Cardiovascular and sedation reversal effects of intramuscular administration of atipamezole in dogs treated with medetomidine hydrochloride with or without the peripheral α2-adrenoceptor antagonist vatinoxan hydrochloride.

OBJECTIVE: To investigate the cardiovascular and sedation reversal effects of IM administration of atipamezole (AA) in dogs treated with medetomidine hydrochloride (MED) or MED and vatinoxan (MK-467). ANIMALS: 8 purpose-bred, 2-year-old Beagles. PROCEDURES: A randomized, blinded, crossover study was performed in which each dog received 2 IM treatments at a ≥ 2-week interval as follows: injection of MED (20 µg/kg) or MED mixed with 400 µg of vatinoxan/kg (MEDVAT) 30 minutes before AA (100 µg/kg). Sedation score, heart rate, mean arterial and central venous blood pressures, and cardiac output were recorded before and at various time points (up to 90 minutes) after AA. Cardiac and systemic vascular resistance indices were calculated. Venous blood samples were collected at intervals until 210 minutes after AA for drug concentration analysis. RESULTS: Heart rate following MED administration was lower, compared with findings after MEDVAT administration, prior to and at ≥ 10 minutes after AA. Mean arterial blood pressure was lower with MEDVAT than with MED at 5 minutes after AA, when its nadir was detected. Overall, cardiac index was higher and systemic vascular resistance index lower, indicating better cardiovascular function, in MEDVAT-atipamezole-treated dogs. Plasma dexmedetomidine concentrations were lower and recoveries from sedation were faster and more complete after MEDVAT treatment with AA than after MED treatment with AA. CONCLUSIONS AND CLINICAL RELEVANCE: Atipamezole failed to restore heart rate and cardiac index in medetomidine-sedated dogs, and relapses into sedation were observed. Coadministration of vatinoxan with MED helped to maintain hemodynamic function and hastened the recovery from sedation after AA in dogs.

Sedative effect of intramuscular medetomidine with and without vatinoxan (MK-467), and its reversal with atipamezole in sheep.

OBJECTIVE: To evaluate the effect of the peripherally acting α2-adrenoceptor antagonist vatinoxan (MK-467) on the sedative properties of medetomidine (MED) when injected intramuscularly (IM) in the same syringe and on reversal of this sedation with atipamezole in sheep. STUDY DESIGN: Randomized, blinded, crossover experimental trial. ANIMALS: Eight healthy adult female sheep. METHODS: Sheep received MED (30 µg kg-1 IM) alone or combined in the same syringe with vatinoxan (300 µg kg-1 IM, MED+VAT) with a 2 week washout period. Atipamezole (150 µg kg-1 IM) was administered 30 minutes later for reversal. Sedation was assessed using two sedation scores, a visual analog score and a descriptive scale before treatments (T0) and at intervals up to 5 hours thereafter. Pulse rate (PR) was counted at T0 and at 30 (T30) and 90 (T90) minutes. Rectal temperature was measured at T0 and T90 postinjection. Plasma samples were analyzed for drug concentrations at T30 and T90. RESULTS: The first signs of sedation were seen significantly earlier after MED+VAT (4.6 ± 1.7 minutes versus 9.4 ± 2.6 minutes after MED) and the sedation scores were significantly higher after MED+VAT than MED. All animals laid with head down 10.0 ± 3.4 minutes after MED+VAT, whereas three MED animals did not become recumbent before atipamezole was administered. The plasma concentrations of dexmedetomidine were significantly higher at T30 (2.47 ± 0.2 ng mL-1) and significantly lower at T90 (1.23 ± 0.3 ng mL-1) with MED+VAT than with MED (1.19 ± 0.8 and 1.83 ± 0.4 ng mL-1, respectively). While no significant differences were observed between treatments in PR at T30, PR at T90 was significantly higher with MED+VAT than with MED. CONCLUSIONS AND CLINICAL RELEVANCE: When administered IM in the same syringe, vatinoxan hastened and intensified the initial sedative effects of MED and enhanced the sedation reversal by atipamezole.

A reactive oxygen species activation mechanism contributes to Sophoridine-induced apoptosis in rat liver BRL-3A cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Sophora alopecuroides L., a traditional Chinese herb, has been widely used to treat numerous diseases throughout China. Quinolizidine alkaloids were identified as active components in Sophora alopecuroides L., and Sophoridine (SRI) is the major component in the Quinolizidine alkaloids. AIM OF THE STUDY: To investigate the toxic effects of SRI in rat liver BRL-3A cells and to explore potential ROS-related mechanisms. MATERIALS AND METHODS: Cell viability, cytotoxicity, apoptosis, intracellular generation of ROS, GSH/GSSG ratio and levels of proteins in mitochondria apoptosis pathway were analyzed. RESULTS: Our data indicated that SRI could suppress BRL-3A cells viability in a concentration- and time-dependent manner and increase cytotoxicity, ROS accumulation and cell apoptosis in a concentration-dependent manner. Expressions and activities of apoptotic related proteins were upregulated, whereas expression of Bcl-2 was downregulated after treatment. Furthermore, level of H2O2 was increased, whereas level of Superoxide was not changed after treatment. Moreover, the antioxidant N-acetylcysteine reversed SRI-induced apoptosis and ROS accumulation. CONCLUSION: Our data suggest that SRI promotes rat liver BRL-3A cells apoptosis by increasing intracellular ROS accumulation.

The synergy of diammonium glycyrrhizinate remarkably reduces the toxicity of oxymatrine in ICR mice.

Most traditional Chinese medicine prescription dosages are imprecise. This study analyzes the toxicities and adverse effects of a combination the active ingredients of licorice and Kushen medicine: oxymatrine (OMT) and diammonium glycyrrhizinate (DG). The median lethal dose (LD50) and mortality were analyzed in single-dose OMT (or DG) intraperitoneally injected mice with or without combination DG (or OMT). Body weight changes as well as levels of serum sodium and potassium, alanine transaminase (ALT), aspartate transaminase (AST), creatinine, and urea were measured in mice treated with a daily dose of OMT and/or DG for 14days. This study showed that the LD50 of OMT for males and females were 347.44 and 429.15mg/kg, respectively. The LD50 of DG were 525.10 and 997.26mg/kg for males and females, respectively. DG significantly decreased the mice LD50-induced mortality of the OMT, however OMT did not succeed in reducing the LD50-induced mortality rate of DG. The combination of OMT and DG obviously attenuated the changes of the body weight, serum sodium, and potassium induced by DG or OMT alone. These results suggested that toxicity and adverse effects of the OMT was significantly attenuated by DG. The OMT neutralized the adverse effects of the DG, but not the toxicity.

Matrine suppresses proliferation and induces apoptosis in human cholangiocarcinoma cells through suppression of JAK2/STAT3 signaling.

BACKGROUND: Constitutive activation of signal transducer and activator of transcription 3 (STAT3) signaling contributes to apoptosis resistance in cholangiocarcinoma. The aim of this study is to check whether matrine, an alkaloid isolated from traditional Chinese herb Sophora flavescens ait, can exert cytotoxic effects against cholangiocarcinoma cells via inactivation of STAT3 signaling. METHODS: Mz-ChA-1 and KMCH-1 cholangiocarcinoma cells were treated with matrine at 0.25-2.0 g/L for 48 h and cell viability and apoptosis were assessed. Apoptosis-related molecular changes and STAT3 phosphorylation and transcriptional activities were measured after matrine treatment for 48 h. The effect of expression of a constitutively active STAT3 mutant on matrine-induced apoptosis was determined. RESULTS: Matrine significantly inhibited the viability and induced apoptosis in cholangiocarcinoma cells. Matrine treatment caused loss of mitochondrial membrane potential, release of mitochondrial cytochrome c, and activation of caspase-9 and -3. Matrine-induced apoptosis was inhibited in the presence of the caspase-3 inhibitor Ac-DEVD-CHO. Matrine reduced the phosphorylation levels of Janus kinase 2 (JAK2) and STAT3, inhibited STAT3-dependent transcriptional activity, and downregulated STAT3 target gene Mcl-1. Notably, expression of the constitutively active form of STAT3 significantly antagonized matrine-induced apoptosis of cholangiocarcinoma cells. CONCLUSION: Matrine can trigger mitochondrial apoptotic death of cholangiocarcinoma cells largely through inhibition of JAK2/STAT3 signaling. Therefore, matrine represents a potentially effective anticancer agent for cholangiocarcinoma.

Are 5-HT receptors or beta-adrenoceptors involved in idazoxan-induced food and water intake?

Idazoxan (10 mg/kg, i.p.) produces an unexpected increase in food intake in freely-feeding rats which has been linked to its high affinity for non-adrenoceptor idazoxan binding sites. In this study, a dose-related antagonism of idazoxan-induced food intake by the beta-adrenoceptor antagonist (-)-propranolol (5-20 mg/kg, i.p.), which also blocks 5-HT1 (5-hydroxytryptamine1) receptors has been demonstrated. (+)-Propranolol (10, 20 mg/kg, i.p.) did not attenuate idazoxan-induced feeding. (-)-Propranolol (10 mg/kg, i.p.) but not the (+)-enantiomer (10 mg/kg, i.p.) also significantly inhibited the food intake, induced by the 5-HT1A agonist 8-OH-DPAT (0.25 mg/kg, i.p.). Idazoxan-induced feeding was not altered by the selective beta-adrenoceptor antagonists betaxolol (beta 1; 5 mg/kg, i.p.) and ICI 118,551 (beta 2; 5 mg/kg, i.p.) but was potentiated by the 5-HT receptor antagonist metergoline (5 mg/kg, i.p.). The anomalous findings with metergoline may reflect its action at different sub-types of 5-HT receptor. The water intake induced by idazoxan and the peripherally-active alpha 2-adrenoceptor antagonist L-659,066 was also blocked in a stereoselective manner by propranolol (10 mg/kg) but not significantly by either metergoline (5 mg/kg, i.p.), the beta 1-adrenoceptor antagonist betaxolol (5 mg/kg, i.p.) nor by the beta 2-adrenoceptor antagonist ICI 118,551 (5 mg/kg, i.p.). These results suggest that the food intake induced by idazoxan (and perhaps mediated by non-adrenoceptor idazoxan binding sites) may involve the 5-HT system, although further studies, using antagonists acting selectively at the different sub-types of 5-HT receptor, are required to confirm this.(ABSTRACT TRUNCATED AT 250 WORDS)

Quaternary acetate and propionate esters of 3-hydroxyquinolizidine.

The preparation of the quaternary acetate and propionate esters of 3-hydroxyquinolizidine is described. Tentative structures are assigned on the basis of NMR data. Results of preliminary pharmacological screening of the methiodide and hydrochloride salts are given.

A critical study on RO-4-1284 antagonism in mice.

Ro-4-1284 is found to produce ptosis, hypothermia, sedation and miosis in mice, and the antagonsim to these symptoms is investigated. The study reports the differential effects of various pharmacologically distinct classes of compounds. The relevance of this type of experiments to possible antidepressant drug activity is discussed.