physiological regulation of zebrafish (Danio rerio) embryos upon sublethal exposure to antidepressant amitriptyline

Amitriptyline is a tricyclic antidepressant used for decades. It is present at low detectable concentrations in the aquatic environment, but relative few studies have focused on its ecotoxicological effects on non-target aquatic animals. The present study conducted an acute toxicity test of waterborne amitriptyline exposure using zebrafish (Danio rerio) embryos 4 to 124 h-post-fertilization. Time-dependent lethal concentrations were firstly determined and at mg/L levels. Effects of amitriptyline on zebrafish embryos were then evaluated under amitriptyline exposure at sublethal concentrations of 1, 10, 100 ng/L, 1, 10, 100 μg/L and 1mg/L. Our results showed that amitriptyline significantly reduced the hatching time and body length of embryos after exposure in a concentration-dependent manner. Our study also revealed that the exposure evoked a coordinated modulation of physiological and biochemical parameters in exposed zebrafish embryos, including alterations of adrenocorticotropic hormone (ACTH) level, oxidative stress and antioxidant parameters, as well as nitric oxide (NO) production and total nitric oxide synthase (TNOS) activity. A U-shaped concentration-dependent response curve was observed in ACTH level in response to amitriptyline exposure. However, both U-shaped and inversed U-shaped curves were indicated in the responses of antioxidant parameters, including total antioxidant capacity, antioxidant enzyme activities (catalase, superoxide dismutase and peroxidase), glutathione content and glutathione reductase activity. Correspondingly, hydroxyl radical formation and lipid peroxidation indices changed in similar U-shaped concentration-dependent patterns, which together the results of antioxidant parameters suggested induction of oxidative stress in embryos exposed to amitriptyline at high concentrations. Moreover, NO production and TNOS activity were both significantly affected by amitriptyline exposure. Notably, significant correlations between these measured parameters were revealed, which suggested a dynamic adaptation process and coordinated regulation of multiple physiological systems in fish embryos to amitriptyline treatment. Furthermore, our study demonstrated that the effective concentrations of amitriptyline for measured parameters in zebrafish embryos were as low as 10 ng/L, and thus revealed the potential risk of amitriptyline and other antidepressants to aquatic life.

Amitriptyline aggravates the fibrosis process in a rat model of infravesical obstruction

Infravesical obstruction (IVO) secondary to benign prostatic hypertrophy can affect up to 50% of men over 50 years old and may cause serious and irreversible alterations throughout the urinary tract, especially in the bladder. Therapeutic approaches are currently limited. Amitriptyline has recently been described as an analgesic, anti-inflammatory and myorelaxant in some experimental models. The objective of this study was to investigate the effects of amitriptyline hydrochloride on the process of fibrosis in a bladder outlet obstruction model in rats. Male Wistar rats were subjected to IVO and studied at intervals of 1 and 14 days postprocedure. The rats were randomly divided into five groups: sham, IVO1-T, IVO1-NT, IVO14-T and IVO14-NT. Bladder tissue was processed for histopathology, immunohistochemistry and RT-PCR. The IVO14 groups presented bladder fibrosis, smooth muscle cell hypertrophy and bladder wall thickening. The IVO14-T group demonstrated a higher intensity of fibrosis, higher macrophage infiltration rate and higher gene expression of Transforming growth factor (TGF) Tgf-β1. Thus this data shows that in this experimental mode amitriptyline had an amplifying effect on the process of fibrosis as a whole.

Antidepressant drugs diversely affect autophagy pathways in astrocytes and neurons--dissociation from cholesterol homeostasis

In the search for antidepressants' (ADs') mechanisms of action beyond their influence on monoaminergic neurotransmission, we analyzed the effects of three structurally and pharmacologically different ADs on autophagic processes in rat primary astrocytes and neurons. Autophagy has a significant role in controlling protein turnover and energy supply. Both, the tricyclic AD amitriptyline (AMI) and the selective serotonin re-uptake inhibitor citalopram (CIT) induced autophagy as mirrored by pronounced upregulation and cellular redistribution of the marker LC3B-II. Redistribution was characterized by formation of LC3B-II-positive structures indicative of autophagosomes, which associated with AVs in a time-dependent manner. Deletion of Atg5, representing a central mediator of autophagy in MEFs, led to abrogation of AMI-induced LC3B-I/II conversion. By contrast, VEN, a selective serotonin and noradrenaline reuptake inhibitor, did not promote autophagic processes in either cell type. The stimulatory impact of AMI on autophagy partly involved class-III PI3 kinase-dependent pathways as 3-methyladenine slightly diminished the effects of AMI. Autophagic flux as defined by autophagosome turnover was vastly undisturbed, and degradation of long-lived proteins was augmented upon AMI treatment. Enhanced autophagy was dissociated from drug-induced alterations in cholesterol homeostasis. Subsequent to AMI- and CIT-mediated autophagy induction, neuronal and glial viability decreased, with neurons showing signs of apoptosis. In conclusion, we report that distinct ADs promote autophagy in neural cells, with important implications on energy homeostasis.

Acute oxidant damage promoted on cancer cells by amitriptyline in comparison with some common chemotherapeutic drugs

Oxidative therapy is a relatively new anticancer strategy based on the induction of high levels of oxidative stress, achieved by increasing intracellular reactive oxygen species (ROS) and/or by depleting the protective antioxidant machinery of tumor cells. We focused our investigations on the antitumoral potential of amitriptyline in three human tumor cell lines: H460 (lung cancer), HeLa (cervical cancer), and HepG2 (hepatoma); comparing the cytotoxic effect of amitriptyline with three commonly used chemotherapeutic drugs: camptothecin, doxorubicin, and methotrexate. We evaluated apoptosis, ROS production, mitochondrial mass and activity, and antioxidant defenses of tumor cells. Our results show that amitriptyline produces the highest cellular damage, inducing high levels of ROS followed by irreversible serious mitochondrial damage. Interestingly, an unexpected decrease in antioxidant machinery was observed only for amitriptyline. In conclusion, based on the capacity of generating ROS and inhibiting antioxidants in tumor cells, amitriptyline emerges as a promising new drug to be tested for anticancer therapy.

Increased mitochondrial superoxide dismutase expression and lowered production of reactive oxygen species during rotavirus infection

Rotaviruses are responsible for severe diarrhea in infants and substantial economic losses in animal husbandry worldwide. We investigated the oxidant/antioxidant status in rotavirus-infected human colon adenocarcinoma (Caco-2) cell line. Our results show that within the initial 48 h of infection the expression of the mitochondrial superoxide dismutase (MnSOD) is significantly increased, which correlates with a decrease in reactive oxygen species production, and with a lack of cellular glutathione depletion. During this period the mitochondria display a hyperpolarization of the inner membrane, which leads to an increased mitochondrial membrane potential. No increase in apoptosis was detected in the infected cultures. In contrast to many viral infections which cause redox imbalance in host cells, the described virus-host interaction suggests that rotavirus infection does not lead to an induction of oxidative stress, possibly to prolong cell survival and to allow for accumulation of viral particles before cell destruction and virus release.