Probing novel compound classes & a new interacting protein for the Mammalian GАВА(_A) receptor

y-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate brain mediating its fast inhibitory action via GABA(_A) receptors. These receptors are implicated in a number of neurological diseases, making GABA(_A) receptor ligands interesting as potential therapeutic agents. The aims of this research project were two-fold: identifying leads for the discovery of new chemical entities that modify GABA(_A) receptor function. The second aim was to increase the understanding of GABAgeric transmission by studying the pharmacological influence of a new interacting protein for the mammalian GABA(_A) receptor, GRIF-1. In the search for novel ligands for GABA(_A) receptor, the pharmacology of three structurally distinct compound classes was investigated. The first class was the NSAID, Mefenamic acid (MFA) and a group of analogues. Results showed that MFA and a series of analogues selectively modulate GABAAR at the agonist binding site, but did not interact with either the picrotoxin or the benzodiazepine sites. Indeed the most significant result of this study was the identification of common active conformers of MFA compound and the differentiation of two analogues based on MFA structure, with an improvement in apparent efficacy. The second compound studied was Octyi-13-Dglucoside, a small molecule congener of a natural fungal metabolite, Caloporoside. These studies demonstrated that Octyi-13-D-glucoside is a positive modulator of GABAA receptor at the channel site demonstrated by its stimulation of specific [(^35)S] TBPS binding. The level of stimulation was similar to that elicited by diazepam and was occluded by GABA. Preliminary structure-activity study showed that the 13-glycosidic linkage and chain length are crucial for the positive modulation of [(^35)S] TBPS binding to the GABAAR by this novel chemical class. The third compound series were essential oils derived from Melissa officinalis and Lavendula angustifolia. These two oils either singly or in combination have been reported to have a significant benefit in the treatment of agitation in dementia. The purpose of this study was to clarify the sedative and calming mechanisms of these two common essential oils by investigating their effects on the GABAAR complex. Melissa and Lavender both singly and in combination inhibit [(^35)S] TBPS binding to the channel site of GABAAR. Melissa oil displayed the higher affinity. Melissa oil alone also showed a stimulatory effect on [(^3)H] muscimol binding. Interestingly, a combination effect on the inhibition of [(^3)H] flunitrazepam binding to the GABAAR has been shown when Lavender and Melissa oils are applied together (50:50), with no effect when applied alone. Neither Melissa nor Lavender oils demonstrated any effect on the binding of [(^3)H] MK-801 to NMDA receptors, or [3H) nicotine to nicotinic acetylcholine receptors. Furthermore, functional studies have demonstrated that both oils (0.01 mg/ml) applied to rat primary cortical neuron cultures, results in a significant reduction in both inhibitory and excitatory transmission, with a net depressant effect on neurotransmission. These data suggests that the calming/sedative effects of Melissa are mediated by multiple mechanisms in the CNS; the net effect is depressant on the overall neuronal network. Finally, a pharmacological study was performed on GRIF-1a, a novel GABAA receptor 132 subunit trafficking protein, to gain further insights into the potential role of this novel protein at the inhibitory synapse. In the present work, evidence was provided that GRIF-1a does not increase a1j32y2 receptor complex numbers, but appears importantly to stabilise the GABAAR in a conformation which facilitates binding to both GABA and benzodiazepines. These findings suggest that GRIF-1 protein may be a novel means of modifying the efficacy of synaptic inhibition. In summary, this thesis provides a clear picture about four novel ways for the modulation of the GABAA receptor inhibitory transmission

New Insights Into the Anticonvulsant Effects of Essential Oil From Melissa officinalis L. (Lemon Balm)

Melissa officinalis L. is used in traditional European and Iranian folk medicines to treat a plethora of neurological diseases including epilepsy. We utilized the in vitro and in vivo models of epilepsy to probe the anticonvulsant potentials of essential oil from M. officinalis (MO) to gain insight into the scientific basis for its applications in traditional medicine for the management of convulsive disorders. MO was evaluated for effects on maximal electroshock (MES) and pentylenetetrazole (PTZ) -induced seizures in mice, on 4–aminopyridine (4-AP)-brain slice model of epilepsy and sustained repetitive firing of current clamped neurons; and its ameliorative effects were examined on seizure severity, anxiety, depression, cognitive dysfunction, oxidative stress and neuronal cell loss in PTZ-kindled rats. MO reversibly blocked spontaneous ictal-like discharges in the 4-AP-brain slice model of epilepsy and secondary spikes from sustained repetitive firing, suggesting anticonvulsant effects and voltage-gated sodium channel blockade. MO protected mice from PTZ– and MES–induced seizures and mortality, and ameliorated seizure severity, fear-avoidance, depressive-like behavior, cognitive deficits, oxidative stress and neuronal cell loss in PTZ–kindled rats. The findings warrant further study for the potential use of MO and/or its constituent(s) as adjunctive therapy for epileptic patients

Targeting dopaminergic system for treating nicotine dependence

Background: Smoking is the world's leading cause of preventable death among populations. Cigarette smoking increases the risk of numerous health problems, including heart diseases, stroke, atherosclerosis and many types of cancer, including lung, stomach and bladder cancers. Outcomes: Many individuals find it difficult to stop smoking because of the addictive effects of nicotine and the presence of several monoamine oxidase (MAO) inhibitors in the tobacco smoke extract. Objective: The development of novel, safe and effective medications for smoking cessation is a high public health priority. Results: The role of mesocorticolimbic dopaminergic pathways in withdrawal symptoms and general reinforcement processes clearly recommends dopaminergic system as a potential target for the treatment of nicotine addiction. Conclusion: This review article discusses the new pharmacological treatments of nicotine dependence, which are targeting dopaminergic neurotransmission. This includes blockade of dopamine transporter and inhibition of MAO as pharmacotherapy for the treatment of nicotine dependence. 2016 Bentham Science Publishers.Scopu

Knowledge of and Attitude towards Epilepsy among the Jordanian Community

Background: Epilepsy is a disorder characterized by recurring seizures that do not have an immediate identifiable cause. It is a disorder with complex symptoms and a wide range of risk factors, with age, genetics, and origin being the most prevalent variations. This study aimed to evaluate the knowledge of and attitude towards epilepsy among the Jordanian community. Method: An online cross-sectional study using a self-administered questionnaire was conducted between 29 March and 15 May 2022 in Jordan. In this study, three previously validated questionnaire items were adapted and employed. Binary logistic regression was applied to identify predictors of good knowledge and a positive attitude. Results: A total of 689 participants were involved in this study. A weak level of knowledge about epilepsy was observed among the study participants (35.3%). The participants showed a moderately positive attitude towards epilepsy (63.3%). Being female, holding a bachelor’s degree, knowing anyone who had epilepsy and seeing anyone having an epileptic seizure were factors that positively affected participants’ knowledge about epilepsy. Being aged between 24 and 29 years or being divorced were factors that affected the participants’ attitudes negatively towards epilepsy. Conclusion: The study’s participants had limited knowledge of epilepsy and a favorable attitude toward it. The community’s understanding of epilepsy and attitude toward epilepsy patients should be improved by an informed educational effort on the part of various media platforms. All facets of the community, including parents, should be the focus of these initiatives

Anti-convulsant Effects of Bongardia chrysogonum L. Tuber in the Pentylenetetrazole-induced Seizure Model

Background and Objective: The dried tuber of Bongardia chrysogonum (L.) is a popular folk remedy for its use in the treatment of epilepsy in traditional medicine. The study aimed to evaluate the anti-oxidant and anti-convulsant activity of B. chrysogonum ethanolic-aqueous extract using the Pentylenetetrazole (PTZ) kindling animal model. Materials and Methods: Male mice were randomly selected and divided into 9 experimental groups including: Control group, pentylenetetrazole kindled mice, positive mice group receiving valproate (200 mg kg–1 p.o.) a classic anticonvulsant drug and 3 groups receiving B. chrysogonum tuber-ethanolic or aqueous extract at a doses of (600, 900 and 1200 mg kg–1 p.o.). All groups, except the control, were kindled by 11 injections of PTZ (40 mg kg–1, i.p.). All groups, except the control group, were tested at 12th PTZ challenge dose (75 mg kg–1 i.p.). The exhibited phases of seizure (0-6) were observed and noted; moreover, anti-oxidant effect of these extract was examined in in vitro study by using a spectrophotometric technique. The significance of differences between groups were determined using one-way analysis of variance (ANOVA) followed by post hoc test, Dunnett’s multiple comparison tests. Results: The data showed that both valproate and B. chrysogonum tuber extracts delay the onset of convulsions, decrease duration of the seizure and reduced mortality significantly (p<0.05). In addition, B. chrysogonum showed a wide range of scavenging capacities for free radicals, which may underpin the effective in vivo seizure suppression. Conclusion: It was concluded that B. chrysogonum L. tuber extracts display anti-oxidant, free radical scavenging properties in vitro and, in mice, provides new scientific evidence for the anti-seizure properties of B. chrysogonum

Evaluation of the anti-nociceptive profile of essential oil from Melissa officinalis L. (lemon balm) in acute and chronic pain models

Ethnopharmacological relevanceMelissa officinalis L. (Lamiaceae) is a medicinal plant native to Mediterranean regions and found in other parts of the world. Extracts and essential oil from this widely cultivated culinary medicinal herb are used in traditional medicine to manage a variety of disorders that include epilepsy and pain.Aim of the studyTo assess the anti-nociceptive potentials of Melissa officinalis essential oil (MO) and probe the involvement of adrenergic, opioidergic, serotonergic and potassium adenosine triphosphate (KATP) mechanisms in its anti-nociceptive effects.Material and methodsWe employed formalin-, acetic acid and hot plate-induced nociception to study the acute anti-nociceptive effects of MO. The sciatic nerve injury (CCI) model of neuropathic pain was utilized to study the anti-nociceptive effects of MO on chronic pain. Effects of MO on anxiety, cognitive deficits, oxidative stress and inflammation in the CCI rats were evaluated on elevated plus maze, open field test, novel object recognition, oxidative stress parameters and pro-inflammatory cytokines, respectively. The possible mechanism(s) of MO's anti-nociceptive effects were elucidated using prazosin, yohimbine, propranolol, glibenclimide, naloxone and metergoline, which are acknowledged antagonists for α1–, α2– and β–adrenergic, potassium adenosine triphosphate (KATP), opioidergic and serotonergic systems, respectively.ResultsMO significantly attenuated acetic acid- and formalin-induced nociception; prolonged the mean reaction time of rats on hot plate before and following sciatic nerve chronic injury (CCI). MO ameliorated anxiety, cognitive deficits and oxidative stress, reduced pro-inflammatory cytokine levels and produced a near total restoration of injured sciatic nerves in CCI rats. Naloxone, metergoline and glibenclimide significantly blocked, while prazosin, yohimbine and popranolol failed to block the anti-nociceptive effects of MO in formalin-induced nociception.ConclusionsMO contains biologically active compounds with potential anti-nociceptive properties that modulate KATP, opioidergic and serotonergic pathways. These support the development of bioactive compounds from MO as anti-nociceptive agents