Browsing by Author "Owolabi, Adegboyega Rotimi"

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    Ketamine Induced Analgesia in Mice at Sub-psychotomimetic Dose
    (West African Journal of Pharmacology and Drug Research, 2017-01) Atunwa, Soliu Abiola; Adeyemi, Oluwole Isaac; Owolabi, Adegboyega Rotimi
    The roles of N- Methyl –D- Aspartate receptor in the processing of nociception have led to renewed clinical interest in ketamine, an antagonist of the NMDA receptor. Low-dose ketamine had been reported to possess an analgesic effect though the paucity and inconsistency of such data have called for direct evaluation of this claim. This study, therefore, explored the analgesic effect of a sub-psychotomimetic dose of ketamine (SPDK), evaluated such effect on morphine- and diclofenac-induced analgesia, and determined its possible neuronal mechanism of analgesia. Mice weighing between 18-25 g were randomly distributed into two major groups consisting of Group 1 and 2 which were used for the assessment of analgesic effect and determination of the neuronal mechanism of 1 mg/kg ketamine using the hot plate model; and the formalin-induced pain model respectively. Data were presented as mean ± standard error of mean SEM and analyzed using ANOVA followed by post-hoc analysis (Student-Newman-Keuls) and P < 0.05 was set as an acceptable level of significance. The SPDK induced significant analgesia in the hot plate model but caused allodynia in the formalin-induced pain model. In addition, SPDK potentiated morphine-induced and diclofenac-induced analgesia in both the hot plate and formalin tests, while naloxone significantly blocked its analgesic effect at 90 minutes post-administration in the hot plate test. This study showed that SPDK induced analgesia in the acute pain model but aggravated pain in the chronic model. It also potentiated both morphine and diclofenac-induced analgesia possibly mediated through modulation of opioidergic pathway in mice. Keywords: Sub-Psychotomimetic Dose, Ketamine, morphine, diclofenac, allodynia, hot plate model, formalin-induced pain model, NMDA receptors, opioidergic pathway
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    Neurobehavioural Effects of Acute and Repeated Administrations of Sub-Psychotomimetic Dose of Ketamine in Mice
    (Ife Journal of Science and Technology, 2019) Atunwa, Soliu; Adeyemi, Oluwole; Owolabi, Adegboyega Rotimi
    Recent studies have shown that sub-anaesthetic doses of ketamine may induce analgesia, but its psychotomimetic side effects have called for caution. This study therefore, explored a possible sub-psychotomimetic dose of ketamine (SPDK) and determined the influence of frequency of exposure on its neurobehavioural effects in mice. Mice of either sex weighing 18 - 25 g were randomly selected into three major groups: A, B, and C. Group A was distributed into seven sub-groups (n=12) and treated with saline (10 μL/g/body weight); 1, 2, 4, 6, 8, and 10 mg/kg ketamine for stereotyped horizontal locomotion (SHL) assessment using the open field test. Groups B and C were each allotted into three sub-groups (n=7): I, II, and III. They were treated with saline (10 μL/g/body weight) as negative control, 1 mg/kg ketamine and 1.5 mg/kg scopolamine as positive control; and assessed for neurobehavioural effects of acute and repeated administrations using elevated plus-maze (EPM) and Y-maze respectively. Data were presented as Mean ± SEM and analyzed using ANOVA followed by Student-Newman-Keuls test with p < 0.05. The results showed that 1 mg/kg ketamine is devoid of psychotomimetic side effects (1.979, p > 0.05), whereas, ketamine 2, 4, 6, 8 and 10 mg/kg induced significant increase (8.258, p < 0.001), (7.688, p < 0.001), (7.916, p < 0.001), (10.580, p < 0.001) and (13.244, p < 0.001) respectively in SHL compared with the saline group in the open field paradigm. Therefore, ketamine 1 mg/kg was chosen as the sub-psychotomimetic dose. Acute administration of SPDK did not significantly impair memory of mice in both EPM (6.751, p < 0.001) and Y-maze models (3.467, p < 0.05), whereas, its repeated administrations showed comparable results to the group administered scopolamine in both EPM (0.1460, p > 0.8654) and Y-maze models (1.258, p > 0.3126). This study concluded that 1 mg/kg of ketamine may be a sub-psychotomimetic dose; and ketamine-induced psychotomimetic side effects and cognitive impairments could be dose and time-dependent respectively. Keywords: Neurobehavioural effects; sub-psychotomimetic dose of ketamine; drug re-positioning; stereotyped horizontal locomotion; scopolamine