Distribution,Metabolism and Tumoricidal Activity of Doxorubicin Administered in Sorbitan Monostearate (Span 60) Niosomes in the Mouse

Purpose. Encapsulation of doxorubicin in niosomes was sought as a route to tumour targeting and improved tumoricidal through the alteration of doxorubicin pharmacokinetics and metabolism. Methods. Doxorubicin niosomes (10 mg kg^–l doxorubicin) prepared from sorbitan monostearate (Span 60), cholesterol and choleth-24 (a 24 oxyethylene cholesteryl ether) in the molar ratio 45:45:10 were administered intravenously to female NMRI mice bearing the MAC 15A subcutaneously implanted tumour. Plasma doxorubicin was fractionated by gel filtration and quantified by HPLC with fluorometric detection as niosome-associated doxorubicin and released doxorubicin. Tumoricidal activity of the formulation was assessed by the intravenous injection of 5 mg kg^–1 and 10 mg kg^–1 doxorubicin niosomes to male NMRI mice bearing a 6 day old MAC 15A tumour. Results. At least 90% of the plasma doxorubicin was associated with the niosome fraction 4 h after dosing, and 50% was still associated after 24 h. The clearance of doxorubicin released from the niosomes was about 10 fold greater than the clearance of niosomal doxorubicin (176.5 mL h^–l and 16.2 mL h^–1, respectively). The area under the plasma level-time curve increased 6 fold when doxorubicin was administered in niosomes, compared to doxorubicin solution (66.0 µg.h mL^–l and 10.3 µg.h mL^–1, respectively). The area under the tumour level time curve was increased by over 50% by the administration of doxorubicin in niosomes when compared to the drug administered in solution (58.6 µg.h mL^–l and 34.3 µg.h mL^–1, respectively). There was no statistically significant difference between levels of the drug in the heart when niosomal doxorubicin or doxorubicin solution were administered. Doxorubicin metabolites, namely doxorubicinol and the aglycones doxorubicinone, doxorubicinolone and 7-deoxydoxorubicinone, were found associated with the niosomes in the plasma, possibly due to their adsorption to the vesicle surface once formed outside the niosome. Overall metabolite levels in the liver were increased when doxorubicin niosomes were administered compared to the drug in solution. A 5 mg kg^–1 injection of doxorubicin niosomes produced a terminal mean tumour weight that was similar to that obtained from animals administered 10 mg kg^–1 doxorubicin solution. Conclusions. Modest tumour targeting was achieved by the delivery of doxorubicin in sorbitan monostearate niosomes, increasing the tumour to heart AUC^0–24 ratio from 0.27 to 0.36 and a doubling of tumoricidal activity. The overall level of doxorubicin metabolites was also increased.     

The mechanism of the hypothermic effect of amantadine in rats and mice

Amantadine (25–100 mg kg^?1, i.p.) given to rats at an ambient temperature of 4°, or mice at 21°, caused a marked fall in rectal temperature. Prior administration of pimozide (1–2 mg kg^?1, s.c.) did not block hypothermia due to amantadine in rats or mice; in contrast, hypothermia due to apomorphine (2 mg kg^?1, i.p.) and piribedil (10–40 mg kg^?1, i.p.) in rats was blocked by pimozide pretreatment. Amphetamine (5 mg kg^?1, i.p.) given 2 h after reserpine (2 mg kg^?1, i.p.) caused a reversal of the hypothermic effect of reserpine in mice, but a reversal was not obtained with amantadine (50 mg kg^?1, i.p.). Direct injection of amantadine (4–8 mg kg^?1) into the cerebral ventricles (i.c.v.) of mice caused marked hypothermia which was not blocked by pimozide, but intravenous injection of the same dose of amantadine did not cause hypothermia. Rimantadine, a congener of amantadine but without anti-parkinsonian activity, also caused pimozide insensitive hypothermia in mice at doses of 50 mg kg^?1, intraperitoneally or 2–4 mg kg^?1, intracerebroventricularly. The main conclusion drawn from these results is that in causing hypothermia amantadine acts in the cns but not on dopamine receptors.     

Early metabolomics changes in heart and plasma during chronic doxorubicin treatment in B6C3F1 mice

The present study aimed to identify molecular markers of early stages of cardiotoxicity induced by a potent chemotherapeutic agent, doxorubicin (DOX). Male B6C3F₁ mice were dosed with 3 mg kg^?1 DOX or saline via tail vein weekly for 2, 3, 4, 6 or 8 weeks (cumulative DOX doses of 6, 9, 12, 18 or 24 mg kg^?1, respectively) and euthanized a week after the last dose. Mass spectrometry‐based and nuclear magnetic resonance spectrometry‐based metabolic profiling were employed to identify initial biomarkers of cardiotoxicity before myocardial injury and cardiac pathology, which were not noted until after the 18 and 24 mg kg^?1 cumulative doses, respectively. After a cumulative dose of 6 mg kg^?1, 18 amino acids and four biogenic amines (acetylornithine, kynurenine, putrescine and serotonin) were significantly increased in cardiac tissue; 16 amino acids and two biogenic amines (acetylornithine and hydroxyproline) were significantly altered in plasma. In addition, 16 acylcarnitines were significantly increased in plasma and five were significantly decreased in cardiac tissue compared to saline‐treated controls. Plasma lactate and succinate, involved in the Krebs cycle, were significantly altered after a cumulative dose of 6 mg kg^?1. A few metabolites remained altered at higher cumulative DOX doses, which could partly indicate a transition from injury processes at 2 weeks to repair processes with additional injury happening concurrently before myocardial injury at 8 weeks. These altered metabolic profiles in mouse heart and plasma during the initial stages of injury progression due to DOX treatment may suggest these metabolites as candidate early biomarkers of cardiotoxicity. Published 2016. This article is a U.S. Government work and is in the public domain in the USA     

Potent Antinociceptive Activity of a Hydroalcoholic Extract of Phyllanthus corcovadensis

Abstract— This study analyses the analgesic effect of a hydroalcoholic extract (HE) from Phyllanthus corcovadensis in several models of pain in mice. HE (3–60 mg kg^?1, i.p.) or (100–500 mg kg^?1, p.o.) caused a graded and potent analgesic effect against the abdominal constriction response caused by acetic acid and acetylcholine with an ID50 of about 3 and 100 mg kg^?1, respectively. In the tail-flick model HE (up to 500 mg kg^?1, p.o.) was without effect, while morphine (1–10 mg kg^?1, s.c.) caused a graded increase in pain latency (ID50, 3 mg kg^?1). HE (1–300 mg kg^?1) given both intraperitoneally and orally caused a potent and graded inhibition of the second phase of formalin-induced persistent pain in mice with an ID50 of 1 and 80 mg kg^?1, respectively. In contrast, morphine (1–5 mg kg^?1, s.c.) inhibited both phases of formalin-induced pain with an ID50 of 2·5 mg kg^?1. Indomethacin (1–10 mg kg^?1, i.p.) only inhibited the second phase of formalin-induced pain with an ID50 of about 3 mg kg^?1. The analgesic effect of indomethacin, but not that caused by morphine and HE was accompanied by a graded inhibition of formalin-induced mouse paw oedema. In addition, HE up to 1 g kg^?1 failed to prevent carrageenan- and dextran-induced rat hindpaw oedema. It is concluded that HE exhibits a potent antinociceptive profile, either when given intraperitoneally or orally. The mechanisms that underly its analgesic effect are unclear at present, but appear to be unrelated to inhibition of synthesis of arachidonic acid via cyclo-oxygenase or to activation of opioid receptors.     

Plasma pharmacokinetics and urinary and biliary excretion of a new potent tripeptide HIV-1 protease inhibitor,KNI-272, in rats after intravenous administration

The pharmacokinetic (PK) characteristics of KNI-272, a potent and selective HIV-1 protease inhibitor, were evaluated in rats after intravenous (IV) administration. The effect of dose on KNI-272 plasma kinetics, and the urinary and biliary elimination kinetics of KNI-272, were examined. After IV administration of 10.0 mg kg^?1 KNI-272, the mean terminal elimination half-life, t_1/2λz, was 3.49 ± 0.19 (SE) h, the total plasma clearance, CL_tot, was 15.1 ± 1.2 mL min^?1 and the distribution volume at steady state, V_d,ss, was 3790±280 mL kg^?1. On the other hand, after 1.0mg kg^?1 IV administration, t_d,ss, was 3.04±0.11 h, CL_tot was 15.9±0.2mL min^?1, and V_d,ss was 6950±600 mL kg^?1. The PK parameters of KNI-272 after IV administration showed that the disposition of KNI-272 in the rat plasma is linear within the dose range from 1.0 to 10.0mg kg^?1. Using an equilibrium dialysis method, the plasma binding of KNI-272 was measured in vitro. The free fractions were 17.7 ± 0.6%, 12.1±1.5%, and 13.8 ± 1.4% at the total concentration ranges of 9.898 ± 0.097 μg mL^?1, 0.888 ± 0.008 μg mL^?1, and 0.470±0.55 μg mL^?1, respectively. The percentages of the dose excreted into the urine and bile as the unchanged form were 1.20 ± 1.06% and 1.61 ± 0.32% at 1.0mg kg^?1 dose, and 0.164 ± 0.083% and 1.42 ± 0.26% at 10.0 mg kg^?1 dose, respectively. The renal clearance (CL_R) and the biliary clearance (CL_B) were calculated to be 0.191 and 0.256mL min^?1 for 1.0mg kg^?1, and 0.0248 and 0.215 mL min^?1 for 10.0 mg kg^?1, respectively. When comparing these values with the CL_tot values, the urinary and biliary excretion of KNI-272 are minor disposition routes.     

The distribution of doxorubicin in mice following administration in niosomes

Large multilamellar non-ionic surfactant vesicles (niosomes) with diameters of around 800-900 nm prepared from a C16 triglyceryl ether with and without cholesterol and containing doxorubicin (Adriamycin) were administered to S180 tumour-bearing NMRI mice by bolus injection. Although in-vitro drug release from cholesterol-containing niosomes is delayed, in-vivo there was little difference between the two preparations when plasma levels were compared. As previously observed, half-lives of the drug were prolonged compared with free solution profiles. Liver uptake was not significantly affected by niosome encapsulation of doxorubicin. There is minor accumulation of drug in the lung, perhaps because of aggregation of the vesicles and their physical entrapment. Tumour levels of drug were higher following administration of cholesterol-containing niosomes and this was reflected in the more effective reduction in tumour growth. Metabolism of doxorubicin is altered by niosomal administration, but more studies are required before the significance of the metabolic data can be assessed.     

Chemical and Pharmacological Studies of Phyllanthus caroliniensis in Mice

The aim of this study was to isolate and characterize the constituents of the hydroalcoholic extract (HE) of the leaves, stems and roots from P. caroliniensis, and also to evaluate the preliminary antinociceptive action of the HE and purified compounds in mice. Phytosterols, quercetin, gallic acid ethyl ester and geraniin were identified in P. caroliniensis on the basis of ¹H and ¹³C NMR spectral data and by mixed co-TLC and co-HPLC injection with authentic samples. The HE of P. caroliniensis (10-100 mg kg^?1, i.p.) inhibited, in a dose-related manner, acetic acid-induced abdominal constrictions in mice, with a mean ID50 value of 23.7 mg kg^?1. In the formalin test, the HE given intraperitoneally (1-30 mg kg^?1) or orally (25-600 mg kg^?1) caused graded inhibitions of both the neurogenic (first phase) and the inflammatory response (late phase) of formalin-induced licking. The HE was 54-fold more effective in inhibiting the late phase than it was in inhibiting the first phase of the formalin test, with mean ID50 values of 3.6 and 196.4 mg kg^?1, respectively. The HE failed, however, to affect the oedematogenic response associated with the late phase of formalin-induced pain. In addition, the reference drug, aspirin, given intraperitoneally (1-100 mg kg^?1) or orally (100-600 mg kg^?1), caused significant inhibition of the late but not the first phase of the formalin test. Pharmacological analysis also revealed that quercetin, gallic acid ethyl ester and a semi-purified fraction of flavonoids (1-100 mg kg^?1, i.p.) exhibited graded and significant antinociception against acetic acid-induced abdominal constriction. The mean ID50 values (mg kg^?1) for these effects were: 18.8, 34.7 and 5.3, respectively. It is concluded that quercetin, gallic acid ethyl ester and some as yet unidentified flavonoids might account for the antinociceptive action reported for the HE of P. caroliniensis.     

Effect of caffeine and nicotine on avoidance learning in mice: lack of interaction

Abstract— Tested alone, nicotine (0·25 or 0·5 mg kg^?1) improved shuttle-box avoidance learning in mice of the CD-1 strain. Caffeine had no effect at doses of 2·5 and 5 mg kg^?1 and impaired performance at a dose of 10 mg kg^?1. Combinations of the two drugs did not increase avoidance responses more than nicotine alone, nor was nicotine able to attenuate performance depression induced by the highest dose of caffeine. Lack of drug interaction in the avoidance test contrasts with the occurrence of interactive effects of the two drugs in a locomotor activity test. When given in combination, caffeine and nicotine increased locomotor activity at doses ineffective by themselves. The results seem to indicate no advantage in combining caffeine and nicotine to improve active avoidance learning.     

Effect of chlorpromazine on mouse ambulatory activity sensitization caused by (+)-amphetamine

Abstract— The development of sensitization to the ambulation-increasing effect of (+)-amphetamine (2·5 mg kg^?1) was found to be dose-dependently inhibited when 1 or 2 mg kg^?1 chlorpromazine was administered concomitantly, and the sensitization to (+)-amphetamine was almost completely suppressed when co-administered with 4 mg kg^?1 chlorpromazine. Following a challenge dose of 2·5 mg kg^?1 (+)-amphetamine, mice pretreated with (+)-amphetamine alone or with (+)-amphetamine plus 1 or 2 mg kg^?1 chlorpromazine showed similar marked enhancement of the sensitization. However, mice that had been given (+)-amphetamine plus 4 mg kg^?1 chlorpromazine displayed only slight enhancement of the effect compared with the activity level in saline-pretreated mice.     

Oral Toxicity Study of 2-Pentenenitrile in Rats with Reproductive Toxicity Screening Test

A combined repeated-dose toxicity study with reproduction was conducted with 2‐pentenenitrile (2-PN). Rats (10/sex per dose level) were dosed with 2-PN once daily by gavage at dose levels of either 0, 1, 3, or 10 mg kg^?1 day^?1 for 28 days, prior to and during cohabitation, and through day 3 of lactation. General clinical observations were recorded daily; body weights were recorded weekly. A neurobehavioral evaluation consisting of a functional observational battery and motor activity was conducted in all parental rats (10/sex per group). Clinical pathology parameters (hematology, clinical chemistry, coagulation) were measured in parental rats. Pup weights and clinical signs were recorded at birth and on lactation day 4. Parental rats were given a gross pathological examination, organ weights were obtained, and histological examination was conducted for the control and 10 mg kg^?1 day^?1 groups. No effects were seen with regard to mortality, clinical signs, functional observational battery and motor activity, hematology, or organ weights. Females receiving 10 mg/kg and males from all dose groups showed lower body weight gains and feed efficiency. Increased albumin concentrations were seen in both sexes given 10 mg/kg. Females in the 10 mg/kg group showed degeneration of the olfactory mucosa. No effects on the numbers of pups born, number surviving to lactation day 4, pup weight, and no gross anatomical development changes were observed. Under the conditions of this study, the no-observed-effect level (NOEL) for systemic toxicity in rats was 3 mg kg^?1 day^?1, based on degeneration of olfactory mucosa in females at 10 mg kg^?1 day^?1. The NOEL for reproductive and neurobehavioral toxicity in rats and for toxicity to offspring was 10 mg kg^?1 day^?1, the highest dose level tested.     

Reversal of chlorpromazine-induced avoidance depression by the N-methyl-d-aspartate antagonist,dizocilpine, in mice

Abstract— The non-competitive N-methyl-d -aspartate (NMDA) antagonist MK-801 (dizocilpine) was tested, alone or in combination with chlorpromazine, in mice previously trained in the shuttle-box. The lowest doses of dizocilpine (0·02 and 0·04 mg kg^?1) attenuated the disrupting action of the neuroleptic (1·5 mg kg^?1) on avoidance-performance, while avoidance depression induced by 1·5 and 2 mg kg^?1 chlorpromazine was completely or almost completely reversed by 0·08 mg kg^?1 NMDA antagonist. The highest dose (0·16 mg kg^?1) of dizocilpine did not ameliorate avoidance-performance of mice receiving 2 mg kg^?1 chlorpromazine, perhaps because of ataxic effects produced by the drug combination, at these doses. The results support suggestions for a potential use of NMDA antagonists in the treatment of extrapyramidal side-effects of neuroleptics.     

Mesulergine antagonism towards the fluoxetine anti-immobility effect in the forced swimming test in mice

Abstract— The anti-immobility effect of fluoxetine (40 mg kg^?1) in the forced swimming test in mice was antagonized by the 5-HT_1c/2 antagonist mesulergine (7·5 mg kg^?1) and the dopamine D₂ antagonist (±)-sulpiride (12.5 mg kg^?1) but not by the 5-HT_2/1C antagonist ritanserine (2 mg kg^?1), the 5-HT_1A/1B antagonist (–)-propranolol (20 mg kg^?1) or the 5-HT₃ antagonist DAU 6215 (0·1 mg kg^?1). All compounds were administered intraperitoneally (i.p.) 6 min before fluoxetine, given i.p. 30 min before testing. The anti-immobility effect of fluoxetine was also prevented by pretreat-ment with p-chlorophenylalanine (300 mg kg^?1 twice daily for 3 days) which produced an 80% reduction of 5-HT in brain. The results suggest that fluoxetine reduces immobility time in mice forced to swim, by acting indirectly through a mesulergine-sensitive site, probably the 5-HT_1C receptor.     

Dexamethasone Reduced Clonidine-induced Hypoactivity in Mice

Reduced clonidine anti-nociception in mice given low doses of dexamethasone has encouraged us to investigate the effects of dexamethasone pretreatment on locomotor hypoactivity, another example of clonidine-induced behaviour in mice. Dexamethasone administered intraperitoneally (0.1, 1.0, 10 mg kg^?1) 30 min before clonidine reduced clonidine-induced locomotor hypoactivity in the activity cage to an extent which was dose-dependent. Dexamethasone administered centrally (10 ng/mouse) 30 min before clonidine was also able to reduce clonidine-induced locomotor hypoactivity. Cycloheximide administered at a dose of 10 mg kg^?1 2 h before clonidine did not change the effects of clonidine but was able to prevent the effects of dexamethasone on clonidine-induced hypoactivity. The glucocorticoid receptor antagonist RU38486 administered centrally at the dose of 1 ng/mouse did not change the effects of clonidine, whereas it was able to block the effects of dexamethasone on clonidine-induced locomotor hypoactivity. These results suggest that the effects of dexamethasone on clonidine-induced locomotor hypoactivity depend on the stimulating effects that dexamethasone exerts on the protein synthesis via the glucocorticoid receptor in the brain.     

Buprenorphine-cocaine Interactions in Mice: Effect on Locomotor Activity and Hole-dipping Behaviour

Abstract— The effect of cocaine and the mixed μ-opioid partial agonist/κ-antagonist buprenorphine on locomotor activity and hole-dipping behaviour was investigated in mice. The drugs were given alone and in combination. Cocaine (7·5, 15, 30 mg kg^?1, i.p.) significantly increased locomotion in a dose-related manner in the hour following injection. The two highest doses also increased hole-dipping although this response was not consistently seen. Buprenorphine (0·5, 5 mg kg^?1, i.p.) produced an increase in locomotion which occurred 30–60 min after injection but did not alter hole-dipping behaviour. A lower dose (0·05 mg kg^?1) had no effect on either parameter. The locomotion induced by cocaine (15 mg kg^?1, i.p.) was not modified by buprenorphine (0·05, 0·5, 1, 5 mg kg^?1, i.p.; 5 min pretreatment). However, hole-dipping was almost completely abolished in animals given combinations of cocaine and buprenorphine (0·05–5 mg kg^?1, i.p.), although neither drug decreased hole-dipping when given alone. This observation, which was not simply due to the emergence of stereotyped behaviour, suggests an interaction between buprenorphine and cocaine.     

Asclepias Fruticosa

Context: Ficus racemosa Linn. (Moraceae) bark is a rich source of phenolic compounds having diverse biological properties including antioxidant activity. The present study evaluated the cardioprotective activity of sequential acetone extract of Ficus racemosa bark against doxorubicin-induced cardiotoxicity in rats.

Materials and methods: The extract was standardized by high-performance liquid chromatography (HPLC) and subjected to acute toxicological evaluation in mice. Cardiotoxicity was induced by administration of doxorubicin (10?mg kg^?1 i.v.) to the extract pretreated rats (250 and 500?mg kg^?1) and compared with that of Arjuna, a standard cardiotonic. Biochemical parameters included CK-MB, LDH, AST, ALT, troponin I, thiobarbituric acid reactive substances (TBARS), and glutathione.

Results: The HPLC fingerprinting of the extract indicated the presence of bergenin (0.89%) and bergapten (0.07%). In an acute toxicity study, the extract at a dose of 2?g kg^?1 did not cause any adverse changes and no mortality was observed. Administration of doxorubicin significantly increased (p?≤?0.05) serum levels of creatine kinase, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase, which were decreased to an extent of 68, 63, 41, and 65%, respectively, in extract pretreated group (500?mg kg^?1). Troponin I was undetected in control group, while it was found in serum of all the experimental groups. The extract pretreatment significantly decreased (p?≤?0.05) TBARS and increased glutathione levels in serum and cardiac tissue. These observations were further substantiated by the histopathological studies.

Conclusion: The acetone extract of F. racemosa bark possesses potential cardioprotective activity against doxorubicin-induced cardiotoxicity in rats by scavenging free radicals generated by the administration of the drug.     

Reduction in blood pressure in normal and spontaneously hypertensive rats by lergotrile mesylate

The acute administration of lergotrile mesylate to normal or spontaneously-hypertensive rats (SHR) causes a prompt reduction in blood pressure. In SHR, doses as small as 0·05 mg kg^?1 are effective; maximal reductions in blood pressure are obtained at a dose of 0·25 mg kg^?1. Lergotrile may be administered intraperitoneally or orally. Its efficacy as an antihypertensive agent in rats does not diminish significantly when administered twice daily for 7 days. Although lergotrile has been reported to be a dopamine agonist, the present data do not establish the mechanism by which the drug lowers blood pressure.     

Kinetics of Bupivacaine After Levcromakalim Treatment in Mice

Previous workers have reported that 0.01 mg kg^?1 of levcromakalim injected intraperitoneally did not modify bupivacaine-induced neurotoxicity but increased the duration of action of bupivacaine. This study was designed to document possible changes in the pharmacokinetic behaviour of bupivacaine and its main metabolite, N-desbutylbupivacaine in mice after a single 0.01 mg kg^?1 intraperitoneal injection of levcromakalim. The kinetic parameters of bupivacaine were determined after a single 20 mg kg^?1 intraperitoneal injection of bupivacaine in controls and in levcromakalim-treated mice. It was found that levcromakalim did not change any kinetic parameters of bupivacaine or of its main metabolite, N-desbutylbupivacaine. The previously reported findings of the influence of the low dose (0.01 mg kg^?1) of levcromakalim on bupivacaine-induced toxicity agree well with the lack of influence of 0.01 mg kg^?1 of levcromakalim on bupivacaine and N-desbutylbupivacaine pharmacokinetics, although the reported increase in the duration of action of bupivacaine after levcromakalim treatment can hardly be explained by the pharmacokinetics of bupivacaine when associated with levcromakalim. We suggest that levcromakalim might interfere directly with ion-channel block caused by bupivacaine by altering conduction properties or indirectly by enhancing bupivacaine-induced voltage and time-dependent sodium-channel block.     

Effect of metadoxine on striatal dopamine levels in C57 Black mice

Abstract— In the present study, we examined the effect of metadoxine on striatal levels of dopamine, 5-hydroxytryptamine (5-HT) and their metabolites in male C57 Black mice. Striatal content was assayed after systemic administration of metadoxine ranging from 1 μg kg^?1 to 500 mg kg^?1. Striatal dopamine increased 1 h after treatment with metadoxine (150 mg kg^?1), but the most notable effect was obtained 24 h after the drug administration. At this time a plateau was reached; the two major metabolites of dopamine showed the same trend. Seven days after metadoxine administration, striatal dopamine approached the control values. Over the same time intervals, striatal 5-HT increased to a lesser extent and 5-hydroxy-indoleacetic acid did not differ significantly from controls. Striatal dopamine increased significantly at a dose of 250 μg kg^?1 up to a dose of 1 mg kg^?1 metadoxine; no further increment was observed between 1 and 500 mg kg^?1 metadoxine. Administration of each component at doses equimolar to 1 mg metadoxine showed that pyridoxine produced only a mild increase in striatal dopamine compared with controls. We suggest that the metadoxine-induced striatal dopamine increase is obtained by increasing synthesis of dopamine.     

Effect of borneol on the distribution of gastrodin to the brain in mice via oral administration

Both borneol and gastrodin are bioactive substances derived from traditional Chinese medicine. In this paper, the effect of borneol on the distribution of gastrodin to the brain in mice via oral administration was investigated. Gastrodin concentrations in plasma and gastrodigenin (active metabolite of gastrodin) concentrations in the brain of mice were determined by reversed-phase high-performance liquid chromatography, after intragastric administration of gastrodin (200 mg kg^{? 1}) alone or combined with different doses (200, 400 and 600 mg kg^{? 1}) of borneol simultaneously or the same dose (400 mg kg^{? 1}) of borneol given 20 and 40 min beforehand, respectively. Compared with the administration of gastrodin alone, gastrodin coadministrated with borneol could have been rapidly absorbed from the gastrointestinal tract; the peak time of gastrodin in the plasma became shorter (5–15 vs. 30 min); the bioavailability of gastrodigenin in the brain was increased by 33.6–108.8%; and obvious brain-targeting effect was observed. The enhancing effect was attenuated when the dose of borneol was too high (600 mg kg^{? 1}), or the time interval between the administration of borneol and gastrodin was longer than 40 min. The results indicate that borneol can accelerate the absorption of gastrodin in the gastrointestinal tract and promote its distribution to the brain. Therefore, borneol is a promising promoter for oral brain-targeting drug delivery.     

Antinociceptive Effect of the Hydroalcoholic Extract of Bauhinia splendens Stems in Mice

The analgesic effect of the hydroalcoholic extract of the stems of Bauhinia splendens (Leguminosae) has been investigated in chemical and thermal models of nociception in mice. The hydroalcoholic extract of B. splendens, 3–60 mg kg^? intraperitoneally or 50–400 mg kg^? orally, caused dose-related, and long-lasting (up to 3 h) inhibition of acetic acid-induced abdominal constriction in mice, with ID50 values of 3.2 and 177.6 mg kg^? and maximum inhibition of 95 ± 2 and 61 ± 6%, respectively. In the formalin test, the extract given intraperitoneally (1.60 mg kg^?) or orally (50–400 mg kg^?) caused graded inhibition of both phases of formalin-induced pain, being about 5- to 6-fold more potent in attenuating the second phase of pain. The calculated mean ID50 values for the first and the second phases were 11.5 and 2.5 mg kg^?, respectively, for intraperitoneal administration and > 200 and 70 mg kg^?, respectively, for oral administration; the percentages of maximum inhibition for the first and the second phases were 68 ± 6 and 99 ± 1, respectively, for intraperitoneal administration and 37 ± 6 and 69 ± 9, respectively, for oral administration. However, at the same doses the extract did not significantly affect the oedematogenic response induced by formalin. The treatment of animals with naloxone (5 mg kg^?, i.p.) completely reversed the analgesic effect caused by morphine (5 mg kg^?, s.c), but had no effect against the antinociceptive effect of the hydroalcoholic extract of B. splendens (60 mg kg^?, i.p.) when assessed against acetic acid-induced abdominal constrictions. Furthermore, the extract, in contrast with morphine, had no analgesic effect in the hot-plate test. These data show that the hydroalcoholic extract of B. splendens has significant analgesic action when assessed against several models of pain. The mechanism underlying its analgesic effect still remains unknown, but seems to be unrelated to interaction with opioid systems.