Morinda citrifolia L. commonly known as noni or Indian mulberry belongs to the family Rubiaceae. Noni fruit juice has recently become a very popular remedy for the treatment of several diseases, including psychiatric disorders. This study aimed to investigate the anticraving effect of Tahitian Noni® Juice (TNJ) against ethanol seeking behavior in ICR male mice using the conditioned place preference (CPP) test. The CPP procedure consisted of four phases: preconditioning, conditioning, extinction, and reinstatement. During conditioning, intraperitoneal (i.p.) injections of ethanol (2 g/kg body weight (bw)) and normal saline (10 ml/kg bw) were given on alternate days for 12 days. Then, the animals were subjected to extinction trials for the next 12 days to weaken CPP. Finally, CPP was reinstated in the extinguished animals by a single low-dose priming injection of ethanol (0.4 g/kg bw, i.p.). The effect of TNJ (as a source of drinking water) on different phases of ethanol CPP in mice was studied. TNJ-treated mice showed a significant reduction in ethanol seeking behavior in the CPP test. The reference drug, acamprosate (ACAM) also showed a similar effect in the CPP test. The outcome of this study suggests that TNJ is effective in attenuating ethanol craving in mice and could be utilized for the treatment of alcohol dependence. Further clinical studies in this direction are warranted to support the present preclinical findings.
The present study was designed to investigate the effect of a methanolic extract of Morinda citrifolia Linn. fruit (MMC) on the rewarding effect of heroin in the rat conditioned place preference (CPP) paradigm and naloxone-precipitated withdrawal in mice. In the first experiment, following a baseline preference test (preconditioning score), the rats were subjected to conditioning trials with five counterbalanced escalating doses of heroin versus saline followed by a preference test conducted under drug-free conditions (post-conditioning score) using the CPP test. Meanwhile, in the second experiment, withdrawal jumping was precipitated by naloxone administration after heroin dependence was induced by escalating doses for 6 days (3×/ day). The CPP test results revealed that acute administration of MMC (1, 3, and 5 g/kg body weight (bw), p.o.), 1 h prior to the CPP test on the 12th day significantly reversed the heroin-seeking behavior in a dose-dependent manner, which was similar to the results observed with a reference drug, methadone (3 mg/kg bw, p.o.). On the other hand, MMC (0.5, 1, and 3 g/kg bw, p.o.) did not attenuate the heroin withdrawal jumps precipitated by naloxone. These findings suggest that the mechanism by which MMC inhibits the rewarding effect of heroin is distinct from naloxone-precipitated heroin withdrawal.
The chick embryo chorioallantoic membrane (CAM) is a preclinical model widely used for vascular and anti-vascular effects of therapeutic agents in vivo. In this study, we examine the suitability of CAM as a predictive model for acute toxicology studies of drugs by comparing it to conventional mouse and rat models for 10 FDA-approved anticancer drugs (paclitaxel, carmustine, camptothecin, cyclophosphamide, vincristine, cisplatin, aloin, mitomycin C, actinomycin-D, melphalan). Suitable formulations for intravenous administration were determined before the average of median lethal dose (LD50) and median survival dose (SD(50)) in the CAM were measured and calculated for these drugs. The resultant ideal LD(50) values were correlated to those reported in the literature using Pearson's correlation test for both intravenous and intraperitoneal routes of injection in rodents. Our results showed moderate correlations (r(2)=0.42 - 0.68, P<0.005-0.05) between the ideal LD(50) values obtained using the CAM model with LD(50) values from mice and rats models for both intravenous and intraperitoneal administrations, suggesting that the chick embryo may be a suitable alternative model for acute drug toxicity screening before embarking on full toxicological investigations in rodents in development of anticancer drugs.
The interaction of pinostrobin (PS), a multitherapeutic agent with serum albumins of various mammalian species namely, goat, bovine, human, porcine, rabbit, sheep and dog was investigated using fluorescence quench titration and competitive drug displacement experiments. Analysis of the intrinsic fluorescence quenching data revealed values of the association constant, K(a) in the range of 1.49 - 6.12 × 10(4) M(-1), with 1:1 binding stoichiometry. Based on the PS-albumin binding characteristics, these albumins were grouped into two classes. Ligand displacement studies using warfarin as the site I marker ligand correlated well with the binding data. Albumins from goat and bovine were found to be closely similar to human albumin on the basis of PS binding characteristics.
Exposure to organophosphate insecticides such as fenitrothion (FNT) in agriculture and public health has been reported to affect sperm quality. Antioxidants may have a potential to reduce spermatotoxic effects induced by organophosphate. The present study was carried out to evaluate the effects of palm oil tocotrienol-rich fraction (TRF) in reducing the detrimental effects occurring in spermatozoa of FNT-treated rats. Adult male Sprague-Dawley rats were divided into four equal groups: a control group and groups of rats treated orally with palm oil TRF (200 mg/kg), FNT (20 mg/kg) and palm oil TRF (200 mg/kg) combined with FNT (20 mg/kg). The sperm characteristics, DNA damage, superoxide dismutase (SOD) activity, and levels of reduced glutathione (GSH), malondialdehyde (MDA), and protein carbonyl (PC) were evaluated. Supplementation with TRF attenuated the detrimental effects of FNT by significantly increasing the sperm counts, motility, and viability and decreased the abnormal sperm morphology. The SOD activity and GSH level were significantly increased, whereas the MDA and PC levels were significantly decreased in the TRF+FNT group compared with the rats receiving FNT alone. TRF significantly decreased the DNA damage in the sperm of FNT-treated rats. A significant correlation between abnormal sperm morphology and DNA damage was found in all groups. TRF showed the potential to reduce the detrimental effects occurring in spermatozoa of FNT-treated rats.
We studied the effects of Eurycoma longifolia Jack, commonly known as Tongkat Ali in Malaysia, on the initiation of sexual performance and the weights of sexual accessories in inexperienced castrated male rats. The doses of 200, 400 and 800 mg/kg body weight, which were extracted from E. longifolia Jack, were orally administered to the rats twice daily for 10 days prior to the tests and continued throughout the test period. Testosterone was used as a positive control after injecting 15 mg/kg daily subcutaneously for 32 days. Results showed that E. longifolia Jack produced a dose-dependent increase in sexual performance of the treated animals, but the E. longifolia Jack groups showed lower sexual performance in mounting, intromission and ejaculation than the testosterone group. Further results also showed that E. longifolia Jack promoted the growth of both ventral prostate and seminal vesicles as compared with the control, but the growth of sexual accessories at 800 mg/kg of butanol, methanol, water and chloroform fractions of E. longifolia Jack was less than that of testosterone treated group. The present study therefore gives further evidence of the folkuse of E. longifolia as an aphrodisiac.
The effects of Eurycoma longifolia Jack were studied on the libido of sexually experienced male rats after dosing them with 200, 400 and 800 mg/kg body weight twice daily of different fractions of E. longifolia Jack for 10 days. Results showed that E. longifolia Jack produced a dose-dependent increase in mounting frequency of the treated animals with 400 mg/kg of chloroform, methanol, water and butanol fractions resulting in mounting frequencies of 5.3 +/- 1.2, 4.9 +/- 0.7, 4.8 +/- 0.7 and 5.2 +/- 0.1, and 800 mg/kg further increased them to 5.4 +/- 0.8, 5.4 +/- 0.8, 5.2 +/- 0.6 and 5.3 +/- 0.2 respectively but there were no erections, intromissions, ejaculations or seminal emissions during the 20-min observation period which allowed for the measurement of sexual arousal reflected by mounting frequency uninfluenced by other behavioural components. This study provides evidence that E. longifolia Jack is a potent stimulator of sexual arousal in sexually vigorous male rats in the absence of feedback from genital sensation.
In an earlier report, we demonstrated an antipsychotic-like activity of a methanolic extract of Morinda citrifolia Linn fruit in mouse models and postulated the contribution of its bioactive principles, scopoletin and rutin. Moreover, the antidopaminergic activities of scopoletin and rutin were reported in isolated vas deferens preparations. In the present study, scopoletin and rutin were assessed for antipsychotic-like activity using apomorphine-induced climbing behavior and methamphetamine-induced stereotypy in mice. The results of this study revealed that scopoletin and rutin (0.05, 0.1, 0.5, and 1 mg/kg, p.o.) had a "U-shaped" dose-dependent effect on climbing and stereotyped behaviors induced by apomorphine and methamphetamine, respectively, in mice. A significant reduction in climbing and stereotyped behaviors caused by scopoletin and rutin was observed only at a dose 0.1 mg/kg. This study suggests that scopoletin and rutin can alleviate positive symptoms of schizophrenia only at a specific dose. Further studies evaluating the effects of scopoletin and rutin on animal models for negative symptoms of schizophrenia are required for a novel drug discovery in the treatment of neuropsychiatric diseases.
In earlier ex vivo studies, we reported the biphasic effect of a methanolic extract of unripe Morinda citrifolia fruit (MMC) on dopamine-induced contractility in isolated rat vas deferens preparations. The present in vivo study was designed and undertaken to further explore our earlier ex vivo findings. This study examined the effect of the ethyl acetate fraction of a methanolic extract of unripe Morinda citrifolia Linn. fruit (EA-MMC; 5-100 mg/kg, p.o.) on the dopaminergic system using mouse models of apomorphine-induced climbing time and climbing behavior, methamphetamine-induced stereotypy (sniffing, biting, gnawing, and licking) and haloperidol-induced catalepsy using the bar test. Acute treatment with EA-MMC at a low dose (25 mg/kg, p.o.) significantly attenuated the apomorphine-induced climbing time and climbing behavior in mice. Similarly, EA-MMC (5 and 10 mg/kg, p.o.) significantly inhibited methamphetamine-induced stereotyped behavior in mice. These results demonstrated that the antidopaminergic effect of EA-MMC was observed at relatively lower doses (<25 mg/kg, p.o.). On the other hand, EA-MMC showed dopaminergic agonistic activity at a high dose (3,000 mg/kg, p.o.), which was evident from alleviation of haloperidol (a dopamine D2 blocker)-induced catalepsy in mice. Therefore, it is concluded that EA-MMC might possess a biphasic effect on the dopaminergic system, i.e., an antagonistic effect at lower doses (<25 mg/kg, p.o.) and an agonistic effect at higher doses (>1,000 mg/kg, p.o.). However, further receptor-ligand binding assays are necessary to confirm the biphasic effects of M. citrifolia fruit on the dopaminergic system.
Chronic stress has been associated with impairment of memory, learning, and social cognition. In animal studies, chronic stress has been shown to impair rodent sociability behaviour which mimics social withdrawal as observed in depression patients. The effect of chronic stress on social recognition, however, is uncertain. Moreover, with reference to spatial learning and memory, the effect of chronic stress is dependent on the type of behavioural task: an appetitively or aversively motivated tasks. The effect of chronic stress was consistent in impairing spatial learning and memory in the appetitive task; however, the effect was inconsistent in an aversive task like the Morris water maze. Thus, we aimed to investigate the effect of chronic restraint stress on sociability and social recognition by using a modified protocol of the three-chamber paradigm and the effect of chronic restraint stress on spatial learning and memory by using the Morris water maze test in young adult C57BL/6J male mice. The present report also describes a modified protocol of the three-chamber paradigm. Our modification is based on measurement of sniffing behaviour, which is a direct social interaction that represents sociability. We used the chronic restraint stress paradigm for 6 h/day for 21 days to induce depression-like symptoms in male C57BL/6J mice which were validated by forced-swim test. We observed that the stressed group had impairments in their sociability behaviour but that social recognition was not affected. Furthermore, we confirmed that chronic stress produced no significant impairment in spatial learning and memory of the mice in the water maze.
Phencyclidine (PCP) has been used to model cognitive deficits related to schizophrenia in rats and mice. However, the model in mice is not consistent in terms of the PCP effective dose reported. Furthermore, most of the previous studies in mice excluded the presence of drug washout period in the regime. Thus, we aimed to optimize the dose of PCP in producing robust cognitive deficits by implementing it in a PCP regime which incorporates a drug washout period. The regimen used was 7 days' daily injection of PCP or saline for treatment and vehicle groups, respectively; followed by 24 h drug washout period. After the washout period, the test mice were tested in water maze (5 days of acquisition + 1 day of probe trial) for assessment of spatial learning and memory. Initially, we investigated the effect of PCP at 2mg/kg, however, no apparent impairment in spatial learning and memory was observed. Subsequently, we examined the effect of higher doses of PCP at 5, 10 and 20 mg/kg. We found that the PCP at 10 mg/kg produced a significant increase in "latency to reach the platform" during the acquisition days and a significant increase in "latency of first entry to previous platform" during the probe day. There was no significant change observed in "swim speed" during the test days. Thus, we concluded that PCP at 10 mg/kg produced robust deficits in spatial learning and memory without being confounded by motor disturbances.
People consume Catha edulis (khat) for its euphoric effect, and type 1 diabetics have claimed that khat could reduce elevated levels of blood sugar. However, khat has been suggested to provoke diabetes mellitus through destruction of pancreatic β-cells. This study investigated the effect of an ethanolic khat extract on pancreatic functions in type 1 diabetes (T1DM)-induced male Sprague-Dawley rats and to assess its in vitro cytotoxicity in rat pancreatic β-cells (RIN-14B). T1DM was induced in a total of 20 rats with a single intraperitoneal injection of 75 mg/kg of streptozotocin. The rats were distributed into four groups (n=5): the diabetic control, 8 IU insulin-treated, 200 mg/kg khat-treated, and 400 mg/kg khat-treated groups. Another 5 rats were included as a nondiabetic control. Body weight, fasting blood sugar, and caloric intake were recorded weekly. Four weeks after treatment, the rats were sacrificed, and blood was collected for insulin, lipid profile, total protein, amylase, and lipase analysis, while pancreases were harvested for histopathology. In vitro, khat exerted moderate cytotoxicity against RIN-14B cells after 24 and 48 h but demonstrated greater inhibition against RIN-14B cells after 72 h. Neither 200 mg/kg nor 400 mg/kg of khat produced any significant reduction in blood sugar; however, 200 mg/kg khat extract provoked more destruction of pancreatic β-cells as compared with the diabetic control. Ultimately, neither 200 mg/kg nor 400 mg/kg of khat extract could produce a hypoglycemic effect in T1DM-induced rats. However, 200 mg/kg of khat caused greater destruction of pancreatic β-cells, implying that khat may cause a direct cytotoxic effect on pancreatic β-cells in vitro.
Metabolic syndrome is a cluster including hyperglycaemia, obesity, hypertension, and hypertriglyceridaemia as a result of biochemical and physiological alterations and can increase the risk of cardiovascular disease and diabetes. Fundamental research on this disease requires validated animal models. One potential animal model that is rapidly gaining in popularity is zebrafish (Danio rerio). The use of zebrafish as an animal model conveys several advantages, including high human genetic homology, transparent embryos and larvae that allow easier visualization. This review discusses how zebrafish models contribute to the development of metabolic syndrome studies. Different diseases in the cluster of metabolic syndrome, such as hyperglycaemia, obesity, diabetes, and hypertriglyceridaemia, have been successfully studied using zebrafish; and the model is promising for hypertension and cardiovascular metabolic-related diseases due to its genetic similarity to mammals. Genetic mutation, chemical induction, and dietary alteration are among the tools used to improve zebrafish models. This field is expanding, and thus, more effective and efficient techniques are currently developed to fulfil the increasing demand for thorough investigations.
Dietary antioxidant supplements such as L-glutathione have gained considerable attention in dermatology and cosmeceutical fields. L-glutathione possesses antiaging, antimelanogenic, antioxidant, and anticancer properties. This study aimed to investigate the inhibitory effects of L-glutathione on melanogenesis activity and oxidative stress in ultraviolet B (UVB)-irradiated BALB/c mice. Eighteen female BALB/c mice were randomly divided into 3 groups: a control group (n=6), a group without UVB irradiation and L-glutathione administration; a UVB irradiated group (n=6), a group irradiated with a UVB dose of 250 mJ/cm2 for 3 min; and a treatment group (n=6), a group irradiated with UVB and treated with 100 mg/kg of L-glutathione by oral gavage. Treatment was given for 14 days, and UVB irradiation was given on days 9, 11, and 13. Oral L-glutathione significantly (P<0.05) reduced lipid peroxidation and elevated superoxide dismutase activity the and glutathione level. L-glutathione also inhibited melanin content and tyrosinase activity significantly (P<0.05) as compared with the UVB-irradiated group. Histopathological examination also showed that L-glutathione reduced the deposition of melanin pigment in the basal layer of the epidermis as compared with that in UVB-irradiated mice. All in all, the present study demonstrated that L-glutathione has the potential to be developed as a photoprotection agent against UVB-induced oxidative stress and melanogenesis.