An improved method for toxicological profiling of chemical substances.

Toxicity profiling is an integral part of the drug discovery pipeline. The 3Rs principle-Replacement, Reduction, and Refinement, is considered a golden rule in determining the most appropriate approach for toxicity studies. The acute toxicity study with proper estimate of median lethal dose (LD50) is usually an initial procedure for the determination of most suitable test doses for preclinical toxicological and pharmacological profiling. Several methods, which have been devised to determine the LD50, are faced with the challenge of using a large number of animals and time constraints. Despite the inherent advantage of the newer OECD Test Guidelines, the increasing concerns among toxicologists, the regulatory authorities and the general public, on the need to adhere to 3Rs principle, necessitated the need for an improved approach. Such an approach should not only minimize the time and number of animals required, but also take into cognizance animal welfare, and give accurate, comparable, and reproducible results across laboratories. While taking advantage of the inherent merits of the existing methods, here is presented the mathematical basis and evaluation of an improved method for toxicity profiling of test substances and estimation of LD50. The method makes use of the generated Table of values for the selection of appropriate test doses. Our proposed method has capacities to optimize the time and number of animal use, ensure more reliable and reproducible results across laboratories, allow for easy selection of doses for subsequent toxicity profiling, and be adaptable to other biological screening beyond toxicity studies.

Mucuna pruriens seed repeals the hypothalamic-pituitary-testicular axis disruption following carbamazepine treatment in male Wistar rats.

This study examined the potential effects of Mucuna pruriens (MP) seed powder on the disruptions of the hypothalamic-pituitary-testicular axis caused by the carbamazepine (CBZ) treatment in male Wistar rats. A total of 35 male Wistar rats were randomized into 5 groups (n=7). The animal in group 1 received normal saline (0.2 ml) orally, while groups 2-5 received carbamazepine (CBZ) 25 mg/kg per oral. Groups 1, and 2 were fed with standard rats' chow, while groups 3-5 rats were supplied with a diet containing MP seed powder at 2.25 g, 1.5 g, and 0.75 g respectively. The serum level of male reproductive hormones, estradiol, seminal profiles, and histoarchitecture of the hypothalamus, pituitary, and testis was delineated. Descriptive and inferential statistics were used to analyze the result. There was a marked decrease in the testicular weight, follicle-stimulating hormone, testosterone concentration, and normal sperm cells in the CBZ, and CBZ + MP (2.25 mg/kg) treatment groups.  There was a marked increase in the testicular tissue lipid peroxidation in the CBZ, and CBZ + MP (g) treated rats in addition to various morphological alterations in the hypothalamus, pituitary, and testis. These anomalies were receded in the CBZ + MP (1.5 g), and CBZ + MP (0.75 g) treatment groups. Consumption of MP (1.5 g, and 0.75 g) may alleviate the injurious effects of CBZ treatment on the hypothalamic-pituitary-testicular functions.

Mucuna pruriens seed protects the hippocampal neurons and abrogates seizure indices in chemically-convulsed mice: Evidence of the Nrf2 expression defense pathway.

The anti-convulsant mechanisms and neuroprotective effects of Mucuna pruriens (MP) seed in male BALB/c mice were evaluated. Ninety mice were kindled with picrotoxin, strychnine, or pilocarpine hydrochloride at the 30th minute of intraperitoneal injection (i.p) of normal saline (0.2 ml), MP (200, 100, 50 mg/kg), diazepam (7.5 mg/kg), or haloperidol (5 mg/kg). The onset of convulsion and percentage mortality was recorded. The histoarchitectural and immunohistochemical profiles of the brains were determined. Data were expressed as mean ± SEM with a one-way analysis of variance (ANOVA), while p < 0.05 was considered significant. There was a significant prolongation of the latency to first seizure across the treatment groups following picrotoxin, and pilocarpine-induced convulsion; a decrease in percentage mortality in the MP (50 mg/kg) treatment group, and an increase in the hippocampal nuclear factor erythroid 2-related factor 2 count, and Neu-N expression in the MP (200 mg/kg, and 100 mg/kg) treated mice. Treatment with MP seed may abolish seizure occurrence and consequential mortality; mechanisms traceable to its GABAergic expression and hippocampal NRF 2 and Neu N expression.

Preliminary assessment of proanthocyanidin isolates of Vitis vinifera seed on the central nervous system of male Albino mice.

This study evaluated the potential neurobehavioral effects of proanthocyanidin-rich-fraction (PRF) obtained from Vitis vinifera seed in male Albino mice. Adult (2½- to 3-month old) male Albino mice were treated with PRF (200, 100, 50 mg/kg) and subjected to diverse behavioral models specially designed for the assessment of central nervous system-acting agents. One-shot intraperitoneal (i.p) injection of PRF (200 and 100 mg/kg) decreased the rectal temperature, exploratory activities (locomotion, rearing, and grooming), anxiety-like responses (% open-arm time, open-arm entries but decreased the total number of enclosed arm times). However, acute i.p administration of PRF decreased the total score of apomorphine-induced stereotyped behaviors, latency to hexobarbitone-induced sleep, and increased the total sleep duration. Moreover, indices of convulsion (tonic flexion, extension, clonic convulsion, stupor, and recovery time) were decreased in the PRF treatment groups, especially the PRF (50 mg/kg)-treated mice. Based on these present findings, it could therefore be inferred that systemic administration of PRF of V. vinifera seed origin induces diverse modification on the behaviors of the treated mice stemming from anxiolytic, anticonvulsant, sedative, and decrease in core temperature.

Proanthocyanidin from Vitis vinifera attenuates memory impairment due to convulsive status epilepticus.

This study investigated the effects of proanthocyanidin-rich fraction (PRF) of Vitis vinifera seed extract on the markers of hippocampal-dependent memory in convulsive status epilepticus (CSE) rat model. One hundred juvenile Wistar rats were randomized into 6 groups. Group 1 (n = 10) received propylene glycol (PG 0.1 ml/100 g) intraperitoneally (i.p), while convulsion was induced in groups 2-6 (n = 18 each) using lithium (127 mg/kg i.p) and pilocarpine hydrochloride (40 mg/kg i.p). The established CSE rats in groups 2-6 received a daily treatment of PG (0.1 ml i.p), PRF (30 mg/kg i.p), PRF (20 mg/kg BW i.p), PRF (10 mg/kg BW i.p) or diazepam (5 mg/kg BW i.p) for seven days. Thereafter, they were kept untreated but with access to feed and water for 21 days. The control and CSE-treated rats were subjected to behavioral tests, while the biochemical and histomorphological evaluations of the hippocampus were done after the sacrifice. The results were presented as mean ±â€¯SEM in graphs or tables. The level of significance was considered when p < 0.05. There was significant decrease in the hippocampal-dependent memory, hippocampal weight and an increased malondialdehyde concentration following CSE. The activities of acetylcholinesterase decreased significantly in the PRF-treated CSE rats. The hippocampal glial cells and granule count increased significantly following CSE, with various neurodegenerative features in the CA1 of the hippocampus. These derangements were attenuated significantly following PRF treatment. Memory impairment following CSE may be attenuated with the administration of PRF from V. vinifera seed in rats.

Anticonvulsant and neuroprotective effects of carbamazepine-levetiracetam adjunctive treatment in convulsive status epilepticus rat model: Inhibition of cholinergic transmission.

This study evaluated the anticonvulsant and neuroprotective effects of carbamazepine (CBZ), levetiracetam (LEV), and CBZ + LEV adjunctive treatment in convulsive status epilepticus (CSE) rat model. Twenty-five male Wistar rats were randomized into five groups (n = 5). Groups I and II received 0.2 ml of normal saline intraperitoneally (i.p), while groups III-V received CBZ (25 mg/kg i.p), LEV (50 mg/kg i.p) or combination of sub-therapeutic doses of CBZ (12.5 mg/kg i.p) and LEV (25 mg/kg i.p). Thirty minutes later, seizure was kindled with pilocarpine hydrochloride (350 mg/kg) in group II-V rats. Seizure indices, markers of excitotoxicity, and astroglioses were determined, while the hippocampal morphometry was also evaluated. The data was analysed using descriptive and inferential statistics, while the results were presented as mean ± SEM in graphs or tables, and the level of significance was taken at p < 0.05. The anticonvulsant treatments delayed the inception of seizure indices (p = 0.0006), while the percentage mortality decreased significantly (p = 0.0001) in all the treatment groups. The hippocampal concentrations of acetylcholine, malondialdehyde, and tissue necrotic factor-alpha decreased significantly (p = 0.0077) in all the treated group relative to the positive control. The reactive astrogliosis in the hippocampus (CA 1) increased significantly (p = 0.0001) compared with the control but abrogated in all the treatment groups relative to the positive control. The anticonvulsant and neuroprotective effects are in this order: LEV < CBZ + CBZ < CBZ. The drug efficacy is attributable to the inhibition of cholinergic transmission.

The impairment of motor coordination following chronic carbamazepine-levetiracetam combination treatment with evidence of corticocerebellar toxicity in male Wistar rats.

This study examined the effects of carbamazepine (CBZ) or levetiracetam (LEV) and sub-therapeutic doses of the combination of the two conventional antiepileptics on some of the markers of motor coordination. Twenty-four male Wistar rats (140 ± 5 g) were randomized into 4 groups (n = 6). Group I rats received physiological saline (0.2 ml), group II were administered CBZ (25.0 mg/kg), group III received LEV (50 mg/kg), while group IV rats were given sub-therapeutic doses of CBZ (12.5 mg/kg) and LEV (25 mg/kg) intraperitoneally for 28 days. Thereafter the animals were subjected to behavioral and biochemical investigations, while the frontal lobe and cerebellar tissue were preserved for histological investigation. Data were subjected to descriptive and inferential statistics, and the results presented as mean ± SEM, analyzed using one-way Analysis of variance (ANOVA) and Student- Newman Keuls post hoc analysis where appropriate. p < 0.05 was considered statistically significant. There was significant alteration in fine and skilled movement after the CBZ, and CBZ + LEV chronic treatment compared with the control. The CBZ, and CBZ + LEV combination treatment increased the frontal lobe and cerebellar activities of acetylcholinesterase, malondialdehyde concentration, tissue necrotic factor alpha and decreased the activities of super oxide dismutase relative to the control. Disorganization of the histoarchitecture of the frontal lobe and cerebellum was characterized by cellular atrophy, chromatolysis and hyalinization. Chronic CBZ, and CBZ + LEV combination treatment produced psychomotor dysfunction and neurotoxicity in this order CBZ + LEV > CBZ > LEV in the rats.

Assessment of the biomarkers of hepatotoxicity following carbamazepine, levetiracetam, and carbamazepine-levetiracetam adjunctive treatment in male Wistar rats.

OBJECTIVE: This study examined some of the biomarkers of hepatotoxicity following chronic treatment with carbamazepine (CBZ), levetiracetam (LEV), and CBZ + LEV adjunctive treatment in male rats. METHOD: Twenty-four male Wistar rats (140-150 g) were randomized into four groups (n = 6) to receive oral dose of normal saline (0.1 mL), CBZ (25 mg/kg), LEV (50 mg/kg) or sub-therapeutic dose of CBZ (12.5 mg/kg) together with LEV (25 mg/kg) for 28 days. Activities of the liver enzymes and oxidative stress markers were determined while liver histomorphology was also carried out. Data were analyzed using descriptive and inferential statistics. The results were presented as mean ± SEM in graphs or tables, while the level of significance was taken at p < 0.05. RESULTS: The activities of alkaline-phosphatase and malondialdehyde concentrations increased significantly in all the drug treatment groups, while the activities of superoxide dismutase decreased significantly following CBZ, and CBZ + LEV treatment. Alanine-aminotransferase activities increased significantly in the CBZ and CBZ + LEV treated rats compared with control. The liver section of CBZ treated rats showed mild vascular congestion. CONCLUSION: None of these AEDs treatment is devoid of hepatotoxicity. However, the adverse effects in CBZ were greater than LEV, or CBZ + LEV adjunctive treatment.

Graded doses of grape seed methanol extract attenuated ataxic movement, cerebellocortical toxicity, and impairment following chronic carbamazepine treatment in male Wistar rats.

This study investigated the effects of chronic cotreatment of carbamazepine (CBZ) with grape seed methanolic extract (GSME) on the markers of neurotoxicity and motor coordination in male rats. Thirty male Wistar rats were randomized into 5 groups (n = 6) and treated orally with propylene glycol (PG 0.1 ml/day), CBZ (25 mg/kg), CBZ (25 mg/kg) + GSME (200 mg/kg), CBZ (25 mg/kg) + GSME (100 mg/kg), or CBZ (25 mg/kg) + GSME (50 mg/kg) for 28 days. Thereafter, the animals were subjected to motor-coordination tests and, eventually, sacrificed by cervical dislocation. The cranium was opened and the brain excised. The prefrontal cortex (PFC) and cerebellum were homogenized for the biochemical assessment, while representative brain was fixed in 10% neutral-buffered formalin for the histomorphological investigation. The results were presented as mean ±â€¯SEM, analyzed using one-way analysis of variance (ANOVA) and Student-Newman-Keuls post hoc analysis where appropriate, while p < 0.05 was considered statistically significant. Indices of motor coordination were significantly (p = 0.0014) impaired with a significant (p = 0.0001) increase in the concentration of malondialdehyde (MDA) in the PFC and cerebellar tissue. In addition, the activities of glutathione increased (p = 0.0001) significantly in the CBZ + GSME-treated rats. All these anomalies were attenuated in the CBZ + GSME treated rats. Coadministration of GSME with CBZ may ameliorate CBZ-induced neurotoxicity, histoarchitectural disorganization of PFC and cerebellum with resultant effect on fine motor actions.

Graded doses of grape seed methanol extract attenuated hepato-toxicity following chronic carbamazepine treatment in male Wistar rats.

AIM: This study investigated the effects of co-administration of carbamazepine (CBZ) with grape (Vitis vinifera) seed methanolic extract (GSME) on liver toxicity. METHOD: Thirty-five male rats (145-155 g) were randomized into 5 groups (n = 7) and administered with propylene glycol (PG 0.1 mL/day), CBZ (25 mg/kg), CBZ (25 mg/kg) + GSME (200 mg/kg), CBZ (25 mg/kg) + GSME (100 mg/kg), or CBZ (25 mg/kg) + GSME (50 mg/kg) orally for 28 days. Twenty-four hours after the last dose, changes in the body weights were determined. The rats were euthanized by cervical dislocation. The liver was weighed and later homogenized; while the supernatant was analyzed biochemically. The liver tissues were preserved in 10 % neutral-buffered formalin for the histomorphological investigation. RESULT: There was significant (p = 0.0001) decrease in the body weight following carbamazepine treatment. The relative liver weight also decreased significantly (p = 0.0004) across the treatment group compared with control. The activities of the liver enzymes (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and glutathione activities), including the concentrations of malondialdehyde, increased significantly (p ≤ 0.0004) following carbamazepine treatment. Various morphological alterations were observed, especially in the photomicrograph of the CBZ treated rats. However, these derangements were attenuated significantly in the CBZ - GSME co-treated group. CONCLUSION: This study concludes that GSME treatment may serve as a potential therapeutic agent in carbamazepine-induced hepatotoxicity/ dysfunction.

Biochemical, hematological and histopathological evaluation of the toxicity potential of the leaf extract of Stachytarpheta cayennensis in rats.

BACKGROUND AND AIM: The many pharmacological potentials of Stachytarpheta cayennensis (L.C. Rich) Vahl, especially in managing central nervous system disorders, hypertension, diabetes and infections, have made it a subject of abuse, necessitating the need to ascertain its safety. This study therefore investigated the toxic effects of the leaf extract of S. cayennensis in rats following acute and 28-day repeated doses in male and female rats. EXPERIMENTAL PROCEDURE: Acute and repeated dose studies were conducted in male and female groups of rats (135-150 g), using OECD 423 and 407 Tests guidelines respectively. Functional observational battery, and body weights were monitored. Blood samples were analysed for haematological and plasma biochemical indices. Organs (brain, kidneys and liver) specimen were collected and weighed. Kidney and liver specimen were subjected to histopathological analysis. RESULTS AND CONCLUSION: The LD50 of the extract was greater than 5000 mg/kg, p.o. (24 h) suggesting that the extract may be non-toxic. However, following single and repeated doses, the results revealed varying degree of significant (p < 0.05) changes in biochemical and heamatological indices, as well as in relative body weight and organ-body and organ-brain weight ratios. Also, histological assessment revealed evidence of liver and kidney toxicities and recovery was incomplete, as signs of toxicities were still evident after 21 days of recovery. Therefore, the extract is potentially harmful to vital organs with evidence of sex differential adverse effects and non-reversible forms of toxicity, especially with repeated usage, necessitating the need to avoid indiscriminate use.

Hypothalamic-pituitary-testicular axis derangement following chronic phenytoin-levetiracetam adjunctive treatment in male Wistar rats.

The effects of phenytoin (PHT), levetiracetam (LEV) or their adjunctive treatment on the hypothalamic-pituitary-testicular axis in male Wistar rats were determined. Twenty-eight male rats (150-180 g) were randomised into four groups (N = 7). Groups I to IV received intraperitoneal treatment of either normal saline (0.2 ml i.p) or PHT (50 mg/kg i.p) or LEV (50 mg/kg) or PHT (25 mg/kg) and LEV (25 mg/kg) combination for 28 days. The organ weight, concentrations of reproductive hormones and semen profile were determined, while the brain, epididymis and testis were preserved in 10% neutral-buffered formalin for the histomorphological study. Data were analysed using descriptive and inferential statistics. The results were presented as mean ± SEM in graphs or tables, while the level of significance was taken at p < .05. The semen profile was altered significantly in all the treatment groups. The gonadotrophic releasing hormone, luteinising hormone and testosterone concentration decreased significantly in the PHT- and PHT + LEV-treated groups compared with control. There were various disruptions in the hypothalamus, pituitary and testis of the PHT- and PHT + LEV adjunctive-treated rats. In conclusion, chronic PHT + LEV treatment may pose deleterious effects on the hypothalamic-pituitary-testicular axis than single treatment of either of the two drugs in male rats.

Carbamazepine adversely altered the pituitary-testicular axis with resultant reproductive dysfunctions than levetiracetam or carbamazepine-levetiracetam adjuvant treatment in male Wistar rat.

This study investigated the on-toward reactions of individual or adjunctive treatment with carbamazepine (CBZ) and levetiracetam (LEV) on the pituitary-testicular axis in male rats. Twenty-four male Wistar rats were randomised into 4 groups (n = 6) and received daily intraperitoneal (i.p) treatment of normal saline (0.1 ml/day); CBZ (25 mg/kg i.p); LEV (50 mg/kg i.p); or combination of CBZ (12.5 mg/kg) and LEV (25 mg/kg) for 4 weeks. The serum concentration of luteinising hormone (LH), follicle-stimulating hormone (FSH), and testosterone was determined. Also, the seminal profile and histomorphological status of the testis were determined. Data were analysed using descriptive and inferential statistics. The control and test groups were compared using Student's t test, analysis of variance (ANOVA), and Student-Newman-Keuls post hoc analysis where appropriate, while the results presented as mean ± SEM in graphs or tables. The level of significance was taken at p < .05. The percentage motility, viability, and concentration of FSH decreased significantly in all the treatment groups, while the testis was presented with various forms of histomorphological aberrations. This study concludes that CBZ, and CBZ + LEV adjunctive treatments alter the pituitary-testicular axis with evidence of hormonal deregulation and alteration in the reproductive functions' indices, while LEV treatment remains the safest.

Therapeutic Potentials and Cytochrome P450-Mediated Interactions Involving Herbal Products Indicated for Diabetes Mellitus.

BACKGROUND: There has been an increase in the use of herbal products to complement conventional drugs in the treatment of various diseases especially in developing countries. This may be attributable to the potential cost-effectiveness and ease of accessibility of these products as well as the perception of their safety profiles. However, there are numerous literature reports on herbs altering the pharmacokinetics and pharmacodynamics of other co-administered drugs thereby modulating the therapeutic outcomes. The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health. OBJECTIVE: It is important that knowledge on specific effects of antidiabetic herbs and their products on drug metabolizing enzymes are updated and documented so as to ensure optimization of their therapeutic utility. This review, therefore, aims to highlight herbal products with evidence-based antidiabetic effects, identify their bioactive phyto-constituents, and also focus on the important Cytochrome P450 and consequences of their inhibition or induction. METHODS: An extensive literature search was undertaken and the information obtained were critically analyzed and discussed. RESULTS AND CONCLUSION: The literature abounds with reports on the utilization of herbal medications for the treatment of diabetes mellitus since time immemorial, but very few of these herbal products have undergone clinical trials. Also, studies on the herb-drug interactions were limited. Due to the complex phytochemical composition of the herbs, concomitant administration with conventional drugs resulted in alterations of pharmacological effects of some drugs. Evidences of beneficial interactions were identified for medical exploitation.

Chronic administration of gabapentin and a gabapentin-carbamazepine combination reversibly suppress testicular function in male Wistar rats (Rattus norvegicus).

The effect of chronic administration of gabapentin, carbamazepine or a gabapentin-carbamazepine combination on testicular function in male rats was investigated to determine the effect of combining reduced doses of anti-epileptic drugs on the management of seizures, particularly with respect to the testis sequellae of chronic anti-epileptic administration. Male rats were randomized into four groups (n=10). Each group received daily intraperitoneal (i.p.) injections for 28days as follows: Group I, normal saline 0.1mL/day; Group II, gabapentin (GBP) 16mg/kg/day; Group III, carbamazepine (CBZ) 20mg/kg/day; and Group IV, sub-therapeutic doses of both GBP (8mg/kg) and CBZ (10mg/kg)/day. Twenty-four hours after the last treatment, five rats from each group were sacrificed and the remaining rats were allowed to recover for another four weeks. Sperm characteristics, serum testosterone, and histological integrity of the testis was assessed 24h after treatment and after 28days of drug withdrawal. GBP, CBZ, and GBP-CBZ combination significantly reduced the absolute weight of the testis, epididymis, and seminal vesicle (p<0.05). Moreover, epididymal sperm count and morphology were significantly decreased (p<0.05) in GBP, CBZ, and GBP-CBZ groups. Reduction in serum levels of testosterone for all of the treated groups was statistically significant (p<0.05). The cytoarchitecture of the testicular tissue in the testis of CBZ and GBP-CBZ groups showed disorganization. The altered testicular function were almost restored in GBP treated rats. CBZ and GBP-CBZ combination have delayed but reversible antifertility in the rats. Hence, chronic administration of GBP, CBZ, and GBP-CBZ combination reversibly reduced testicular function in male rats.

Caffeine and sleep-deprivation mediated changes in open-field behaviours, stress response and antioxidant status in mice.

OBJECTIVES: Effects of daily caffeine consumption on open-field behaviours, serum corticosterone and brain antioxidant levels were investigated after six hours of total sleep-deprivation in prepubertal mice. We tested the hypothesis that daily caffeine consumption may significantly alter behaviour, stress and antioxidative response of prepubertal mice to an acute episode of total sleep-deprivation. METHODS: Prepubertal Swiss mice of both sexes were assigned to two main groups of 120 each (subdivided into 6 groups of 10 each, based on sex), and administered vehicle or graded oral doses of caffeine (10, 20, 40, 80 and 120 mg/kg/day) for 14 days. On day 14, a main group was subjected to 6 h of total sleep-deprivation by 'gentle-handling'. Open-field behaviours were then assessed in both groups, after which animals were euthanized, and levels of corticosterone, superoxide dismutase and glutathione peroxidase assayed. RESULTS: Horizontal locomotion, rearing and grooming increased significantly, compared to control, with sleep-deprived (SD) mice showing stronger caffeine-driven responses at higher doses; and SD female mice showing sustained response to caffeine, compared to respective males. Plasma corticosterone increased with increasing doses of caffeine in both non sleep-deprived (NSD) and SD mice; although SD mice had higher corticosterone levels. Sleep-deprivation and/or higher doses of caffeine were associated with derangements in brain antioxidant levels. CONCLUSION: Repeated caffeine consumption and/or acute sleep-deprivation led to significant changes in pattern of open-field behaviour and stress/antioxidant response in mice. Responses seen in the study are probably due to modulatory effects of caffeine on the total body response to stressful stimuli.

Caffeine/sleep-deprivation interaction in mice produces complex memory effects.

BACKGROUND: Sleep deprivation negatively impacts memory, causing deficits in memory processes. Of interest is any agent that can offset such deficits. Mice were given varying doses of caffeine for 14 days and then deprived of sleep for 6 hours by the 'gentle handling' method. Memory was assessed using the Novel Object Recognition Test and Y maze alternation. PURPOSE: The study was designed to ascertain the impact of varying doses of caffeine combined with total sleep-deprivation on spatial and non spatial memory in mice. METHODS: Adult Swiss Webster mice of both sexes were assigned to six groups viz., vehicle (distilled water), or one of five selected doses of caffeine (10, 20, 40, 80 and 120 mg/kg) for 14 days via the oral route. Open field novel object recognition test and Y maze spatial working memory tests were carried out on day 14. Results were analysed using multi-factorial ANOVA followed by Tukey HSD test and expressed as mean ± S.E.M, with p values less than 0.05 were considered statistically significant. RESULTS: Novel object recognition tests (NOR) revealed that pre-training and pre-test sleep deprivation and caffeine combination impaired non spatial and spatial memory in male and female mice. CONCLUSION: The study shows the complex interactions with memory that may arise when total sleep deprivation is superimposed on caffeine administration.

Foraging enrichment modulates open field response to monosodium glutamate in mice.

BACKGROUND: Environmental enrichment can enhance expression of species-specific behaviour. While foraging enrichment is encouraged in laboratory animals, its impact on novelty induced behaviour remain largely unknown. PURPOSE: Here, we studied behavioural response of mice to acute and subchronic oral monosodium glutamate (MSG) in an open field with /without foraging enrichment. METHODS: Adult male mice, assigned to five groups were administered vehicle (distilled water), or one of four selected doses of MSG (10, 20, 40 and 80 mg/kg) for 21 days. Open field novelty induced behaviours i.e. horizontal locomotion, rearing and grooming were assessed after the first and last doses of MSG. Results were analysed using MANOVA followed by Tukey HSD multiple comparison test and expressed as mean ± S.E.M. RESULTS: Following acute MSG administration without enrichment, locomotor activity reduced, grooming increased, while rearing activity reduced at lower doses and increased at higher doses. Subchronic administration without enrichment was associated with increased locomotor activity and reduction in grooming, rearing activity however still showed a biphasic response. Addition of enrichment with acute administration resulted in sustained reduction in locomotor and rearing activities with a biphasic grooming response. Subchronically, there was reduction in horizontal locomotion, biphasic rearing response and sustained increase in grooming activity. CONCLUSION: Behavioural response to varying doses of MSG as observed in the open field is affected by modifications such as foraging enrichment, which can reverse or dampen the central effects seen irrespective of duration of administration.

Sedative and anxiolytic effects of the extracts of the leaves of Stachytarpheta cayennensis in mice.

The leaves are used ethnomedicinally in Nigeria and other parts of the world for insomnia and anxiety among other uses. The investigations sought scientific evidence for the ethnomedicinal use of the leaves for the management of insomnia and anxiety as well as the neural mechanisms for the activities. The sedative and anxiolytic effects of the extracts of the leaves of Stachytarpheta cayennensis were examined in this study. The methanolic extract (5-50 mg/kg, i.p.) as well as the ethylacetate (10-50 mg/kg, i.p.), butanol and aqueous fractions (5-50 mg/kg, i.p.) of the extract were examined. Sedation was assessed as reduced novelty-induced rearing (NIR), reduced spontaneous locomotor activity (SLA) and increased pentobarbitone-induced sleeping time (PIST) in mice. The anti-anxiety effect (methanol 2.5-5.0; butanol 5.0; aqueous 20.0; ethylacetate 25.0 mg/kg, i.p.) was assessed using an elevated plus maze. LD50 was calculated for the extract and the fractions after the intraperitoneal route of administration using the Locke method. The methanolic extract, the butanol and the aqueous fractions inhibited rearing and spontaneous locomotion but prolonged pentobarbitone induced sleep. The ethylacetate fraction however increased both rearing and locomotion and decreased pentobarbitone sleeping time. The butanol and aqueous fractions, but not the methanol extract showed indices of open arm avoidance consistent with anti-anxiety effect. Naltrexone (2.5 mg/kg, i.p.) reversed the inhibition of rearing, locomotion and prolongation of pentobarbitone sleep due to the aqueous fraction of the extract. Flumazenil (2mg/kg, i.p.) abolished the effects of both methanolic extract and the butanol fraction on rearing, locomotion, pentobarbitone sleep and anxiety model. The methanolic extract, the butanol and aqueous fractions possess sedative activity while the ethylacetate fraction possesses stimulant property. The anxiolytic effect was found in both the aqueous fraction and the butanol fraction but not in the main methanol extract and also not in the ethylacetate fraction. Flumazenil, blocked the effect of the leaves of Stachytarpheta cayennensis on rearing, locomotion and elevated plus maze suggesting that GABA receptors are involved in the observed sedative and anxiolytic activities. This study also found opioid receptors involved in the sedative activity of the leaves of Stachytarpheta cayennensis. The rationale for the ethnomedicinal use of the leaves for the management of insomnia and anxiety were confirmed scientifically in this study.

Bronchorelaxant property of 'African potato' (Hypoxis hemerocallidea corm) aqueous extract in vitro.

This study was undertaken to investigate the bronchorelaxant effect of Hypoxis hemerocallidea corm ('African potato') aqueous extract (APE) on spasmogen-provoked contractions of guinea-pig isolated tracheal smooth muscle preparations. APE (25-400 mg/ml) relaxed spasmogen (histamine-, carbachol- and potassium-)-induced contractions of the isolated tracheal muscle preparations in a concentration-dependent manner. The relaxant effects of APE on spasmogen-evoked contractions of the tracheal muscle preparations were not altered by bath-applied propranolol (0.1-5.0 microg/ml), which markedly inhibited or completely abolished the relaxant effects of isoprenaline (0.1-5.0 microg/ml). Although the precise mechanism of the bronchorelaxant effect of APE could not be established in the present study, it is unlikely that the herb's aqueous extract stimulates the beta(2)-adrenoceptors present on the bronchial smooth muscles to produce its bronchodilatation. The finding that APE significantly relaxed (P<0.05) histamine-, carbachol- and high potassium ion concentration (K(+), 80 mM)-induced contractions of guinea-pig isolated bronchial muscle preparations appears to suggest that the bronchospasmolytic effect of the plant's extract is probably not mediated through a specific receptor, but rather, probably mediated via a non-specific bronchospasmolytic mechanism.