Promiscuous gating modifiers target the voltage sensor of K(v)7.2, TRPV1, and H(v)1 cation channels.

Some of the fascinating features of voltage-sensing domains (VSDs) in voltage-gated cation channels (VGCCs) are their modular nature and adaptability. Here we examined the VSD sensitivity of different VGCCs to 2 structurally related nontoxin gating modifiers, NH17 and NH29, which stabilize K(v)7.2 potassium channels in the closed and open states, respectively. The effects of NH17 and NH29 were examined in Chinese hamster ovary cells transfected with transient receptor potential vanilloid 1 (TRPV1) or K(v)7.2 channels, as well as in dorsal root ganglia neurons, using the whole-cell patch-clamp technique. NH17 and NH29 exert opposite effects on TRPV1 channels, operating, respectively, as an activator and a blocker of TRPV1 currents (EC50 and IC50 values ranging from 4 to 40 µM). Combined mutagenesis, electrophysiology, structural homology modeling, molecular docking, and molecular dynamics simulation indicate that both compounds target the VSDs of TRPV1 channels, which, like vanilloids, are involved in π-π stacking, H-bonding, and hydrophobic interactions. Reflecting their promiscuity, the drugs also affect the lone VSD proton channel mVSOP. Thus, the same gating modifier can promiscuously interact with different VGCCs, and subtle differences at the VSD-ligand interface will dictate whether the gating modifier stabilizes channels in either the closed or the open state.

Anxiolytic and antidepressants' effect of Crataegus pinnatifida (Shan Zha): biochemical mechanisms.

Depression and anxiety disorders are highly prevalent. Selective serotonin reuptake inhibitors (SSRIs) are the current first-line treatment for depression, but they have pronounced limitations. Traditional Chinese medicine can serve as a safe and effective alternative to conventional drugs, particularly since many herbal remedies have already been approved for human use as food additives, making the transition from bench to bedside more efficient. We previously demonstrated that a novel herbal treatment (NHT) induces anxiolytic- and antidepressant-like effects. NHT consists of four herbs: Crataegus pinnatifida (Shan Zha), Triticum aestivum (Fu Xiao Mai), Lilium brownii (Baihe), and the fruit of Ziziphus jujuba (Da Zao). In the current study, we examined the antidepressant-like and anxiolytic-like activities of each individual herb on stressed mice and compared those to the effects of NHT and escitalopram. We show here that Shan Zha is sufficient to produce an anxiolytic and antidepressant-like effect similar to NHT or the escitalopram through activation of 5-HT1A receptor and an elevation in BDNF levels in the hippocampus and Pre-frontal cortex (PFC). Chronic treatment with Shan Zha did not alter serotonin transporter levels in the PFC, as opposed to escitalopram treatment. These results were confirmed in vitro, as none of the herbs blocked SERT activity in Xenopus oocytes. Notably, Shan Zha is sold as a nutritional supplement; thus, its transition to clinical trials can be easier. Once its efficacy and safety are substantiated, Shan Zha may serve as an alternative to conventional antidepressants.

Altered affinity of the platelet vesicular monoamine transporter 2 to dihydrotetrabenazine in children with major depression.

Platelet vesicular monoamine transporter (VMAT2) binding characteristics were assessed, using high affinity dihydrotetrabenazine ([(3)H]TBZOH) binding, in 14 children with major depression (MDD) and 16 matched controls. All participants underwent a thorough diagnostic evaluation and the levels of depression and anxiety were measured. K (d) values were significantly lower in children with MDD versus controls (2.93 ± 0.84 vs. 3.63 ± 0.56 nM, respectively, t = 2.4, df = 18.4, p = 0.025). B (max) values did not differ significantly. This preliminary finding indicates a possible structural change in platelet VMAT2 in children with MDD.

Moderation of the transgenerational transference of antenatal stress-induced anxiety.

Maternal stress has debilitating implications for both mother and child, including increased risk for anxiety. The current COVID-19 pandemic escalates these phenomena, thus, urging the need to further explore and validate feasible therapeutic options. Unlike the protracted nature of clinical studies, animal models could offer swift evidence. Prominent candidates for treatment are selective serotonin reuptake inhibitors (SSRIs) to the mother, that putatively accommodate maternal functioning, and, thereby, also protect the child. However, SSRIs might have deleterious effects. It is important to assess whether SSRIs and other pharmacotherapies can moderate the transference of anxiety by soothing maternal anxiety and to examine the extent of offspring's exposure to the drugs via lactation. To our knowledge, the possibility that antenatal stress exacerbates lactation-driven exposure to SSRIs has not been tested yet. Thirty ICR-outbred female mice were exposed to stress during gestation and subsequently administered with either the SSRI, escitalopram, or the novel herbal candidate, shan-zha, during lactation. Upon weaning, both dams' and pups' anxiety-like behavior and serum escitalopram levels were assessed. The major findings of the current study show that both agents moderated the antenatal stress-induced transgenerational transference of anxiety by ameliorating dams' anxiety. Interestingly though, pups' exposure to escitalopram via lactation was exacerbated by antenatal stress. The latter finding provides a significant insight into the mechanism of lactation-driven exposure to xenobiotics and calls for a further consideration vis-à-vis the administration of other drugs during breastfeeding.

Lack of modulatory effect of short-term repeated electroconvulsive therapy on platelet vesicular monoamine transporter 2 (VMAT2) in depressed patients.

We investigated the effect of electroconvulsive therapy (ECT) on platelet vesicular monoamine-transmitter-transporter 2 (pVMAT2) using high-affinity [(3)H]dihydrotetrabenazine binding to platelet VMAT2 in 11 women and 7 men, aged 53.7 +/- 15.8. The Hamilton Depression Rating Scale (HAM-D) and the binding characteristic of pVMAT2 were assessed before and after six ECTs, administered over 21 days. A significant reduction (4.5 +/- 0.46; 20.8%) was obtained in HAM-D scores (p < 0.01) following the ECTs. The pVMAT2 density (B (max)) and affinity values (K (d)) remained unaltered. Six ECTs are not sufficient for modulation in pVMAT2 expression. Long-term studies are needed to clarify the relationship between full remission and possible alterations in platelet/brain VMAT2 characteristics.

Dissociation between rewarding and psychomotor effects of opiates: differential roles for glutamate receptors within anterior and posterior portions of the ventral tegmental area.

The rewarding effects of drugs of abuse are thought to be dependent on the mesocorticolimbic dopamine system, which originates in the ventral tegmental area (VTA) and projects into the nucleus accumbens (NAC) and other forebrain regions. Heroin, by inhibiting GABAergic interneurons in the VTA, induces local dopaminergic activation and release in the NAC terminals. The role of other basic neurotransmitter systems, such as glutamate in the VTA, in mediating the rewarding effect of addictive drugs, is less established. We explored whether blockade of glutamate receptors in subregions of the VTA modulate the rewarding properties and/or the development of psychomotor changes induced by opiates. Administration of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; an AMPA/kainate receptor antagonist) into the anterior VTA blocked the rewarding effects of opiates in both the conditioned place preference and the self-administration paradigms without affecting the gradual increase of the psychomotor response to opiates. In contrast, administration of CNQX into the posterior VTA did not affect the rewarding properties of opiates, but blocked the initial sedative effect of opiates and the gradual increase of the psychomotor response to the drug. These findings suggest a critical role for glutamate receptors in the VTA in opiate reward, as well as behavioral and anatomical dissociation between the rewarding and psychomotor effects of opiates.

Cerebral MAO Activity Is Not Altered by a Novel Herbal Antidepressant Treatment.

Inhibition of monoamine oxidase (MAO)-A/B can ameliorate depressive- and anxiety-related symptoms via increase of monoamine extracellular levels. However, such inhibition can also instigate hypertensive response following exposure to dietary tyramine (i.e., "the cheese effect"). Novel herbal treatment (NHT) is an herbal formula that has been demonstrated to reduce depressive- and anxiety-like symptoms in pre-clinical studies. The aim of the current study was to examine whether the therapeutic potential of NHT is underlain by inhibition of MAO-A/B and whether NHT poses a risk for tyramine hyper-potentiation. Unpredictable chronic mild stress (UCMS)-exposed mice and naïve mice were treated for 3 weeks with NHT (30 mg/kg; i.p.), the selective serotonin reuptake inhibitor (SSRI) escitalopram (15 mg/kg; i.p.), or saline. Subsequently, MAO-A/B activities in the hypothalamus, striatum, and prefrontal cortex (PFC) were assessed. Exposure to UCMS led to significant increases in both MAO-A and MAO-B activities in the hypothalamus (p < 0.001) and in the PFC (p < 0.01 for MAO-A; p < 0.001 for MAO-B). Neither NHT nor escitalopram had any notable effects. Treatment with NHT was supported as safe in terms of risk for inducing a hypertensive response. The antidepressant- and anxiolytic-like effects of NHT are mediated via pathways other than MAO-A/B inhibition.

Involvement of pituitary adenylate cyclase activating polypeptide (PACAP) and its receptors in the mechanism of antidepressant action.

Recent studies have suggested antidepressant involvement in synaptic plasticity, possibly mediated by neurotrophins and neuropeptides. Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide and neuromodulator. Since its discovery, PACAP has been extensively investigated with regard to its neurotrophic properties including regulation of brain-derived neurotrophic factor (BDNF) expression, a neurotrophin postulated to be involved in the mechanism of antidepressant action and etiology of affective disorders. Using real-time polymerase chain reaction (PCR) technique, we demonstrate in this paper a robust upregulation of BDNF messenger RNA (mRNA) expression in rat primary cortical neurons following a 6-hour incubation with PACAP, and subsequently elevated BDNF expression after prolonged treatment. Additional experiments were conducted to evaluate the effects of antidepressants on the expression of PACAP, its receptors and BDNF. In rat hippocampal neurons, prolonged (72-hour) treatment with selective serotonin reuptake inhibitors paroxetine and citalopram significantly up-regulated BDNF and PACAP expression and down-regulated PACAP receptor (PAC1 and VPAC2) expression; the tricyclic antidepressant imipramine had an opposite effect. These alterations in BDNF expression correlated negatively with PAC1 and VPAC2 expression, and positively with PACAP mRNA levels. Thus, our findings suggest the possible involvement of PACAP signaling in the neuronal plasticity induced by antidepressant treatment.

GABAA Receptor Density Is Not Altered by a Novel Herbal Anxiolytic Treatment.

Anxiety disorders are highly prevalent and considered a major public health concern worldwide. Current anxiolytics are of limited efficacy and associated with various side effects. Our novel herbal treatment (NHT), composed of four constituents, was shown to reduce anxiety-like behavior while precluding a common side effect caused by current anxiolytics, i.e., sexual dysfunction. Nevertheless, NHT's mechanism of action is yet to be determined. There is evidence that some medicinal herbs interact with the GABAergic system. Therefore, we aimed to examine whether NHT's anxiolytic-like effect is exerted by alterations in GABAA receptor density in the hippocampus, prefrontal cortex, and hypothalamus. The effects of 3-weeks treatment with NHT on anxiety-like behavior and locomotion were assessed using the elevated plus maze (EPM) and the open field test (OFT), respectively. Regional GABAA receptor levels were analyzed using [3H] RO15-1788 high-affinity binding assays. In stressed mice, NHT reduced anxiety-like behavior similarly to the benzodiazepine, clonazepam, while locomotion remained intact. Lack of changes or minor changes in regional GABAA receptor density in the brain were induced by NHT or clonazepam. In naive mice, performance in the EPM, locomotion and GABAA receptor densities were not altered by treatment with NHT or clonazepam. These findings support NHT as an efficacious and safe anxiolytic, although the GABAergic involvement remains to be further elucidated.

Reduced platelet vesicular monoamine transporter density in Tourette's syndrome pediatric male patients.

The vesicular monoamine transporter (VMAT2) plays a major role in the synaptic accumulation and quantal release of monoamines. In this study, we assessed high affinity [(3)H]dihydrotetrabenazine binding to platelet VMAT2, in a group of untreated male Tourette's syndrome (TS) patients (age: 8-17.5 years, n=9) and in a group of age- and sex-matched healthy controls (age: 9-16 years, n=16). Significantly decreased platelet VMAT2 density (B(max)) (-23%, p=0.016) was observed in the TS patients. The affinity (K(d)) of the ligand to platelet VMAT2 was similar in both groups. If the lower platelet VMAT2 density also occurred in the brain, it may have serve as an adaptive mechanism geared to decrease dopamine storage in the presynaptic neurons and thereby to attenuate the dopaminergic overactivity and ameliorate the movement disorder.

Serotonin uptake to lymphocytes of patients with social phobia compared to normal individuals.

Several trials have indicated that selective serotonin reuptake inhibitors (SSRIs) are most efficient in the treatment of social phobia (SP). The activity of the serotonin transporter (5-HTT), as determined by [3H]5-HT uptake to blood lymphocytes, was measured in 15 drug-free patients with generalized SP (7M/8F, aged 21-37 years) and compared to 18 healthy control subjects (10M/8F, aged 21-32 years). The maximum uptake velocity (Vmax) of [3H]5-HT to fresh lymphocytes and the affinity (Km) of the 5-HTT were similar in the two groups (295+/-155 versus 227+/-117 pmol/min/mg protein and 767+/-425 versus 709+/-408 nM, respectively). This study suggests that the functioning of lymphocyte 5-HTT is unaltered in SP.

Characterization of the serotonin transporter in lymphocytes and platelets of schizophrenia patients treated with atypical or typical antipsychotics compared to healthy individuals.

A rapidly growing body of data suggests that abnormalities in serotonergic function might be involved in the pathophysiology of schizophrenia and that serotonergic mechanisms play a role in the therapeutic effects of antipsychotics. The activity of the serotonin transporter (5-HTT), as determined by [(3)H]5-HT uptake to blood lymphocytes, was measured in 38 medicated schizophrenia patients (15 of them treated with typical antipsychotics and 23 treated with atypical antipsychotics) and 15 healthy control subjects. In addition, the pharmacodynamic characteristics of platelet 5-HTT were assessed by [(3)H]citalopram binding. There were no significant differences in the density (B(max)) of platelet [(3)H]citalopram binding sites between the three groups. Similarly, the dissociation constant (K(d)) values were indistinguishable. There were no significant differences in the maximal uptake velocity (V(max)) of [(3)H]5-HT to fresh lymphocytes between the three groups. The affinity (K(m)) values of 5-HT to the 5-HTT were significantly higher in schizophrenia patients treated with typical antipsychotics compared with control subjects. The K(m) values in schizophrenia patients treated with atypical antipsychotics were significantly lower compared with those observed in the group of schizophrenia patients treated with typical antipsychotics; however, they were comparable to values in the control group. The high values of K(m) associated with typical antipsychotic treatment may be relevant to the high risk of developing extrapyramidal side effects (EPS). The role of the various components of the serotonergic system in the etiopathology of schizophrenia and the mechanisms by which antipsychotics achieve their therapeutic effects need to be further evaluated.

Serotonin transporter characteristics in lymphocytes and platelets of male aggressive schizophrenia patients compared to non-aggressive schizophrenia patients.

A large body of literature indicates that disturbances of central serotonin (5-HT) function play an important role in aggressive behavior. Results from open-label and placebo-controlled trials as well as the reported inverse relationship between 5-HT function and aggression in human subjects, suggest that reduced 5-HT activity is associated with aggressive behavior. The activity of the 5-HT transporter (5-HTT), as determined by [(3)H]5-HT uptake to blood lymphocytes, was measured in 20 currently aggressive and 20 non-aggressive male schizophrenia patients. In addition, the pharmacodynamic characteristics of platelet 5-HTT were assessed by [(3)H]citalopram binding. There were no significant differences in the density (B(max)) of platelet [(3)H]citalopram binding sites between the two groups. Similarly, the dissociation constant (K(d)) values were indistinguishable. The maximum uptake velocity (V(max)) of [(3)H]5-HT to fresh lymphocytes and the K(m) values of the 5-HT to the transporter were significantly higher in currently aggressive compared to the non-aggressive schizophrenia patients. The association of high V(max) values with current aggressive behavior provides further support to the involvement of the 5-HTT in aggressive behavior as well as to the efficacy of 5-HTT blockers in the control of aggression. The role of the various components of the serotonergic system in the pathophysiology and treatment of aggressive behavior in schizophrenia needs to be further evaluated.

Education: Teaching pharmacogenomics to prepare future physicians and researchers for personalized medicine.

The vision of personalized medicine, the practice of medicine where each patient receives the most appropriate medical treatments and the most fitting dosage and combination of drugs based on his or her genetic make-up, seems to become more realistic as our knowledge about the human genome rapidly expands. We already know the reason for many types of adverse drug reactions, which are often related to polymorphic gene alleles of drug metabolizing enzymes. Moreover, insight into reasons for poor drug efficacy, often related to single nucleotide polymorphisms or larger polymorphisms in genes encoding drug target proteins, has been gained. There is a growing need to incorporate this increasingly complex body of knowledge to the standard curriculum of medical schools, so that the forthcoming generation of clinicians and researchers will be familiar with the latest developments in pharmacogenomics and medical bioinformatics, and will be capable of providing patients with the expected benefits of personalized medicine.

Repeated swim stress leads to down-regulation of vesicular monoamine transporter 2 in rat brain nucleus accumbens and striatum.

We assessed the impact of chronic swim stress in rats (daily for 3 weeks) on vesicular monoamine transporter 2 (VMAT2) in the nucleus accumbens and striatum. Exposure to repeated swim stress resulted in significant reduction in VMAT2 density in nucleus accumbens (20%, p<0.01) and striatum subregions (21-38%, p<0.001). The down-regulation of VMAT2 in this dopaminergic regions may serve as an adaptatory mechanism in the response to prolonged stress, and may be relevant to chronic stress-induced depression.

Decreased platelet vesicular monoamine transporter density in habitual smokers.

The brain vesicular monoamine transporter (VMAT2) is part of the re-uptake mechanism which regulates monoaminergic neurotransmission. We demonstrated previously a high degree of similarity between the pharmacodynamic characteristics of platelet and brain VMAT2. Nicotine induced increase of dopamine and serotonin neurotransmission in limbic structures may alter the expression of VMAT2 in brains of smokers. In this study we measured the VMAT2 pharmacodynamic characteristics using high-affinity [3H]dihydrotetrabenazine (TBZOH) binding to platelets of smokers (n=15) compared to sex and age matched healthy nonsmokers controls (n=14). A significant decrease (17%, P=0.02) in VMAT2 density (Bmax) was observed in platelets of smokers compared to nonsmokers. There was no significant difference in the affinity of [3H]TBZOH to its platelet binding site and the VMAT2 density did not correlate with the heaviness of smoking. The decreased density of the VMAT2 in the platelets of smokers may reflect nicotine induced desensitization of VMAT2, a phenomenon that may be relevant to the addictive properties of nicotine.

Decreased platelet vesicular monoamine transporter density in children and adolescents with attention deficit/hyperactivity disorder.

The aim of the present study was to assess vesicular monoamine transporter (VMAT2) density in attention deficit/hyperactivity disorder (ADHD), a disorder involving monoaminergic dysregulation. It was hypothesized that the hypoactivity of monoaminergic neurotransmission related to ADHD could be associated with an under-expression of VMAT2. We assessed high affinity [3H]dihydrotetrabenazine [TBZOH] binding to platelet VMAT2 in untreated male ADHD children and adolescents (n=11) as compared to age-matched controls (n=14), as well as the correlation between VMAT2 density and the severity of ADHD symptoms as measured by the clinician-administered DSM-IV ADHD Scale (DAS) and the parent-administered Abbreviated Conners' Rating Scale (ACPRS). The [3H]TBZOH binding capacity (Bmax) was significantly lower (17%) in the ADHD group as compared to the controls. There was no difference between the two groups in the affinity (Kd value) of [3H]TBZOH to its binding site. An inverse correlation was found between the ADHD symptom scales and the Bmax values. It remains unclear whether the under-expression of platelet VMAT2 in ADHD children is reflective of a parallel change in the brain, and whether it is primary or an epiphenomenon of ADHD.

Reduced platelet vesicular monoamine transporter density in smoking schizophrenia patients.

Brain vesicular monoamine transporter 2 (VMAT2) has a critical role in the regulation of monoaminergic neurotransmission. In our previous study we have found decreased platelet VMAT2 density in healthy habitual smokers. Schizophrenia is associated with high rate of cigarette smoking. In the present study we assessed platelet VMAT2 pharmacodynamic characteristics in a population of medicated schizophrenia patients (n=36) comparing smokers (n=23) vs. non-smokers (n=13). A significant decrease in platelet VMAT2 density (24%, p=0.005) was found in the smokers compared to the non-smokers . This decrease was not ascribed to the pharmacotherapy. An inverse correlation was found in the smokers between the platelet VMAT2 density and the severity of schizophrenia as assessed by the positive and negative syndrome scale (PANSS). Our observation in schizophrenia patients is consistent with that found in healthy smokers. The complex relationship between VMAT2 expression, cigarette smoking and schizophrenia merits a further large scale study.

Platelet vesicular monoamine transporter density in untreated patients diagnosed with social phobia.

The vesicular monoamine transporter (VMAT2) is important in the storage and release of monoamines. Platelet VMAT2 was characterized using high-affinity [(3)H]dihydrotetrabenazine ([(3)H]TBZOH) binding in untreated social phobia (SP) patients (n=20) compared with sex- and age-matched healthy controls (n=15). No significant differences in VMAT2 density (B(max)) and affinity constants (K(d)) were observed.

[Pharmacogenetics: towards personalized medicine].

For 50 years, pharmacogenetics has been studying the genetic basis for variability in drug response between individual patients, both with respect to drug toxicity and drug efficacy. Following the completion of The Human Genome Project about three years ago, and the development of technologies allowing rapid identification of polymorphic alleles using DNA chips, pharmacogenetics would soon allow the introduction of personalized medicine. For most medical disciplines, this would allow pharmacotherapy according to each patient's individual genetic data. This would allow a reduction in the rates of adverse drug reactions, currently responsible by American and European estimates for about 6% of new admissions to internal medicine wards, and causing more morbidity annually than road accidents or breast cancer. The purpose of this review is to delineate the principles of pharmacogenetics, focusing on the aspects closest to implementation in the clinic: the polymorphism of liver CYP450 metabolic enzymes, mostly CYP2D6 and CYP2C19. We shall also review current efforts to better understand the scope of human genome diversity, and present several examples for variability in drug efficacy and genetic polymorphism of drug target genes. Education of health professionals in pharmacogenetics as part of their pharmacology curricula, and explaining its potential to the general public, would be indispensable for the success of personalized medicine.