Displaying publications 341 - 360 of 426 in total

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  1. Koriem KM, Abdelhamid AZ, Younes HF
    Toxicol. Mech. Methods, 2013 Feb;23(2):134-43.
    PMID: 22992185 DOI: 10.3109/15376516.2012.730561
    Caffeic acid (CA) (3,4-dihydroxycinnamic acid) is among the major hydroxycinnamic acids. Hydroxycinnamic acid is the major subgroup of phenolic compounds. Methamphetamine (METH) is a potent addictive psychostimulant. Chronic use and acute METH intoxication can cause substantial medical consequences, including spleen, kidney, liver and heart. The objective of the present study was to evaluate the antioxidant activity of CA to protect against oxidative stress and DNA damage to various organs in METH toxicity. Thirty-two male Sprague Dawley (SD) rats were divided into four equal groups: group 1 was injected (i.p) with saline (1 mL/kg) while groups 2,3 and 4 were injected (i.p) with METH (10 mg/kg) twice a day over five days period. Where 100 & 200 mg/kg of CA were injected (i.p) into groups 3 and 4, respectively one day before exposure to METH injections. Tissue antioxidants and DNA content were evaluated in different tissues. METH decreased glutathione (GSH) and glutathione peroxidase (GPx) levels while increased malondialdehyde (MDA), catalase (CAT) and protein carbonyl levels in brain (hypothalamus), liver, and kidney tissues of rats. METH increased hyperdiploidy in these tissues and DNA damage results. Prior treatment of CA to animals exposed to METH restores the above parameters to the normal levels and preserves the DNA content of these tissues. These results were supported by histopathological investigations. In conclusion, METH induced oxidative stress and DNA damage and pretreatment of CA before METH injections prevented tissue oxidative stress and DNA damage in METH-treated animals.
    Matched MeSH terms: Central Nervous System Stimulants/toxicity*
  2. Hashim P, Sidek H, Helan MH, Sabery A, Palanisamy UD, Ilham M
    Molecules, 2011;16(2):1310-22.
    PMID: 21278681 DOI: 10.3390/molecules16021310
    Leaves of Centella asiatica (Centella) were analysed for their triterpene composition and bioactivity such as collagen enhancement, antioxidant, anticellulite and UV protection capacity properties. Triterpenes of Centella were measured using HPLC-PAD on an Excil ODS 5 mm (C18) column for the simultaneous determination of asiatic acid, madecassic acid, asiaticoside and madecassoside. Centella was found to contain significant amounts of madecassoside (3.10 ± 4.58 mg/mL) and asiaticoside (1.97 ± 2.65 mg/mL), but was low in asiatic and madecassic acid. The highest collagen synthesis was found at 50 mg/mL of Centella extracts. The antioxidant activity of Centella (84%) was compared to grape seed extract (83%) and Vitamin C (88%). Its lipolytic activity was observed by the release of glycerol (115.9 µmol/L) at 0.02% concentration. Centella extracts exhibited similar UV protection effect to OMC at 10% concentration. In view of these results, the potential application of Centella in food and pharmaceutical industries is now widely open.
    Matched MeSH terms: Central Nervous System Stimulants/pharmacology
  3. Abdulla MH, Sattar MA, Abdullah NA, Khan AH, Anand Swarup KR, Rathore HA, et al.
    Ups. J. Med. Sci., 2011 Mar;116(1):18-25.
    PMID: 21047287 DOI: 10.3109/03009734.2010.526723
    This study examined the effect of renal sympathetic innervation on adrenergically and angiotensin II (Ang II)-induced renal vasoconstriction in Wistar-Kyoto (WKY) rats.
    Matched MeSH terms: Sympathetic Nervous System/physiology*
  4. Islam MN, Jesmine K, Kong Sn Molh A, Hasnan J
    Leg Med (Tokyo), 2009 Apr;11 Suppl 1:S147-50.
    PMID: 19345131 DOI: 10.1016/j.legalmed.2009.02.035
    A small amount of Methamphetamine (MA) can produce behavioural changes such as euphoria, increased alertness, paranoia, decreased appetite and increased physical activity. In cardiovascular system, it can produce chest pain and hypertension which can result in cardiovascular collapse. In addition, MA causes accelerated heartbeat, elevated blood pressure. It can also cause irreversible damage to blood vessels in the brain. A number of sympathomimetic amines are capable of causing myocardial damage, but the cardio-toxic action of MA has been of particular interest since standardized dosage consistently produces myocardial lesions. As this drug is a choice of many teenagers and young adults, the damage to their health, as well as their future aspects could be greatly affected, therefore more evidence must be sought to convince them the negative root and show them the optimism of recovery and salvation. To clarify the effect of Methamphetamine (MA) on myocardium, 56 male Wister rats aged four weeks were divided equally into MA, Methamphetamine withdrawal (MW), Placebo (P) and Control (C) group were examined following daily intra-peritoneal administration of MA at a dose of 5 mg/kg body weight for 2, 4, 8 and 12 weeks. Normal saline was similarly injected in P group. Light microscopic changes was seen in the myocardium of MA treated group including eosinophilic degeneration, atrophy, hypertrophy, disarray, edema, cellular infiltration, myolysis, granulation tissue, fibrosis and vacuolization. On the other hand, the withdrawal group showed evidence of gradual recovery of those myocardial changes. Optimism is therefore generated about possibility of returning towards normal by withdrawing of this drug by the addicts.
    Matched MeSH terms: Central Nervous System Stimulants/toxicity*
  5. Yashodhara BM, Umakanth S, Pappachan JM, Bhat SK, Kamath R, Choo BH
    Postgrad Med J, 2009 Feb;85(1000):84-90.
    PMID: 19329703 DOI: 10.1136/pgmj.2008.073338
    Omega-3 fatty acids (omega-3 FAs) are essential fatty acids with diverse biological effects in human health and disease. Reduced cardiovascular morbidity and mortality is a well-established benefit of their intake. Dietary supplementation may also benefit patients with dyslipidaemia, atherosclerosis, hypertension, diabetes mellitus, metabolic syndrome, obesity, inflammatory diseases, neurological/ neuropsychiatric disorders and eye diseases. Consumption of omega-3 FAs during pregnancy reduces the risk of premature birth and improves intellectual development of the fetus. Fish, fish oils and some vegetable oils are rich sources of omega-3 FAs. According to the UK Scientific Advisory Committee on Nutrition guidelines (2004), a healthy adult should consume a minimum of two portions of fish a week to obtain the health benefit. This review outlines the health implications, dietary sources, deficiency states and recommended allowances of omega-3 FAs in relation to human nutrition.
    Matched MeSH terms: Nervous System Diseases/prevention & control
  6. Maneesh M, Dutta S, Chakrabarti A, Vasudevan DM
    Indian J. Physiol. Pharmacol., 2006 Jul-Sep;50(3):291-6.
    PMID: 17193902
    Ethanol is a testicular toxin and it causes fertility abnormalities with low sperm count and impaired sperm motility in men. The present study was designed to investigate plasma testosterone level and hypothalamic pituitary gonadal (HPG) axis function in alcoholic men and also effect of ethanol on systemic oxidative stress. Forty six male alcohol abusers in the age group 20-40 years were selected. Fifty five, males in the same age group served as control. Alcohol abusers had significantly low plasma testosterone with low luteinizing hormone and follicle stimulating hormone. In addition they had significantly high thiobarbituric acid reactive substances (TBARS), superoxide dismutase and glutathione S-transferase, and low glutathione, ascorbic acid, catalase, glutathione reductase and glutathione peroxidase. Moreover, serum testosterone level in alcoholics negatively correlated with duration of alcohol abuse, and TBARS. Duration dependent decreased serum testosterone level in alcohol abusers might be due to 1) increased oxidative stress which can damage Leydig and supporting Sertoli cells and 2) impaired HPG axis.
    Matched MeSH terms: Central Nervous System Depressants/toxicity
  7. Hassan Z, Muzaimi M, Navaratnam V, Yusoff NH, Suhaimi FW, Vadivelu R, et al.
    Neurosci Biobehav Rev, 2013 Feb;37(2):138-51.
    PMID: 23206666 DOI: 10.1016/j.neubiorev.2012.11.012
    Kratom (or Ketum) is a psychoactive plant preparation used in Southeast Asia. It is derived from the plant Mitragyna speciosa Korth. Kratom as well as its main alkaloid, mitragynine, currently spreads around the world. Thus, addiction potential and adverse health consequences are becoming an important issue for health authorities. Here we reviewed the available evidence and identified future research needs. It was found that mitragynine and M. speciosa preparations are systematically consumed with rather well defined instrumentalization goals, e.g. to enhance tolerance for hard work or as a substitute in the self-treatment of opiate addiction. There is also evidence from experimental animal models supporting analgesic, muscle relaxant, anti-inflammatory as well as strong anorectic effects. In humans, regular consumption may escalate, lead to tolerance and may yield aversive withdrawal effects. Mitragynine and its derivatives actions in the central nervous system involve μ-opioid receptors, neuronal Ca²⁺ channels and descending monoaminergic projections. Altogether, available data currently suggest both, a therapeutic as well as an abuse potential.
    Matched MeSH terms: Central Nervous System/drug effects*
  8. Lee WS, Hafeez A, Hassan H, Raja NS, Puthucheary SD
    PMID: 16124437
    A retrospective review of patients with focal non-typhoidal Salmonella (NTS) infection was performed to determine its features and outcome. All patients with focal NTS infection admitted to the University of Malaya Medical Center, Malaysia, from 1993 to 2002 were studied. More than half (58%) of the 35 cases (54% male, median age 39 years, range 1.5 months to 79 years) were immunocompromized or had chronic medical conditions. One-third of the patients (34%) had superficial infections (lymphadenitis or subcutaneous tissue infection) and all recovered with antimicrobial therapy alone. Deep infections (66%) noted were: meningitis (9%), osteomyelitis or arthritis (26%), abscesses of the gastrointestinal tract or adjacent organs (20%), and others (11%). Deep infections were more likely to occur in the extremes of age (<6 months or >60 years, p< 0.04), associated with adverse outcomes with an overall mortality rate of 9%, or required major surgery (15%).
    Matched MeSH terms: Central Nervous System Infections/microbiology
  9. Mazlan M, Rajasegaran S, Engkasan JP, Nawawi O, Goh KJ, Freddy SJ
    Toxins (Basel), 2015 Sep;7(9):3758-70.
    PMID: 26402703 DOI: 10.3390/toxins7093758
    This study aims to determine the most efficacious dose of Botulinum neurotoxin type A (BoNT-A) in reducing sialorrhea in Asian adults with neurological diseases. A prospective, double-blind randomized controlled trial was conducted over 24 weeks. Thirty patients with significant sialorrhea were randomly assigned to receive a BoNT-A (Dysport(®)) injection into the submandibular and the parotid glands bilaterally via an ultrasound guidance. The total dose given per patient was either BoNT-A injection of (i) 50 U; (ii) 100 U; or (iii) 200 U. The primary outcome was the amount of saliva reduction, measured by the differential weight (wet versus dry) of intraoral dental gauze at baseline and at 2, 6, 12, and 24 weeks after injection. The secondary outcome was the subjective report of drooling using the Drooling Frequency and Severity Scale (DFS). Saliva reduction was observed in response to all BoNT-A doses in 17 patients who completed the assessments. Although no statistically significant difference among the doses was found, the measured reduction was greater in groups that received higher doses (100 U and 200 U). The group receiving 200 U of Dysport(®) showed the greatest reduction of saliva until 24 weeks and reported the most significant improvement in the DFS score.
    Matched MeSH terms: Nervous System Diseases/drug therapy*
  10. Mohamad A, Azlan A, Adon MY, Khoo HE, Razman MR
    Asia Pac J Clin Nutr, 2015;24(3):515-24.
    PMID: 26420195 DOI: 10.6133/apjcn.2015.24.3.06
    The aim of this study was to determine the level of exposure to polychlorinated biphenyls (PCBs) and selected heavy metals among fishermen via dietary intake of fish and other seafood from the eastern coast along the Straits of Malacca. This study determined the neurobehavioural performances (based on neurobehavioural core test battery scores) of the fishermen and evaluated the correlations between scores of neurobehavioural core test battery and exposure factors. Ninety fishermen participated in the study. The total fish intakes of the fishermen were measured using a set of food frequency questionnaires. The PCBs contents in the seafood samples ranged between 0.2 and 0.6 pg/g fresh sample. The concentrations of mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) in the seafood samples were 1.1-5.4, 0.3-4.4, 0.6-36.1, and 0.02-0.3 μg/g fresh sample, respectively. The PCBs, Hg, As, Cd, and Pb exposures of the fishermen was estimated to be 2.8, 0.02, 4.5, 0.09, and 0.5 pg/kg body weight/day, respectively. PCB and heavy metal exposures through dietary intake of fish and seafood were within the tolerable daily limits. The results of neurobehavioural core test battery revealed that the neurobehavioural performances of the fishermen were not affected due to PCB and heavy metal intoxication. No correlations were found between the exposure and neurobehavioural performance among the fishermen. These data are useful for policy makers to assure the safety and quality of seafood in relation to sea pollution. Although the levels of exposure were low, periodic assessment of the quality of fish and fish products is required due to the polluted seawater.
    Matched MeSH terms: Nervous System Diseases/epidemiology*
  11. Baba R, Razak M
    Med J Malaysia, 1998 Sep;53 Suppl A:42-51.
    PMID: 10968182
    Out of 218 fractures of humeral shaft treated in the department, 23 (10.5%) of them developed non-union. 14/23 (60.9%) fracture were located in middle third. Transverse (52.2%), short oblique (17.4%) and comminuted fracture (13.0%) constituted about 82% of all initial fracture pattern. Twelve cases (52.5%) were initially treated with hanging cast. Radial nerve palsy occurred in 4/23 (17.4%) of patient and all of them located at lower third of humerus and only one recovered after eight weeks of injury. Factors such as middle third comminuted opened fractures, soft tissue interposition, improper immobilization and poor patient compliance were found to be directly associated with the non-union. All non-unions healed following plating and bone grafting. Overall 17/23 patient (74%) had good results, 4/23 (17%) fair and 2/23 (9%) with poor functional results.
    Matched MeSH terms: Peripheral Nervous System Diseases/etiology
  12. Goh KJ, Tan CT, Chew NK, Tan PS, Kamarulzaman A, Sarji SA, et al.
    N Engl J Med, 2000 Apr 27;342(17):1229-35.
    PMID: 10781618 DOI: 10.1056/NEJM200004273421701
    BACKGROUND: Between September 1998 and June 1999, there was an outbreak of severe viral encephalitis due to Nipah virus, a newly discovered paramyxovirus, in Malaysia.
    METHODS: We studied the clinical features of the patients with Nipah virus encephalitis who were admitted to a medical center in Kuala Lumpur. The case definition was based on epidemiologic, clinical, cerebrospinal fluid, and neuroimaging findings.
    RESULTS: Ninety-four patients with Nipah virus infection were seen from February to June 1999 (mean age, 37 years; ratio of male patients to female patients, 4.5 to 1). Ninety-three percent had had direct contact with pigs, usually in the two weeks before the onset of illness, suggesting that there was direct viral transmission from pigs to humans and a short incubation period. The main presenting features were fever, headache, dizziness, and vomiting. Fifty-two patients (55 percent) had a reduced level of consciousness and prominent brain-stem dysfunction. Distinctive clinical signs included segmental myoclonus, areflexia and hypotonia, hypertension, and tachycardia and thus suggest the involvement of the brain stem and the upper cervical spinal cord. The initial cerebrospinal fluid findings were abnormal in 75 percent of patients. Antibodies against Hendra virus were detected in serum or cerebrospinal fluid in 76 percent of 83 patients tested. Thirty patients (32 percent) died after rapid deterioration in their condition. An abnormal doll's-eye reflex and tachycardia were factors associated with a poor prognosis. Death was probably due to severe brain-stem involvement. Neurologic relapse occurred after initially mild disease in three patients. Fifty patients (53 percent) recovered fully, and 14 (15 percent) had persistent neurologic deficits.
    CONCLUSIONS: Nipah virus causes a severe, rapidly progressive encephalitis with a high mortality rate and features that suggest involvement of the brain stem. The infection is associated with recent contact with pigs.
    Matched MeSH terms: Nervous System Diseases/etiology
  13. Razak MA, Fazir M
    Med J Malaysia, 2000 Sep;55 Suppl C:97-100.
    PMID: 11200052
    A rare case of an aggressive recurrent giant cell tumour of axis is presented. The problems encountered in diagnosis and management are discussed. High dose dexamethasone was found to be useful managing this inoperable aggressive tumour which was compressing the cord. Early diagnosis would facilitate wide excision of the tumour with good prognosis.
    Matched MeSH terms: Nervous System Diseases/etiology*
  14. Boo NY, Ong LC, Lye MS, Chandran V, Teoh SL, Zamratol S, et al.
    J Paediatr Child Health, 1996 Oct;32(5):439-44.
    PMID: 8933407
    OBJECTIVE: To compare the morbidities in the very low birthweight (VLBW; < 1500 g) and normal birthweight (NBW; > or = 2500 g) Malaysian infants during the first year of life.

    METHODOLOGY: Prospective observational cohort study of consecutive surviving VLBW infants and randomly sampled NBW infants born in the Kuala Lumpur Maternity Hospital between 1 December 1989 and 31 December 1992. Infants were followed up regularly during the first year of life, after correction for prematurity.

    RESULTS: Compared with NBW infants (n = 106), VLBW infants (n = 127) had significantly higher risk of failure to thrive (odds ratio [OR] = 8.0, 95% confidence intervals [CI]: 1.1 to 354.3), wheezing (OR = 3.7, 95% CI: 1.6 to 9.3), rehospitalization (OR = 2.3, 95% CI: 1.1 to 5.0), cerebral palsy (OR = 8.6, 95% CI: 2.0 to 77.6), neurosensory hearing loss (OR = 12.0, 95% CI: 1.7 to 513.6) and visual loss (7.9 vs 0%, P = 0.002). The mean mental developmental index (MDI) and mean psychomotor developmental index (PDI) at 1 year of age were significantly lower among VLBW infants (MDI 99 [SD = 28], PDI 89 [SD = 25]) than NBW infants (MDI 106 [SD = 18], PDI 101 [SD = 18]) (95% CI for difference between means being MDI: -14.1 to -1.7; and PDI: -17.6 to -6.0). Logistic regression analysis showed that among VLBW infants: (i) male sex, Malay ethnicity and bronchopulmonary dysplasia were significant risk factors associated with wheezing; (ii) longer duration of oxygen therapy during the neonatal period, seizures after the post-neonatal period and wheezing were significant risk factors associated with rehospitalization; and (iii) longer duration of oxygen therapy during the neonatal period was a significant risk factor associated with adverse neurodevelopmental outcome during the first year of life.

    CONCLUSIONS: Compared with NBW infants, VLBW Malaysian infants had significantly higher risks of physical and neuro-developmental morbidities.

    Matched MeSH terms: Central Nervous System Diseases/etiology
  15. Tan AK, Azman A, Hoe TS, Rohana T
    Med J Malaysia, 1994 Dec;49(4):409-11.
    PMID: 7674978
    A six-year-old boy, a known case of acute lymphoblastic leukaemia (ALL) on remission since 1991 presented with leukocoria and poor vision of the left eye for two days' duration. Examination revealed endophthalmitis in the left eye with raised intraocular pressure. Anterior chamber paracentesis with vitreous biopsy confirmed a diagnosis of ocular involvement. Further investigation revealed that he also had bone marrow and central nervous system relapse. Clinical manifestation and treatment modalities of ocular involvement in leukaemia are discussed.
    Matched MeSH terms: Central Nervous System/pathology
  16. Low PH, Mangat MS, Liew DNS, Wong ASH
    World Neurosurg, 2020 12;144:e710-e713.
    PMID: 32949798 DOI: 10.1016/j.wneu.2020.09.045
    BACKGROUND: The novel coronavirus disease 2019 (COVID-19) pandemic has set a huge challenge to the delivery of neurosurgical services, including the transfer of patients. We aimed to share our strategy in handling neurosurgical emergencies at a remote center in Borneo island. Our objectives included discussing the logistic and geographic challenges faced during the COVID-19 pandemic.

    METHODS: Miri General Hospital is a remote center in Sarawak, Malaysia, serving a population with difficult access to neurosurgical services. Two neurosurgeons were stationed here on a rotational basis every fortnight during the pandemic to handle neurosurgical cases. Patients were triaged depending on their urgent needs for surgery or transfer to a neurosurgical center and managed accordingly. All patients were screened for potential risk of contracting COVID-19 prior to the surgery. Based on this, the level of personal protective equipment required for the health care workers involved was determined.

    RESULTS: During the initial 6 weeks of the Movement Control Order in Malaysia, there were 50 urgent neurosurgical consultations. Twenty patients (40%) required emergency surgery or intervention. There were 9 vascular (45%), 5 trauma (25%), 4 tumor (20%), and 2 hydrocephalus cases (10%). Eighteen patients were operated at Miri General Hospital, among whom 17 (94.4%) survived. Ninety percent of anticipated transfers were avoided. None of the medical staff acquired COVID-19.

    CONCLUSIONS: This framework allowed timely intervention for neurosurgical emergencies (within a safe limit), minimized transfer, and enabled uninterrupted neurosurgical services at a remote center with difficult access to neurosurgical care during a pandemic.

    Matched MeSH terms: Central Nervous System Vascular Malformations/surgery
  17. Anandakrishnan P, Khoo TB
    BMJ Case Rep, 2018 May 30;2018.
    PMID: 29848532 DOI: 10.1136/bcr-2018-224496
    Cerebral demyelination and optic neuritis are often seen in children with acute disseminated encephalomyelitis following various infections and immunisations. An eight month old girl presented with a left axillary lymph node swelling and an erythematous lace-like rash over her cheeks and trunk. She then developed acute encephalopathy, bilateral nystagmus, right hemiparesis and left facial nerve palsy. Her electroencephalogram showed an encephalopathic process and visual evoked response study were grossly abnormal. Her MRI brain showed hyperintensities in the midbrain, pons and bilateral cerebellar peduncles. She was treated as postinfectious cerebral demyelination with intravenous antibiotics, methylprednisolone and immunoglobulin. Left axillary lymph node excision biopsy and GeneXpert test detected Mycobacterium tuberculosis complex that prompted initiation of antituberculous therapy. Her chest X-ray and cerebrospinal fluid examinations for tuberculosis were normal. She showed significant recovery after 2 weeks. This case illustrates a rare presentation of cerebral demyelination and bilateral optic neuritis following suppurative BCG lymphadenitis.
    Matched MeSH terms: Tuberculosis, Central Nervous System/chemically induced
  18. Paudel YN, Angelopoulou E, Semple B, Piperi C, Othman I, Shaikh MF
    ACS Chem Neurosci, 2020 02 19;11(4):485-500.
    PMID: 31972087 DOI: 10.1021/acschemneuro.9b00640
    Glycyrrhizin (glycyrrhizic acid), a bioactive triterpenoid saponin constituent of Glycyrrhiza glabra, is a traditional medicine possessing a plethora of pharmacological anti-inflammatory, antioxidant, antimicrobial, and antiaging properties. It is a known pharmacological inhibitor of high mobility group box 1 (HMGB1), a ubiquitous protein with proinflammatory cytokine-like activity. HMGB1 has been implicated in an array of inflammatory diseases when released extracellularly, mainly by activating intracellular signaling upon binding to the receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4). HMGB1 neutralization strategies have demonstrated disease-modifying outcomes in several preclinical models of neurological disorders. Herein, we reveal the potential neuroprotective effects of glycyrrhizin against several neurological disorders. Emerging findings demonstrate the therapeutic potential of glycyrrhizin against several HMGB1-mediated pathological conditions including traumatic brain injury, neuroinflammation and associated conditions, epileptic seizures, Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Glycyrrhizin's effects in neurological disorders are mainly attributed to the attenuation of neuronal damage by inhibiting HMGB1 expression and translocation as well as by downregulating the expression of inflammatory cytokines. A large number of preclinical findings supports the notion that glycyrrhizin might be a promising therapeutic alternative to overcome the shortcomings of the mainstream therapeutic strategies against neurological disorders, mainly by halting disease progression. However, future research is warranted for a deeper exploration of the precise underlying molecular mechanism as well as for clinical translation.
    Matched MeSH terms: Nervous System Diseases/drug therapy*
  19. Khan MA, Sattar MA, Abdullah NA, Johns EJ
    Acta Pharmacol Sin, 2008 Feb;29(2):193-203.
    PMID: 18215348 DOI: 10.1111/j.1745-7254.2008.00727.x
    This study examined whether alpha1B-adrenoceptors are involved in mediating adrenergically-induced renal vasoconstrictor responses in rats with pathophysiological and normal physiological states.
    Matched MeSH terms: Sympathetic Nervous System/physiology*
  20. Harun N, Hassan Z, Navaratnam V, Mansor SM, Shoaib M
    Psychopharmacology (Berl), 2015 Jul;232(13):2227-38.
    PMID: 25616583 DOI: 10.1007/s00213-015-3866-5
    RATIONALE: Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction.

    OBJECTIVES: The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats.

    METHODS: Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement.

    RESULTS: Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus.

    CONCLUSION: The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

    Matched MeSH terms: Central Nervous System Stimulants/pharmacology
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