Could agomelatine be the ideal antidepressant?

Depressive disorders are a common cause of chronic and recurrent psychiatric dysfunction, constituting the fourth leading cause of global diseases. Depression is associated with a high rate of morbidity and mortality, and is a leading cause of global disability. Despite the effectiveness of most currently available antidepressants, many of them have a number of undesirable side effects. Agomelatine is the first melatonin (MT)(1)/MT(2) agonist having 5-hydroxytryptamine (5-HT)(2C) and 5-HT(2B) antagonist properties and antidepressant activity. Agomelatine is effective in several animal models of depression and anxiety. In addition, three large, multicenter, multinational, placebo-controlled studies and several double-blind, placebo-controlled trials of agomelatine have demonstrated that it is a clinically effective and well-tolerated antidepressant in acute trials. Since currently available antidepressants are not always adequate to cause complete remission of symptoms in severely depressed patients, the superior rate of response achieved with agomelatine in this group of patients underlines its future for clinical use in depressive disorders. In summary, the clinical advantage of agomelatine is attributed to its novel mechanism of action, which helps not only to exert antidepressant action, but also to regulate the sleep-wake rhythm.

Is there a role for agomelatine in the treatment of anxiety disorders?A review of published data

Anxiety disorders (Ads) are the most common type of psychiatric disorders, Pharmacologic options studied for treating ADs may include benzodiazepines, tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRIs), noradrenergic and specific serotonergic antidepressants (NaSSA) and serotonin and noradrenaline reuptake inhibitors (SNRIs). Agomelatine, a new melatonergic antidepressant, has been shown effective in various types of mood disorders. Moreover, some evidence points towards a possible efficacy of such a drug in the treatment of ADs. Therefore, the aim of this review was to elucidate current (facts and views) data on the role of agomelatine in the treatment of ADs. The trials evaluating agomelatine in the treatment of generalized anxiety disorder are few but, overall, encouraging in regards to its efficacy. However, further randomized, placebo-controlled studies on larger samples use are needed. Apart from some interesting case reports, no large studies are, to date, present in literature regarding agomelatine in the treatment of other ADs, such as panic disorder, social anxiety disorder, obsessive-compulsive disorder and post-traumatic stress disorder. Therefore, the clinical efficacy and the relative good tolerability of agomelatine in generalized anxiety (GAD) warrants further investigation in ADs.

Melatonin and its agonists in pain modulation and its clinical application

Melatonin, the hormone of darkness has many physiological functions in the body and also exerts a number of pharmacological effects. Most of these actions of melatonin are mediated through melatonin membrane receptors like MT1/MT2 receptors or through nuclear orphan receptors like RZR/ROR receptors or through calcium binding proteins in the cytosol. The finding that pain perception is circadian in nature has prompted many to suggest that "pain modulation" is one of the most important physiological functions of melatonin. By using a number of animal models of pain perception, it has been found that melatonin exerts antinociceptive and antiallodynic effects. Number of studies has shown that melatonin modulates pain perception by acting through opioid receptors, NMDA receptors and G-protein, and they have been analyzed using specific antagonists like naloxone or NMDA-G protein receptor antagonists. Recently it has been shown that melatonin exerts its antinociceptive effects through MT1 and MT2 melatonergic receptors located in the dorsal region of the spinal cord as well as in various parts of the brain concerned with pain modulation. Evidences for this have been obtained by using common melatonergic receptor antagonist like luzindole or specific MT2 receptor antagonist like 4P-PDOT or K-185. In a few clinical studies undertaken during surgery, melatonin has been shown to have analgesic effects. Melatonin is emerging as a new analgesic drug with a novel mechanism of actions and has the potential to be used as a natural pain killer in inflammatory, neuropathic pain conditions and also during surgical procedures.

Mechanism of radioprotection by δ-tocotrienol: pharmacokinetics, pharmacodynamics and modulation of signalling pathways

OBJECTIVE

The objective of this study was to investigate the correlation between in vivo δ-tocotrienol (DT3) pharmacokinetics, pharmacodynamics and radiation protection, and to evaluate the effect of DT3 pre-treatment on radiation-induced alterations in apoptotic and autophagic pathways.

METHODS

We evaluated pharmacokinetics (plasma, 0.5 to 12 h) and pharmacodynamics (peripheral blood indices; day 3, 7, 10 and 14) after a single subcutaneous injection of 300 mg kg(-1) DT3 in unirradiated CD2F1 mice. Next, we monitored 30-day post-irradiation survival (9.25 Gy) and haematopoietic recovery of DT3-treated mice (7 Gy) exposed to cobalt-60 γ-irradiation. The effects of DT3 on irradiated bone marrow apoptosis and autophagy were determined by analyses of key caspases (3, 7, 9 and 8), beclin-1 and light chain 3 conversion.

RESULTS

Plasma concentration of DT3 reached ∼195 µM (Cmax) 1 h after injection (Tmax), and DT3 was eliminated from plasma 12 h later. In unirradiated mice, DT3 significantly increased white blood cells (WBCs), neutrophils, lymphocytes (day 3 post DT3 injection) and platelets (day 7) by 1.5- to 2-fold, over vehicle-treated control. DT3 pre-treatment improved 30-day survival to 100% (∼15% in control) and accelerated recovery of reticulocytes, platelets, WBCs, neutrophils, lymphocytes and monocytes in peripheral blood. DT3 reduced activation of caspase-8, caspase-3 and caspase-7, inherent to apoptosis, while increasing autophagy-related beclin-1 expression in irradiated bone marrow.

CONCLUSION

These data indicate that DT3 stimulates multilineage haematopoiesis, protects against radiation-induced apoptosis downstream of the mitochondria and stimulates cytoprotective autophagy. Apart from a potent antioxidant activity, DT3 may elicit survival advantage following irradiation by enhancing haematopoiesis and modulating signalling pathways.

Analgesic effects of codeine-6-glucuronide after intravenous administration

Centrally administered codeine glucuronide has been shown to exhibit antinociceptive properties with decreased immunosuppressive effects compared to codeine. In this study, codeine-6-glucuronide was administered to rats, and its analgesic effect was compared to that of codeine. The concentrations of codeine and its metabolites in plasma and brain were also determined at the peak response time after administration of each compound. Receptor-binding studies with rat brain homogenates and affinity profiles were also determined. Intravenous administration of codeine-6-glucuronide resulted in approximately 60% of the analgesic response elicited by codeine itself. Analysis of plasma and brain showed that codeine-6-glucuronide is relatively stable in vivo, with only small amounts of morphine-6-glucuronide being detected in addition to unchanged codeine-6-glucuronide. The receptor affinity of codeine-6-glucuronide was similar to that of codeine. It is concluded that intravenously administered codeine-6-glucuronide possesses analgesic activity similar to that of codeine, and may have clinical benefit in the treatment of pain

Severe reaction to radiotherapy for breast cancer as the presenting feature of ataxia telangiectasia

Background:

Severe early and late radiation reaction to radiotherapy is extremely rare in breast cancer patients. Such a reaction prompted an investigation into a 44-year-old mother (patient A-T213).

Methods:

A neurological examination was performed and blood lymphocytes and skin fibroblasts were assessed for radiosensitivity chromosomally and by colony-forming assay. The ATM gene was sequenced and ATM mutations modelled by site-directed mutagenesis. The ATM kinase activity was also assessed.

Results:

Patient A-T213 was normally ambulant with no ataxia and minimal other neurological features. T lymphocytes and skin fibroblasts were unusually radiosensitive, although less sensitive than in classical ataxia telangiectasia (A-T). A lymphoblastoid cell line and skin fibroblasts expressed ATM protein with some retained kinase activity. One missense ATM mutation c.8672G>A (p.Gly2891Asp) and a c.1A>G substitution were identified. In the modelling system, the p.Gly2891Asp mutant protein was expressed and shown to have residual ATM kinase activity.

Conclusion:

Patient A-T213 has a milder form of A-T with biallelic ATM mutations, which may have contributed to breast cancer development, and certainly caused the severe radiation reaction. Ataxia telangiectasia should be investigated as a potential cause of untoward severe early and late radiation reactions in breast cancer patients.

Lymphoid tumours and breast cancer in ataxia telangiectasia; substantial protective effect of residual ATM kinase activity against childhood tumours

Background:

Immunodeficiency in ataxia telangiectasia (A-T) is less severe in patients expressing some mutant or normal ATM kinase activity. We, therefore, determined whether expression of residual ATM kinase activity also protected against tumour development in A-T.

Methods:

From a total of 296 consecutive genetically confirmed A-T patients from the British Isles and the Netherlands, we identified 66 patients who developed a malignant tumour; 47 lymphoid tumours and 19 non-lymphoid tumours were diagnosed. We determined their ATM mutations, and whether cells from these patients expressed any ATM with residual ATM kinase activity.

Results:

In childhood, total absence of ATM kinase activity was associated, almost exclusively, with development of lymphoid tumours. There was an overwhelming preponderance of tumours in patients <16 years without kinase activity compared with those with some residual activity, consistent with a substantial protective effect of residual ATM kinase activity against tumour development in childhood. In addition, the presence of eight breast cancers in A-T patients, a 30-fold increased risk, establishes breast cancer as part of the A-T phenotype.

Conclusion:

Overall, a spectrum of tumour types is associated with A-T, consistent with involvement of ATM in different mechanisms of tumour formation. Tumour type was influenced by ATM allelic heterogeneity, residual ATM kinase activity and age.

Real-time measurement of stress and damage evolution during initial lithiation of crystalline silicon

Crystalline to amorphous phase transformation during initial lithiation in (100) Si wafers is studied in an electrochemical cell with Li metal as the counter and reference electrode. During initial lithiation, a moving phase boundary advances into the wafer starting from the surface facing the lithium electrode, transforming crystalline Si into amorphous Li(x)Si. The resulting biaxial compressive stress in the amorphous layer is measured in situ, and it was observed to be ca. 0.5 GPa. High-resolution TEM images reveal a very sharp crystalline-amorphous phase boundary, with a thickness of ∼1  nm. Upon delithiation, the stress rapidly reverses and becomes tensile, and the amorphous layer begins to deform plastically at around 0.5 GPa. With continued delithiation, the yield stress increases in magnitude, culminating in a sudden fracture of the amorphous layer into microfragments, and the cracks extend into the underlying crystalline Si.

Melatonin agonists in primary insomnia and depression-associated insomnia: are they superior to sedative-hypnotics?

Current pharmacological treatment of insomnia involves the use of sedative-hypnotic benzodiazepine and non-benzodiazepine drugs. Although benzodiazepines improve sleep, their multiple adverse effects hamper their application. Adverse effects include impairment of memory and cognitive functions, next-day hangover and dependence. Non-benzodiazepines are effective for initiating sleep but are not as effective as benzodiazepines for improving sleep quality or efficiency. Furthermore, their prolonged use produces adverse effects similar to those observed with benzodiazepines. Inasmuch as insomnia may be associated with decreased nocturnal melatonin, administration of melatonin is a strategy that has been increasingly used for treating insomnia. Melatonin can be effective for improving sleep quality without the adverse effects associated with hypnotic-sedatives. Ramelteon, a synthetic analog of melatonin which has a longer half life and a stronger affinity for MT1 and MT2 melatonergic receptors, has been reportedly effective for initiating and improving sleep in both adult and elderly insomniacs without showing hangover, dependence, or cognitive impairment. Insomnia is also a major complaint among patients suffering from depressive disorders and is often aggravated by conventional antidepressants especially the specific serotonin reuptake inhibitors. The novel antidepressant agomelatine, a dual action agent with affinity for melatonin MT1 and MT2 receptors and 5-HT2c antagonistic properties, constitutes a new approach to the treatment of major depressive disorders. Agomelatine ameliorates the symptoms of depression and improves the quality and efficiency of sleep. Taken together, the evidence indicates that MT1/MT2 receptor agonists like ramelteon or agomelatine may be valuable pharmacological tools for insomnia and for depression-associated insomnia.

Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman, 13C, 1H and UV), first order hyperpolarizabilities, NBO and TD-DFT analysis of the 4-methyl-2-cyanobiphenyl

The Fourier transform infrared (FT-IR) and FT-Raman of 4-methyl-2-cyanobiphenyl (4M2CBP) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) method. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. The first order hyperpolarizability (β0) of this novel molecular system and related properties (β, α0 and Δα) of 4M2CBP are calculated using HF/6-311G(d,p) method on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* antibonding orbitals and second order delocalization energies (E2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) approach. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.