Evodiamine improves congnitive abilities in SAMP8 and APP(swe)/PS1(ΔE9) transgenic mouse models of Alzheimer's disease

Aim:

To investigate the effect of evodiamine (a quinolone alkaloid from the fruit of Evodia rutaecarpa) on the progression of Alzheimer''s disease in SAMP8 and APP^swe/PS1^ΔE9 transgenic mouse models.

Methods:

The mice at age of 5 months were randomized into the model group, two evodiamine (50 mg·kg⁻¹·d⁻¹ and 100 mg·kg⁻¹·d⁻¹) groups and an Aricept (2 mg·kg⁻¹·d⁻¹) group. The littermates of no-transgenic mice and senescence accelerated mouse/resistance 1 mice (SAMR1) were used as controls. After 4 weeks of treatment, learning abilities and memory were assessed using Morris water-maze test, and glucose uptake by the brain was detected using positron emission tomography/computed tomography (PET/CT). Expression levels of IL-1β, IL-6, and TNF-α in brain tissues were detected using ELISA. Expression of COX-2 protein was determined using Western blot.

Results:

In Morris water-maze test, evodiamine (100 mg·kg⁻¹·d⁻¹) significantly alleviated the impairments of learning ability and memory. Evodiamine (100 mg·kg⁻¹·d⁻¹) also reversed the inhibition of glucose uptake due to development of Alzheimer''s disease traits in mice. Furthermore, the dose of evodiamine significantly decreased the expression of IL-1β, IL-6, TNF-α, and COX-2 that were involved in the inflammation due to Alzheimer''s disease.

Conclusion:

The results indicate that evodiamine (100 mg·kg⁻¹·d⁻¹) improves cognitive abilities in the transgenic models of Alzheimer''s disease.     

Atorvastatin improves insulin sensitivity in mice with obesity induced by monosodium glutamate

Aim:

To examine the mechanisms underlying the effects of atorvastatin on glucose and lipid metabolism.

Methods:

Mice with insulin resistance and obesity induced by monosodium glutamate (MSG) were used. Atorvastatin (80 mg·kg⁻¹·d⁻¹) or vehicle control treatment was given orally once a day for 30 days. Plasma levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and free fatty acids were monitored. Serum insulin and glucose concentrations were used to calculate the insulin resistance index and insulin sensitivity index using a homeostasis model. Body length, waistline circumference, intraperitoneal adipose tissue mass, and total body mass were measured. Semi-quantitative RT-PCR and Western analysis were used to determine the expression of inflammatory factors and proteins involved in inflammation signaling pathways.

Results:

Atorvastatin improved insulin sensitivity, ameliorated glucose tolerance, and decreased plasma levels of total cholesterol, triglycerides, LDL-C, HDL-C and free fatty acids. Semi-quantitative RT-PCR and Western analysis revealed increased expression of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in serum and adipose tissue in MSG obese mice. Atorvastatin treatment decreased expression of IL-6, TNF-α, nuclear factor κB (NF-κB) and I-kappa-B (IκB) kinase-β, but increased the expression of IκB, in adipose tissue.

Conclusion:

Atorvastatin is a potential candidate for the prevention and therapy of diseases associated with insulin resistance such as type 2 diabetes mellitus and cardiovascular disease. One possible mechanism underlying the effects of atorvastatin on glucose and lipid metabolism may be to ameliorate a state of chronic inflammation.     

Double blockade of angiotensin II (AT(1) )-receptors and ACE does not improve weight gain and glucose homeostasis better than single-drug treatments in obese rats

BACKGROUND AND PURPOSE

Combination therapies are becoming increasingly important for the treatment of high blood pressure. Little is known about whether double blockade of angiotensin II (AT₁) receptors and angiotensin-converting enzyme (ACE) exert synergistic metabolic effects.

EXPERIMENTAL APPROACH

Spontaneously hypertensive rats were allowed to choose between palatable chocolate bars and standard chow and were simultaneously treated with the AT₁ blocker telmisartan (8 mg·kg_bw⁻¹·day⁻¹), the ACE inhibitor ramipril (4 mg·kg_bw⁻¹·day⁻¹) or a combination of the two (8 + 4 mg·kg_bw⁻¹·day⁻¹) for 12 weeks.

KEY RESULTS

Although food-dependent energy intake was increased by telmisartan and telmisartan + ramipril compared with ramipril or controls, body weight gain, abundance of fat and plasma leptin levels were decreased. Increased insulin levels in response to an oral glucose tolerance test were comparably attenuated by telmisartan and telmisartan + ramipril, but not by ramipril. During an insulin tolerance test, glucose utilization was equally as effectively improved by telmisartan and telmisartan + ramipril. In response to a stress test, ACTH, corticosterone and glucose increased in controls. These stress reactions were attenuated by telmisartan and telmisartan + ramipril.

CONCLUSIONS AND IMPLICATIONS

The combination of telmisartan + ramipril was no more efficacious in regulating body weight and glucose homeostasis than telmisartan alone. However, telmisartan was more effective than ramipril in improving metabolic parameters and in reducing body weight. The association between the decrease in stress responses and the diminished glucose levels after stress supports our hypothesis that the ability of telmisartan, as an AT₁ receptor blocker, to alleviate stress reactions may contribute to its hypoglycaemic actions.     

Role of α1- and α2-GABA(A) receptors in mediating the respiratory changes associated with benzodiazepine sedation

BACKGROUND AND PURPOSE

The molecular substrates underlying the respiratory changes associated with benzodiazepine sedation are unknown. We examined the effects of different doses of diazepam and alprazolam on resting breathing in wild-type (WT) mice and clarified the contribution of α1- and α2-GABA_A receptors, which mediate the sedative and muscle relaxant action of diazepam, respectively, to these drug effects using point-mutated mice possessing either α1H101R- or α2H101R-GABA_A receptors insensitive to benzodiazepine.

EXPERIMENTAL APPROACH

Room air breathing was monitored using whole-body plethysmography. Different groups of WT mice were injected i.p. with diazepam (1–100 mg·kg⁻¹), alprazolam (0.3, 1 or 3 mg·kg⁻¹) or vehicle. α1H101R and α2H101R mice received 1 or 10 mg·kg⁻¹ diazepam or 0.3 or 3 mg·kg⁻¹ alprazolam. Respiratory frequency, tidal volume, time of expiration and time of inspiration before and 20 min after drug injection were analysed.

KEY RESULTS

Diazepam (10 mg·kg⁻¹) decreased the time of expiration, thereby increasing the resting respiratory frequency, in WT and α2H101R mice, but not in α1H101R mice. The time of inspiration was shortened in WT and α1H101R mice, but not in α2H101R mice. Alprazolam (1–3 mg·kg⁻¹) stimulated the respiratory frequency by shortening expiration and inspiration duration in WT mice. This tachypnoeic effect was partially conserved in α1H101R mice while absent in α2H101R mice.

CONCLUSIONS AND IMPLICATIONS

These results identify a specific role for α1-GABA_A receptors and α2-GABA_A receptors in mediating the shortening by benzodiazepines of the expiratory and inspiratory phase of resting breathing respectively.     

Differential effect of opioid and cannabinoid receptor blockade on heroin-seeking reinstatement and cannabinoid substitution in heroin-abstinent rats

BACKGROUND AND PURPOSE

Opioids and cannabinoids interact in drug addiction and relapse. We investigated the effect of the opioid receptor antagonist naloxone and/or the cannabinoid CB₁ receptor antagonist rimonabant on cannabinoid-induced reinstatement of heroin seeking and on cannabinoid substitution in heroin-abstinent rats.

EXPERIMENTAL APPROACH

Rats were trained to self-administer heroin (30 µg·kg⁻¹ per infusion) under a fixed-ratio 1 reinforcement schedule. After extinction of self-administration (SA) behaviour, we confirmed the effect of naloxone (0.1–1 mg·kg⁻¹) and rimonabant (0.3–3 mg·kg⁻¹) on the reinstatement of heroin seeking induced by priming with the CB₁ receptor agonist WIN55,212-2 (WIN, 0.15–0.3 mg·kg⁻¹). Then, in a parallel set of heroin-trained rats, we evaluated whether WIN (12.5 µg·kg⁻¹ per infusion) SA substituted for heroin SA after different periods of extinction. In groups of rats in which substitution occurred, we studied the effect of both antagonists on cannabinoid intake.

KEY RESULTS

Cannabinoid-induced reinstatement of heroin seeking was significantly attenuated by naloxone (1 mg·kg⁻¹) and rimonabant (3 mg·kg⁻¹) and fully blocked by co-administration of sub-threshold doses of the two antagonists. Moreover, contrary to immediate (1 day) or delayed (90 days) drug substitution, rats readily self-administered WIN when access was given after 7, 14 or 21 days of extinction from heroin, and showed a response rate that was positively correlated with the extinction period. In these animals, cannabinoid intake was increased by naloxone (1 mg·kg⁻¹) and decreased by rimonabant (3 mg·kg⁻¹).

CONCLUSIONS AND IMPLICATIONS

Our findings extend previous research on the crosstalk between cannabinoid and opioid receptors in relapse mechanisms, which suggests a differential role in heroin-seeking reinstatement and cannabinoid substitution in heroin-abstinent rats.

LINKED ARTICLES

This article is part of a themed issue on Cannabinoids in Biology and Medicine. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.163.issue-7     

Improved metabolic status and insulin sensitivity in obese fatty (fa/fa) Zucker rats and Zucker Diabetic Fatty (ZDF) rats treated with the thiazolidinedione,MCC-555

1. We examined the effect of chronic (21 days) oral treatment with the thiazolidinedione, MCC-555 ((±)-5-[{6-(2-fluorbenzyl)-oxy-2-naphy}methyl]-2,4-thiazolidinedione) on metabolic status and insulin sensitivity in obese (fa/fa) Zucker rats and Zucker Diabetic Fatty (ZDF) rats which display an impaired glucose tolerance (IGT) or overt diabetic symptoms, respectively.
2. MCC-555 treatment to obese Zucker rats (10 and 30 mg kg⁻¹) and diabetic ZDF rats (10 mg kg⁻¹) reduced non-esterified fatty acid concentrations in both rat strains and reduced plasma glucose and triglyceride concentrations in the obese Zucker rats. Liver glycogen concentrations were significantly increased by chronic MCC-555 treatment in both obese Zucker rats (30 mg kg⁻¹ day⁻¹) and diabetic ZDF rats (10 mg kg⁻¹ day⁻¹), as compared with vehicle-treated lean and obese rats and there was a significant increase in hepatic glycogen synthase activity in MCC-555-treated diabetic ZDF rats as compared to vehicle-treated controls.
3. During a euglycaemic hyperinsulinaemic clamp, MCC-555-treated obese Zucker rats and diabetic ZDF rats required significantly higher glucose infusion rates to maintain stable glucose concentrations (2.01±0.19 mg min⁻¹ and 6.42±1.03 mg min⁻¹, respectively) than vehicle-treated obese controls (0.71±0.17 mg min⁻¹ and 2.09±0.71 mg min⁻¹; P<0.05), demonstrating improved insulin sensitivity in both Zucker and ZDF rats. MCC-555 treatment also enhanced insulin-induced suppression of hepatic glucose production in ZDF rats as measured using infusions of [6-³H]-glucose under clamp conditions.
4. In conclusion, we have demonstrated that MCC-555 improves metabolic status and insulin sensitivity in obese Zucker and diabetic ZDF rats. MCC-555 may prove a useful compound for alleviating the metabolic disturbances and IGT associated with insulin resistance in man.

     

Rosuvastatin restored adrenergic and nitrergic function in mesenteric arteries from obese rats

BACKGROUND AND PURPOSE

We investigated whether high-fat diet (HFD)-induced obesity was associated with changed function of components of the mesenteric innervation (adrenergic, sensory and nitrergic), the mechanisms involved and the possible effects of rosuvastatin on these changes.

EXPERIMENTAL APPROACH

Male Wistar rats were divided into three groups. (i) rats fed a standard diet (control group); (ii) rats fed a HFD (33.5% fat) for 7 weeks; and (iii) rats fed a HFD and treated with rosuvastatin (15 mg·kg⁻¹·day⁻¹) for 7 weeks. Segments of isolated mesenteric arteries were exposed to electric field stimulation (EFS) with or without tetrodotoxin, phentolamine, 7-nitroindazole (7NI) or N^ω nitro-L-arginine methyl ester (L-NAME). Noradrenaline, ATP and NO release, and nNOS expression were also measured.

KEY RESULTS

EFS induced a greater frequency-dependent contraction in obese than in control rats. In HFD rats, phentolamine reduced contractions elicited by EFS, but noradrenaline release was greater and ATP release decreased. L-NAME and 7NI increased contractions to EFS in segments from control rats, but not in those from HFD rats. NO release and nNOS expression were lower in arterial segments from HFD rats than in control rats. All these changes in HFD rats were reversed by treatment with rosuvastatin.

CONCLUSIONS AND IMPLICATIONS

Neural control of mesenteric vasomotor tone was altered in HFD rats. Enhanced adrenergic and diminished nitrergic components both contributed to increased vasoconstrictor responses to EFS. All these changes were reversed by rosuvastatin, indicating novel mechanisms of statins in neural regulation of vascular tone.     

Reduced signal transduction by 5-HT4 receptors after long-term venlafaxine treatment in rats

BACKGROUND AND PURPOSE

The 5-HT₄ receptor may be a target for antidepressant drugs. Here we have examined the effects of the dual antidepressant, venlafaxine, on 5-HT₄ receptor-mediated signalling events.

EXPERIMENTAL APPROACH

The effects of 21 days treatment (p.o.) with high (40 mg·kg⁻¹) and low (10 mg·kg⁻¹) doses of venlafaxine, were evaluated at different levels of 5-HT₄ receptor-mediated neurotransmission by using in situ hybridization, receptor autoradiography, adenylate cyclase assays and electrophysiological recordings in rat brain. The selective noradrenaline reuptake inhibitor, reboxetine (10 mg·kg⁻¹, 21 days) was also evaluated on 5-HT₄ receptor density.

KEY RESULTS

Treatment with a high dose (40 mg·kg⁻¹) of venlafaxine did not alter 5-HT₄ mRNA expression, but decreased the density of 5-HT₄ receptors in caudate-putamen (% reduction = 26 ± 6), hippocampus (% reduction = 39 ± 7 and 39 ± 8 for CA1 and CA3 respectively) and substantia nigra (% reduction = 49 ± 5). Zacopride-stimulated adenylate cyclase activation was unaltered following low-dose treatment (10 mg·kg⁻¹) while it was attenuated in rats treated with 40 mg·kg⁻¹ of venlafaxine (% reduction = 51 ± 2). Furthermore, the amplitude of population spike in pyramidal cells of CA1 of hippocampus induced by zacopride was significantly attenuated in rats receiving either dose of venlafaxine. Chronic reboxetine did not modify 5-HT₄ receptor density.

CONCLUSIONS AND IMPLICATIONS

Our data indicate a functional desensitization of 5-HT₄ receptors after chronic venlafaxine, similar to that observed after treatment with the classical selective inhibitors of 5-HT reuptake.     

AVE8134, a novel potent PPARα agonist, improves lipid profile and glucose metabolism in dyslipidemic mice and type 2 diabetic rats

Aim:

AVE8134 is a structurally novel potent PPARα agonist. The aim of this study is to investigate the efficacy of AVE8134 on lipid profile and glucose metabolism in dyslipidemic mice and type 2 diabetic rats.

Methods:

A cell based PPAR Gal4 transactivation assay was constructed for testing the activities of AVE8134 at 3 different PPAR isoforms in vitro. Transgenic human Apo A1 (hApo A1) mice and insulin-resistant ZDF rats were used to evaluate the effects of AVE8134 in vivo.

Results:

AVE8134 was a full PPARα dominated PPAR agonist (the values of EC₅₀ for human and rodent PPARα receptor were 0.01 and 0.3 μmol/L, respectively). AVE8134 was not active at PPARδ receptor. In female hApo A1 mice, AVE8134 (1–30 mg·kg⁻¹·d⁻¹, po for 12 d) dose-dependently lowered the plasma triglycerides, and increased the serum HDL-cholesterol, hApo A1 and mouse Apo E levels. In female ZDF rats, AVE8134 (3–30 mg·kg⁻¹·d⁻¹ for 2 weeks) improved insulin-sensitivity index. In pre-diabetic male ZDF rats (at the age of 7 weeks), AVE8134 (10 mg·kg⁻¹·d⁻¹ for 8 weeks) produced an anti-diabetic action comparable to rosiglitazone, without the PPARγ mediated adverse effects on body weight and heart weight. In male ZDF rats (at the age of 6 weeks), AVE8134 (20 mg·kg⁻¹·d⁻¹ for 12 weeks) increased mRNA levels of the target genes LPL and PDK4 about 20 fold in the liver, and there was no relevant effect with rosiglitazone.

Conclusion:

AVE8134 improves lipid profile and glucose metabolism in dyslipidemic mice and type 2 diabetic rats.     

Mechanisms mediating the ability of caffeine to influence MDMA (��Ecstasy��)-induced hyperthermia in rats

Background and purpose:

Caffeine exacerbates the hyperthermia associated with an acute exposure to 3,4 methylenedioxymethamphetamine (MDMA, ‘Ecstasy’) in rats. The present study investigated the mechanisms mediating this interaction.

Experimental approach:

Adult male Sprague-Dawley rats were treated with caffeine (10 mg·kg⁻¹; i.p.) and MDMA (15 mg·kg⁻¹; i.p.) alone and in combination. Core body temperatures were monitored before and after drug administration.

Key results:

Central catecholamine depletion blocked MDMA-induced hyperthermia and its exacerbation by caffeine. Caffeine provoked a hyperthermic response when the catecholamine releaser d-amphetamine (1 mg·kg⁻¹) was combined with the 5-HT releaser d-fenfluramine (5 mg·kg⁻¹) or the non-selective dopamine receptor agonist apomorphine (1 mg·kg⁻¹) was combined with the 5-HT₂ receptor agonist DOI (2 mg·kg⁻¹) but not following either agents alone. Pretreatment with the dopamine D₁ receptor antagonist Schering (SCH) 23390 (1 mg·kg⁻¹), the 5-HT₂ receptor antagonist ketanserin (5 mg·kg⁻¹) or α₁-adreno- receptor antagonist prazosin (0.2 mg·kg⁻¹) blocked MDMA-induced hyperthermia and its exacerbation by caffeine. Co-administration of a combination of MDMA with the PDE-4 inhibitor rolipram (0.025 mg·kg⁻¹) and the adenosine A_1/2 receptor antagonist 9-chloro-2-(2-furanyl)-[1,2,4]triazolo[1,5-C]quinazolin-5-amine 15943 (10 mg·kg⁻¹) or the A_2A receptor antagonist SCH 58261 (2 mg·kg⁻¹) but not the A₁ receptor antagonist DPCPX (10 mg·kg⁻¹) exacerbated MDMA-induced hyperthermia.

Conclusions and implications:

A mechanism comprising 5-HT and catecholamines is proposed to mediate MDMA-induced hyperthermia. A combination of adenosine A_2A receptor antagonism and PDE inhibition can account for the exacerbation of MDMA-induced hyperthermia by caffeine.     

17β-Estradiol inhibition of PPARγ-induced adipogenesis and adipocyte-specific gene expression

Aim:

To investigate the molecular interaction of peroxisome proliferator-activated receptor γ (PPARγ) with 17β-estradiol (E) in the regulation of adipogenesis.

Methods:

Female ovariectomized (OVX) mice and differentiated 3T3-L1 adipocytes were treated with combinations of the PPARγ agonist troglitazone or E, and the variables and determinants of adipogenesis were measured using in vivo and in vitro approaches.

Results:

Troglitazone (250 mg·kg⁻¹·d⁻¹ for 13 weeks) decreased the size of adipocytes without the change in white adipose tissue (WAT) mass and increased the expression of adipocyte-specific genes, such as PPARγ, adipocyte fatty acid binding protein, and lipoprotein lipase, compared with OVX control mice. E (0.05 mg/pellet, sc implanted) significantly reduced WAT mass, adipocyte size, and adipose marker gene expression. When mice were concomitantly treated with troglitazone and E, E blunted the effects of troglitazone on WAT mass, adipocyte size, and adipose PPARγ target gene expression. Consistent with the in vivo data, E (10 μmol/L) treatment inhibited lipid accumulation and the expression of adipocyte-specific genes caused by troglitazone (10 μmol/L) in 3T3-L1 cells. E (10 μmol/L) also decreased troglitazone-induced PPARγ reporter activity through both estrogen receptor (ER) α and ERβ. Mechanistic studies indicated that E (0.1 μmol/L) decreased the DNA binding of PPARγ induced by troglitazone (1 μmol/L) and inhibited the recruitment of the PPARγ coactivator CREB-binding protein.

Conclusion:

These results suggest that in vivo and in vitro treatment of E interferes with the actions of PPARγ on adipogenesis by down-regulating adipogenesis-related genes, which are mediated through the inhibition of PPARγ coactivator recruitment. In addition, it is likely that the activities of PPARγ activators may be enhanced in estrogen-deficient states.     

Loss of multidrug and toxin extrusion 1 (MATE1) is associated with metformin-induced lactic acidosis

BACKGROUNDS AND PURPOSE

Lactic acidosis is a fatal adverse effect of metformin, but the risk factor remains unclear. Multidrug and toxin extrusion 1 (MATE1) is expressed in the luminal membrane of the kidney and liver. MATE1 was revealed to be responsible for the tubular and biliary secretion of metformin. Therefore, some MATE polymorphisms, that cause it to function abnormally, are hypothesized to induce lactic acidosis. The purpose of this study is to clarify the association between MATE dysfunction and metformin-induced lactic acidosis.

EXPERIMENTAL APPROACH

Blood lactate, pH and bicarbonate ion (HCO₃^-) levels were evaluated during continuous administration of 3 mg·mL⁻¹ metformin in drinking water using Mate1 knockout (−/−), heterozygous (+/−) and wild-type (+/+) mice. To determine the tissue accumulation of metformin, mice were given 400 mg·kg⁻¹ metformin orally. Furthermore, blood lactate data were obtained from diabetic patients given metformin.

KEY RESULTS

Seven days after metformin administration in drinking water, significantly higher blood lactate, lower pH and HCO₃^- levels were observed in Mate1^−/− mice, but not in Mate1^+/− mice. The blood lactate levels were not affected in patients with the heterozygous MATE variant (MATE1-L125F, MATE1-G64D, MATE2-K-G211V). Sixty minutes after metformin administration (400 mg·kg⁻¹, p.o.) the hepatic concentration of metformin was markedly higher in Mate1^−/− mice than in Mate1^+/+ mice.

CONCLUSION AND IMPLICATIONS

MATE1 dysfunction caused a marked elevation in the metformin concentration in the liver and led to lactic acidosis, suggesting that the homozygous MATE1 variant could be one of the risk factors for metformin-induced lactic acidosis.     

The α7 nicotinic ACh receptor agonist compound B and positive allosteric modulator PNU-120596 both alleviate inflammatory hyperalgesia and cytokine release in the rat

BACKGROUND AND PURPOSE

Agonists selective for the α7 nicotinic acetylcholine (nACh) receptor produce anti-hyperalgesic effects in rodent models of inflammatory pain, via direct actions on spinal pain circuits and possibly via attenuated release of peripheral pro-inflammatory mediators. Increasingly, allosteric modulation of ligand-gated receptors is recognized as a potential strategy to obtain desired efficacy in the absence of the putative adverse effects associated with agonist activation.

EXPERIMENTAL APPROACH

We compared the anti-hyperalgesic and anti-inflammatory effects of the α7 nACh receptor agonist compound B with the positive allosteric modulator (PAM) PNU-120596 and the standard non-steroidal anti-inflammatory drug (NSAID), diclofenac, in rats with hind paw inflammation induced by either formalin, carrageenan or complete Freund''s adjuvant (CFA).

KEY RESULTS

When administered before carrageenan, both diclofenac (30 mg·kg⁻¹) and PNU-120596 (30 mg·kg⁻¹) significantly reduced mechanical hyperalgesia and weight-bearing deficits for up to 4 h. Compound B (30 mg·kg⁻¹) also attenuated both measures of pain-like behaviour, albeit less robustly. Whereas compound B and PNU-120596 attenuated the carrageenan-induced increase in levels of TNF-α and IL-6 within the hind paw oedema, diclofenac only attenuated IL-6 levels. Established mechanical hyperalgesia induced by carrageenan or CFA was also partially reversed by compound B and PNU-120596. However, diclofenac was considerably more efficacious. Formalin-induced nocifensive behaviours were only reversed by compound B, albeit at doses which disrupted motor performance.

CONCLUSIONS AND IMPLICATIONS

α7 nACh receptor PAMs could prove to be useful in the treatment of inflammatory pain conditions, which respond poorly to NSAIDs or in situations where NSAIDs are contra-indicated.     

Preclinical characterization of WAY-211612: a dual 5-HT uptake inhibitor and 5-HT1A receptor antagonist and potential novel antidepressant

Background and purpose

As a combination of 5-HT selective reuptake inhibitor (SSRI) with 5-HT_1A receptor antagonism may yield a rapidly acting antidepressant, WAY-211612, a compound with both SSRI and 5-HT_1A receptor antagonist activities, was evaluated in preclinical models.

Experimental approach

Occupancy studies confirmed the mechanism of action of WAY-211612, while its in vivo profile was characterized in microdialysis and behavioural models.

Key results

WAY-211612 inhibited 5-HT reuptake (K_i = 1.5 nmol·L⁻¹; K_B = 17.7 nmol·L⁻¹) and exhibited full 5-HT_1A receptor antagonist activity (K_i = 1.2 nmol·L⁻¹; K_B = 6.3 nmol·L⁻¹; I_max 100% in adenyl cyclase assays; K_B = 19.8 nmol·L⁻¹; I_max 100% in GTPγS). WAY-211612 (3 and 30 mg·kg⁻¹, po) occupied 5-HT reuptake sites in rat prefrontal cortex (56.6% and 73.6% respectively) and hippocampus (52.2% and 78.5%), and 5-HT_1A receptors in the prefrontal cortex (6.7% and 44.7%), hippocampus (8.3% and 48.6%) and dorsal raphe (15% and 83%). Acute or chronic treatment with WAY-211612 (3–30 mg·kg⁻¹, po) raised levels of cortical 5-HT approximately twofold, as also observed with a combination of an SSRI (fluoxetine; 30 mg·kg⁻¹, s.c.) and a 5-HT_1A antagonist (WAY-100635; 0.3 mg·kg⁻¹, s.c). WAY-211612 (3.3–30 mg·kg⁻¹, s.c.) decreased aggressive behaviour in the resident-intruder model, while increasing the number of punished crossings (3–30 mg·kg⁻¹, i.p. and 10–56 mg·kg⁻¹, po) in the mouse four-plate model and decreased adjunctive drinking behaviour (56 mg·kg⁻¹, i.p.) in the rat scheduled-induced polydipsia model.

Conclusions and implications

These findings suggest that WAY-211612 may represent a novel antidepressant.     

Zonisamide,an antiepileptic drug,alleviates diabetic cardiomyopathy by inhibiting endoplasmic reticulum stress

Endoplasmic reticulum stress(ER stress)plays a key role in the development of cardiac hypertrophy and diabetic cardiomyopathy(DCM).Zonisamide(ZNS)was originally developed as an antiepileptic drug.Studies have shown that ZNS suppresses ER stress-induced neuronal cell damage in the experimental models of Parkinson’s disease.Herein,we investigated whether ZNS improved DCM by attenuating ER stress-induced apoptosis.C57BL/6J mice were fed with high-fat diet(HFD)and intraperitoneally injected with low-dose streptozotocin(STZ)to induce type 2 diabetes mellitus(T2DM),and then treated with ZNS(40 mg·kg^?1·d^?1,i.g.)for 16 weeks.We showed that ZNS administration slightly ameliorated the blood glucose levels,but significantly alleviated diabetes-induced cardiac dysfunction and hypertrophy.Furthermore,ZNS administration significantly inhibited the Bax and caspase-3 activity,upregulated Bcl-2 activity,and decreased the proportion of TUNEL-positive cells in heart tissues.We analyzed the hallmarks of ER stress in heart tissues,and revealed that ZNS administration significantly decreased the protein levels of GRP78,XBP-1s,ATF6,PERK,ATF4,and CHOP,and elevated Hrd1 protein.In high glucose(HG)-treated primary cardiomyocytes,application of ZNS(3μM)significantly alleviated HG-induced cardiomyocyte hypertrophy and apoptosis.ZNS application also suppressed activated ER stress in HG-treated cardiomyocytes.Moreover,preapplication of the specific ER stress inducer tunicamycin(10 ng/mL)eliminated the protective effects of ZNS against HG-induced cardiac hypertrophy and ER stress-mediated apoptosis.Our findings suggest that ZNS improves the cardiac diastolic function in diabetic mice and prevents T2DM-induced cardiac hypertrophy by attenuating ER stress-mediated apoptosis.     

Pharmacokinetics of panaxatrol disuccinate sodium, a novel anti-cancer drug from Panax notoginseng, in healthy volunteers and patients with advanced solid tumors

Aim:

To evaluate single-dose and multiple-dose pharmacokinetics of panaxatrol disuccinate sodium in healthy volunteers and patients with advanced solid tumors.

Methods:

In the single-dose pharmacokinetic study, 27 healthy volunteers received panaxatrol disuccinate sodium in three doses (70, 100, and 140 mg·m⁻²). In the multiple-dose pharmacokinetic study, Panaxatrol disuccinate sodium was administered to 8 patients at 100 mg·m⁻² daily in a 30-day continuous intravenous injection. Determination of the panaxatrol disuccinate sodium plasma concentration was performed by an LC-MS method. The pharmacokinetic analysis system — Drug and Statistics (DAS) — was applied to assess plasma panaxatrol disuccinate sodium concentration-time data.

Results:

After a single intravenous dose of 70, 100, or 140 mg·m⁻² was administered to subjects, panaxatrol disuccinate sodium distributed broadly, and the plasma concentration of panaxatrol disuccinate sodium declined rapidly. No significant differences were observed in the main pharmacokinetic parameters among the three dosing groups, including AUC_0–t, MRT_0–t, VRT_0–t, t_1/2Z, CL_z/F, V_z/F, and C₀ (P>0.05). In the multiple-dose pharmacokinetic study, the mean steady-state peak concentration (C_max), trough concentration (C_min), average concentration (C_av), mean steady state AUC (AUC_ss) and the degree of fluctuation were 13.96±15.48 mg·L⁻¹, 0.18±0.29 mg·L⁻¹, 0.15±0.29 mg·L⁻¹, 3.58±6.94 mg·L⁻¹·h, and 148.00±117.18, respectively. At any given dose of panaxatrol disuccinate sodium, interindividual variability in the pharmacokinetic parameters was obvious.

Conclusion:

The effect of the dose level on single-dose pharmacokinetics of panaxatrol disuccinate sodium was not significant. No accumulation was observed with exposure to 100 mg·m⁻² panaxatrol disuccinate sodium in the 30-day continuous intravenous injection. All subjects were evaluated for tolerability throughout the study. Thus, the phase II dose of panaxatrol disuccinate sodium may be considered to be 100 mg·m⁻² for a 30-day continuous intravenous injection to treat patients with advanced solid tumors.     

Investigation of Debio 025, a cyclophilin inhibitor, in the dystrophic mdx mouse, a model for Duchenne muscular dystrophy

Background and purpose:

Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder caused by the absence of the cytoskeletal protein dystrophin. This leads to muscle cell death accompanied by chronic inflammation. Cyclosporin A (CsA) is a powerful immunosuppressive drug, which has been proposed for DMD treatment. CsA also directly regulates the mitochondrial permeability transition pore (mPTP), which participates in cell death pathways through the inhibition of cyclophilin D. Here, we evaluated whether Debio 025, a cyclophilin inhibitor with no immunosuppressive activity, improves the dystrophic condition in a mouse model of DMD, through regulation of mPTP.

Experimental approach:

The potency of Debio 025 to protect mouse dystrophic cells against mitochondria-mediated death was assessed by caspase-3 activity and calcium retention capacity assays. Mdx^5Cv mice (3-week-old) were treated daily by gavage for 2 weeks with Debio 025 (10, 30 or 100 mg kg⁻¹), CsA (10 mg kg⁻¹) or placebo. The effects on muscle necrosis and function were measured.

Key results:

In vitro investigations showed protective effect of low concentrations of Debio 025 against cell death. Histology demonstrated that Debio 025 partially protected the diaphragm and soleus muscles against necrosis (10 and 100 mg kg⁻¹, respectively). Hindlimb muscles from mice receiving Debio 025 at 10 mg kg⁻¹ relaxed faster, showed alteration in the stimulation frequency-dependent recruitment of muscle fibres and displayed a higher resistance to mechanical stress.

Conclusions and implications:

Debio 025 partially improved the structure and the function of the dystrophic mouse muscle, suggesting that therapies targeting the mPTP may be helpful to DMD patients.     

Pyrazolone derivative C29 protects against HFD-induced obesity in mice via activation of AMPK in adipose tissue

Beige adipocytes have been considered as a potential strategy in anti-obesity therapy because of its thermogenic capacity. AMP-activated protein kinase (AMPK) plays important roles in regulating adipose tissue function. C29 is a novel pyrazolone derivative with AMPK activity. In the current study, we investigated the role of C29 in the regulation of thermogenesis using differentiated adipocytes and diet-induced obese mice, and explored the mechanisms that might be involved in energy expenditure via adipocyte AMPK activation. We showed that treatment with C29 (2.5–10 μM) concentration-dependently increased thermogenesis in differentiated preadipocytes separated from inguinal white adipose tissue (iWAT), evidenced by increased expression levels of thermogenesis markers such as Ucp1, Pgc-1α, Dio2, Prdm16, Cox7a1, Cox8b, Elovl3, and Cidea, fatty acid oxidation (FAO) genes including Cpt1a, Lcad and Pparα, as well as beige-selective genes such as Cd137, Tmem26, Slc27a1, and Tbx1. In high-fat diet (HFD)-fed mice, oral administration of C29 (30 mg·kg⁻¹·day⁻¹) for 9 weeks alleviated HFD-induced obesity, promoted energy expenditure and modulated iWAT browning. However, these effects were not observed in adipose-specific AMPKα1/α2 knockout (AKO) mice following C29 administration. Together, this study demonstrates that C29 regulates energy balance via adipocyte AMPK. Our findings show that the discovery of AMPK activators that specifically target adipose tissue may have therapeutic potential for treating obesity-related metabolic diseases.     

Pharmacologically inhibiting phosphoglycerate kinase 1 for glioma with NG52

Inhibition of glycolysis process has been an attractive approach for cancer treatment due to the evidence that tumor cells are more dependent on glycolysis rather than oxidative phosphorylation pathway.Preliminary evidence shows that inhibition of phosphoglycerate kinase 1(PGK1)kinase activity would reverse the Warburg effect and make tumor cells lose the metabolic advantage for fueling the proliferation through restoration of the pyruvate dehydrogenase(PDH)activity and subsequently promotion of pyruvic acid to enter the Krebs cycle in glioma.However,due to the lack of small molecule inhibitors of PGK1 kinase activity to treat glioma,whether PGK1 could be a therapeutic target of glioma has not been pharmacologically verified yet.In this study we developed a high-throughput screening and discovered that NG52,previously known as a yeast cell cycle-regulating kinase inhibitor,could inhibit the kinase activity of PGK1(the IC50=2.5±0.2μM).We showed that NG52 dose-dependently inhibited the proliferation of glioma U87 and U251 cell lines with IC50 values of 7.8±1.1 and 5.2±0.2μM,respectively,meanwhile it potently inhibited the proliferation of primary glioma cells.We further revealed that NG52(12.5–50μM)effectively inhibited the phosphorylation of PDHK1 at Thr338 site and the phosphorylation of PDH at Ser293 site in U87 and U251 cells,resulting in more pyruvic acid entering the Krebs cycle with increased production of ATP and ROS.Therefore,NG52 could reverse the Warburg effect by inhibiting PGK1 kinase activity,and switched cellular glucose metabolism from anaerobic mode to aerobic mode.In nude mice bearing patient-derived glioma xenograft,oral administration of NG52(50,100,150 mg·kg?1·d?1,for 13 days)dose-dependently suppressed the growth of glioma xenograft.Together,our results demonstrate that targeting PGK1 kinase activity might be a potential strategy for glioma treatment.