Sains Malaysiana 52(3)(2023): 837-850

http://doi.org/10.17576/jsm-2023-5203-12

Neuroprotective Effects of Ocimum basilicum L. var. thyrsiflora on Scopolamine-Induced Non-Spatial Memory Deficits in Rats

(Kesan Neuropelindung Ocimum basilicum L. var. thyrsiflora pada Kemerosotan Ingatan Bukan Reruang Aruhan Skopolamina Tikus)

NOR SYAFINAZ YAAKOB¹, MOHAMED ALI SEYED², MANALI HANITI MOHD-ZAHID³, HENG-HUI TEE¹, SHU-YUN YAP¹, SEK-WEN HO¹, YUSOF KAMISAH⁴ & NORAZRINA AZMI^1,*

¹Centre for Drug and Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Kuala Lumpur, Federal Territory, Malaysia

²Department of Biochemistry, Faculty of Science, University of Tabuk, Tabuk 71491, Kingdom of Saudi Arabia

³Department of Chemical Pathology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Darul Naim, Malaysia

⁴Department of Pharmacology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Kuala Lumpur, Federal Territory, Malaysia

Received: 13 October 2022/Accepted: 10 February 2023

Abstract

Pharmacological studies indicated that Ocimum basilicum L. var. thyrsiflora has numerous therapeutic potentials. The aim of this study was to investigate the neuroprotective action of O. basilicum leaf extract against scopolamine-induced non-spatial memory deficits in rats and to determine the changes in mRNA expressions of genes implicated in cognition and neuroprotection. O. basilicum leaves were extracted with 80% ethanol and verified for the presence of rosmarinic acid using high performance liquid chromatography method. Male Wistar rats were treated orally with either O. basilicum or the positive control piracetam for 14 days prior to the injection of 0.5 mg/kg scopolamine on the day of the novel object discrimination (NOD) test. Hippocampi were collected at the end of the test. mRNA expression of nicotinic acetylcholine α7 subunit (NA7), muscarinic M1 receptor (M1), neuronal nitric oxide synthase (nNOS), and 5-hydroxytryptamine receptor 3A (HTR3A) genes in the hippocampi were analyzed using qPCR method. The presence of rosmarinic acid in the plant extract was detected at chromatogram peak of Rt=16.891. NOD test results indicated that the lower dose of O. basilicum (200 mg/kg) significantly (p<0.05) reversed scopolamine-induced memory deficits in rats similar to the effects of piracetam. In addition, O. basilicum at the same dose alleviated the increase in mRNA expressions of the NA7, M1, nNOS, and HTR3A genes induced by scopolamine. The present findings suggest that O. basilicum is potentially neuroprotective in preventing memory impairment through alleviation of scopolamine-induced changes in hippocampal mRNA expression implicated in cognition and neuroprotection.

Keywords:  Cognition; gene expression; memory; neuroprotection; Ocimum basilicum

Abstrak

Kajian farmakologi menunjukkan bahawa Ocimum basilicum L. var. thyrsiflora mempunyai banyak potensi terapeutik. Matlamat kajian ini adalah untuk mengkaji kesan neuropelindung ekstrak daun O. basilicum terhadap kemerosotan ingatan bukan reruang aruhan skopolamina pada tikus dan untuk menentukan perubahan dalam ekspresi mRNA gen yang terlibat dalam kognisi dan perlindungan saraf. Daun O. basilicum telah diekstrak dengan 80% etanol dan kehadiran asid rosmarinik disahkan menggunakan kaedah kromatografi cecair berprestasi tinggi. Tikus Wistar jantan diberi O. basilicum atau piracetam sebagai kawalan positif secara oral selama 14 hari sebelum suntikan skopolamina 0.5 mg/kg diberikan pada hari ujian diskriminasi objek novel (NOD). Hipokampus dikumpul pada akhir ujian tersebut. Ekspresi mRNA subunit α7 nikotinik asetilkolin (NA7), reseptor M1 muskarinik (M1), nitrik oksida sintase neuron (nNOS), dan gen reseptor 5-hidroksitriptamina 3A (HTR3A) dalam hippokampus dianalisis menggunakan kaedah qPCR. Kehadiran asid rosmarinik dalam ekstrak tumbuhan dikesan pada puncak kromatogram Rt=16.891. Keputusan ujian NOD menunjukkan bahawa dos O. basilicum yang lebih rendah (200 mg/kg) memulihkan kemerosotan ingatan yang disebabkan oleh skopolamina dengan ketara (p<0.05) pada tikus serupa dengan kesan piracetam. Di samping itu, O. basilicum pada dos yang sama mengurangkan peningkatan dalam ekspresi mRNA gen NA7, M1, nNOS dan HTR3A yang diaruh oleh skopolamina. Hasil kajian ini menunjukkan bahawa O. basilicum mempunyai potensi neuropelindung dalam mencegah kemerosotan ingatan melalui pengurangan kesan yang disebabkan oleh skopolamina dalam ekspresi mRNA hipokampus yang terlibat dalam kognisi dan perlindungan saraf.

Kata kunci: Ekspresi gen; ingatan; kognisi; Ocimum basilicum; perlindungan saraf

REFERENCES

Al-Snafi, A.E. 2021a. Chemical constituents and pharmacological effects of Ocimum basilicum - A review. International Journal of Pharmaceutical Research 13(2): 2997-3013.

Al-Snafi, A.E. 2021b. Medicinal plants possessed beneficial therapeutic effects in Alzheimer’s disease and memory deficits. GSC Biological and Pharmaceutical Sciences 17(02): 008-033.

Azmi, N., Norman, C., Spicer, C.H. & Bennett, G.W. 2006. Effects of a neurotensin analogue (PD149163) and antagonist (SR142948A) on the scopolamine-induced deficits in a novel object discrimination task. Behavioural Pharmacology 17(4): 357-362.

Badiana, S.L.N., Ngah, E., Touo’yem, W.S.N., Sidiki, N., Bum, E.N. 2021. Ocimum basilicum L. (Lamiaceae) leaves aqueous extract improve learning and memory in the monosodium glutamate-induced neurotoxicity model of Alzheimer's disease through attenuating brain oxidative damage in experimental mice. GSC Biological and Pharmaceutical Sciences 17: 204-212.

Baritaux, O., Richard, H., Touche, J. & Derbesy, M. 1992. Effects of drying and storage of herbs and spices on the essential oil. Part I. Basil. Ocimum basilicum L. Flavour and Fragrances Journal 7(5): 267-271.

Barnes, J.M., Costall, B., Coughlan, J., Domeney, A.M., Gerrard, P.A., Kelly, M.E., Naylor, R.J., Onaivi, E.S., Tomkins, D.M. & Tyers, M.B. 1990. The effects of ondansetron, a 5-HT3 receptor antagonist, on cognition in rodents and primates.  Pharmacology Biochemistry and Behavior 35(4): 955-962.

Bartolini, L., Casamenti, F. & Pepeu, G. 1995. Aniracetam restores object recognition impaired by age, scopolamine, and nucleus basalis lesions. Pharmacology Biochemistry Behavior 53: 277-283.

Berić, T., Nikolić, B., Stanojević, J., Vuković-Gačić, B. & Knežević-Vukčević, J. 2008. Protective effect of basil (Ocimum basilicum L.) against oxidative DNA damage and mutagenesis. Food and Chemical Toxicology 46(2): 724-732.

Bertaina-Anglade, V.B., Enjaunes, E., Morillon, D. & Rochele, C.D. 2006. The object recognition test in rats and mice: A simple and rapid model in safety pharmacology to detect amnesic properties of a new chemical entity. Journal of Pharmacology and Toxicology Methods 54(2): 99-105. 

Besheer, J., Short, K.R. & Bevins, R.A. 2001. Dopaminergic and cholinergic antagonism in a novel-object detection task with rats. Behavior Brain Research 126: 211-217.

Bora, K.S., Arora, S. & Shri, R. 2011. Role of Ocimum basilicum L. in prevention of ischemia and reperfusion-induced cerebral damage, and motor dysfunctions in mice brain. Journal of Ethnopharmacology 137(3): 1360-1365.

Bradley, S.J., Bourgognon, J.M., Sanger, H.E., Verity, N., Mogg, A.J., White, D.J., Butcher, A.J., Moreno, J.A., Molloy, C., Macedo-Hatch, T., Edwards, J.M., Wess, J., Pawlak, R., Read, D.J., Sexton, P.M., Broad, L.M., Steinert, J.R., Mallucci, G.R., Christopoulos, A., Felder, C.C. & Tobin, A.B. 2017. M1 muscarinic allosteric modulators slow prion neurodegeneration and restore memory loss.  Journal of Clinical Investigation 127(2): 487-499.

Buhot, M.C., Martin, S. & Segu, L. 2000. Role of serotonin in memory impairment. Annals of Medicine 32(3): 210-221.

Carli, M., Luschi, R. & Samanin, R. 1997. Dose-related impairment of spatial learning by intrahippocampal scopolamine: Antagonism by ondansetron, a 5-HT₃ receptor antagonist.  Behavioural Brain Research 82(2): 185-194.

Cheng, Q. & Yakel, J.L. 2015. Activation of α7 nicotinic acetylcholine receptors increases intracellular cAMP levels via activation of AC1 in hippocampal neurons. Neuropharmacology 95: 405-414.

Cheng, Q. & Yakel, J.L. 2014. Presynaptic α7 nicotinic acetylcholine receptors enhance hippocampal mossy fiber glutamatergic transmission via PKA activation. Journal of Neuroscience 34(1): 124-133.

Chidamabaram, S.B., Pandian, A., Sekar, S., Haridass, S., Vijayan, R., Thiyagarajan, L.K., Ravindran, J., Rao, H., Raghavendran, B. & Kamarul, T. 2015. Sesame indicum, a nutritional supplement, elicits antiamnesic effect via cholinergic pathway in scopolamine intoxicated mice. Environmental Toxicology 31(12): 1955-1963.

Dennis, S.H., Pasqui, F., Colvin, E.M., Sanger, H., Mogg, A.J., Felder, C.C., Broad, L.M., Fitzjohn, S.M., Isaac, J.T.R. & Mellor, J.R. 2016. Activation of muscarinic M1 acetylcholine receptors induces long-term potentiation in the hippocampus.  Cerebral Cortex 26(1): 414-426.

Deutsch, J.A. 1971. The cholinergic synapse and the site of memory. Science 174: 788-794.

Dodart, J.C., Mathis, C. & Ungerer, A. 1997. Scopolamine-induced deficits in a two-trial object recognition task in mice. Neuroreports 8(5): 1173-1178.

Ennanceur, A. & Meliani, K. 1992a. Effects of physostigmine and scopolamine on rats’ performances in object-recognition and radial maze tests. Psychopharmacology (Berl). 109: 321-330.

Ennaceur, A. & Meliani, K. 1992b. A new one-trial test for neurobiological studies of memory in rats. III. Spatial vs non-spatial working memory. Behavior Brain Research 51: 83-92.

Ennanceur, A. & Delacour, J. 1988. A new one-trial test for neurobiological studies of memory in rats. Behavioral data. Behavior Brain Research 31(1): 47-59.

Fakhfouri, G., Rahimian, R., Dyhrfjeld-Johnsen, J., Zirak, M.R. & Beaulieu, J.M. 2019. 5-HT₃ receptor antagonists in neurologic and neuropsychiatric disorders: The iceberg still lies beneath the surface. Pharmacology Reviews 71(3): 383-412.  

Falsafi, S.K., Deli, A., Hoger, H., Pollak, A. & Lubec, G. 2012. Scopolamine administration modulates muscarinic, nicotinic and NMDA receptor systems. PLoS ONE 7(2): e32082.

Gee, V.J., Kracun, S., Cooper, S.T., Gibb, A.J. & Millar, N.S. 2007. Identification of domains influencing assembly and ion channel properties in alpha 7 nicotinic receptor and 5-HT3 receptor subunit chimaeras. British Journal of Pharmacology 152(4): 501-512.

Giridharan, V.V., Thandavarayan, R.A., Mani, V., Dundapa, T.A., Watanabe, K. & Konishi, T. 2011. Ocimum sanctum Linn. leaf extracts inhibit acetylcholinesterase and improve cognition in rats with experimentally induced dementia. Journal of Medicinal Food 14(9): 912-919.

Grayer, R.J., Kite, G.C., Goldstone, F.J., Bryan, S.E., Paton, A. & Putievsky, E. 1996. Infraspecific taxonomy and essential oil chemotypes in sweet basil, Ocimum basilicum. Phytochemistry 143: 1033-1039.

Haam, J. & Yakel, J.L. 2017. Cholinergic modulation of the hippocampal region and memory function. Journal of Neurochemistry 142: 111-121.

Harooni, H.E., Naghdi, N., Sepehri, H. & Rohani, A.H. 2009. The role of hippocampal nitric oxide (NO) on learning and immediate, short- and long-term memory retrieval in inhibitory avoidance task in male adult rats. Behavioural Brain Research 201(1): 166-172.

Harrell, A.V. & Allan, A.M. 2003. Improvements in hippocampal-dependent learning and decremental attention in 5-HT₃ receptor overexpressing mice. Learning & Memory 10(5): 410-419.

Hasanein, P. & Mahtaj, A.K. 2015. Ameliorative effect of rosmarinic acid on scopolamine-induced memory impairment in rats. Neuroscience Letters 585: 23-27.

Huang, M., Felix, A.R., Kwon, S., Lowe, D., Wallace, T., Santarelli, L. & Meltzer, H.Y. 2014. The alpha-7 nicotinic receptor partial agonist/5-HT3 antagonist RG3487 enhances cortical and hippocampal dopamine and acetylcholine release.  Psychopharmacology (Berl). 231(10): 2199-2210.

Jayasinghe, C.J., Gotoh, N., Aoki, T. & Wada, S. 2003. Phenolics composition and antioxidant activity of sweet basil (Ocimum basilicum L.). Journal of Agri and Food Chemistry 51(15): 4442-4449.

Joshi, H. & Parle, M. 2006. Evaluation of nootropic potential of Ocimum sanctum Linn. in mice. Indian Journal of Experimental Biology 44(2): 133-136.

Konar, A., Gupta, R., Shukla, R.K., Maloney, B., Khanna, V.K., Wadhwa, R., Lahiri, D.K. & Thakur M.K. 2019. M1 muscarinic receptor is a key target of neuroprotection, neuroregeneration and memory recovery by i-Extract from Withania somnifera.  Scientific Reports 9(1): 13990.

Koutroumanidou, E., Kimbaris, A., Kortsaris, A., Bezirtzoglou, E., Polissiou, M., Charalabopoulos, K. & Pagonopoulou, O. 2013. Increased seizure latency and decreased severity of pentylenetetrazol-induced seizures in mice after essential oil administration. Epilepsy Research and Treatment 2013: 532657.

Kumagai, Y., Kikushima, M., Nakai, Y., Shimojo, N. & Kunimoto, M. 2004. Neuronal nitric oxide synthase (NNOS) catalyzes one-electron reduction of 2,4,6-trinitrotoluene, resulting in decreased nitric oxide production and increased nNOS gene expression: Implication for oxidative stress. Free Radical Biology and Medicine 37(3): 350-357.

Kumar, N. & Kela, A.K. 2004. Ondansetron amelioration of scopolamine induced cognitive deficits in three-panel runway apparatus in rats. Indian Journal Experimental Biology 42(9): 919-921.

Kwon, S.H., Lee, H.K., Kim, J.A., Hong, S.I., Kim, H.C., Jo, T.H., Young, I.P., Chong, K.L., Yong, B.K., Seok, Y.L. & Choon, G.J. 2010. Neuroprotective effects of chlorogenic acid on scopolamine-induced amnesia via anti-acetylcholinesterase and anti-oxidative activities in mice. European Journal of Pharmacology 649(1-3): 210-217.

Levey, A.I. 1996. Muscarinic acetylcholine receptor expression in memory circuits: Implications for treatment of Alzheimer disease. Proceedings of the National Academy of Sciences 93(24): 13541-13546.

Lochner, M. & Thompson, A.J. 2016. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT₃ receptors. Neuropharmacology 108: 220-228.

Lu, C., Wang, Y., Xu, T., Li, Q., Wang, D., Zhang, L., Fan, B., Wang, F. & Liu, X. 2018. Genistein ameliorates scopolamine-induced amnesia in mice through the regulation of the cholinergic neurotransmission, antioxidant system and the ERK/CREB/BDNF signaling. Frontier Pharmacology 9: 1153.

Marisco, P.C., Carvalho, F.B., Rosa, M.M., Girardi, B.A., Gutierres, J.M., Jaques, J.A., Salla, A.P., Pimentel, V.C., Schetinger, M.R., Leal, D.B., Mello, C.F. & Rubin, M.A. 2013. Piracetam prevents scopolamine-induced memory impairment and decrease of NTPDase, 5’-nucleotidase and adenosine deaminase activities. Neurochemical Research 38(8): 1704-1714.

Mohamed, R.A., Abdallah, D.M., El-Brairy, A.I., Ahmed, K.A. & El-Abhar, H.S. 2021. Palonosetron/Methyllycaconitine deactivate hippocampal microglia 1, inflammasome assembly and pyroptosis to enhance cognition in a novel model of neuroinflammation. Molecules 26(16): 5068.

Mohd-Zahid, M.H., Jalil, J., Chan, K.M. & Azmi, N. 2018. Neuroprotective effects of Ocimum basilicum extract against hydrogen peroxide-induced oxidative stress in SK-N-SH neuroblastoma cells. Sains Malaysiana 47(9): 2129-2139.

Moura, A.C., Lazzari, V.M., Agnes, G., Almeida, S., Giovenardi, M. & Veiga, A.B. 2014. Transcriptional expression study in the central nervous system of rats: What gene should be used as internal control? Einstein (São Paulo) 12(3): 336-341.

Müller, W.E., Eckert, G.P. & Eckert, A. 1999. Piracetam: Novelty in a unique mode of action. Pharmacopsychology 32(1): 2-9.

Othman, M.S., Khaled, A.M., Al-Bagawi, A.H., Fareid, M.A., Ghany, R.A., Habotta, O.A. & Abdel Moneim, A.E. 2021. Hepatorenal protective efficacy of flavonoids from Ocimum basilicum extract in diabetic albino rats: A focus on hypoglycemic, antioxidant, anti-inflammatory and anti-apoptotic activities. Biomedicine and Pharmacotherapy 144: 112287.

Paul, V. & Ekambaram, P. 2011. Involvement of nitric oxide in learning and memory processes. Indian Journal of Medical Research 133(5): 471-478.

Pfaffl, M.W., Horgan, G.W. & Dempfle, L. 2002. Relative expression software tool (REST) for group-wise comparison and statistical analysis of relative expression results in real-time PCR. Nucleic Acids Research 30(9): e36.

Piller, N., Decosterd, I. & Suter, M.R. 2013. Reverse transcription quantitative real-time polymerase chain reaction reference genes in the spared nerve injury model of neuropathic pain: Validation and literature search. BMC Research Notes 6: 266.

Pitsikas, N., Rigamonti, A.E., Cella, S.G. & Muller, E.E. 2003. The 5-HT1A receptor antagonist WAY 100635 improves rats’ performance in different models of amnesia evaluated by the object recognition task. Brain Research 983: 215-222.

Rahman, W., Bauer, C.S., Bannister, K., Vonsy, J.L., Dolphin, A.C. & Dickenson, A.H. 2009. Descending serotonergic facilitation and the antinociceptive effects of pregabalin in a rat model of osteoarthritic pain. Molecular Pain 5: 45.

Ramakers, C., Ruijter, J.M., Deprez, R.H. & Moorman, A.F. 2003. Assumption-free analysis of quantitative real-time polymerase chain reaction (PCR) data. Neuroscience Letters 339(1): 62-66.

Rameshrad, M., Salehian, R., Fathiazad, F., Hamedeyazdan, S., Garjani, M. & Maleki-Dizaji, N. 2015. The effects of Ocimum basilicum ethanol extract on carrageenan induced paw inflammation in rats. Pharmaceutical Sciences 20(4): 149-156.

Riedel, W.J., Klaassen, T., Griez, E., Honig, A., Menheere, P. & van Praag, H.M. 2002. Dissociable hormonal, cognitive and mood responses to neuroendocrine challenge: Evidence for receptor-specific serotonergic dysregulation in depressed mood. Neuropsychopharmacology 26(3): 358-367.

Sarahroodi, S., Esmaeili, S., Mikaili, P., Hemmati, Z. & Saberi, Y. 2012. The effects of green Ocimum basilicum hydroalcoholic extract on retention and retrieval of memory in mice. Ancient Science of Life 31(4): 185-189.

Seifhosseini, S., Mehrdad, J., Ali, M. & Aazami, N.S. 2011. The effect of scopolamine on avoidance memory and hippocampal neurons in male wistar rats. Basic and Clinical Neuroscience 3: 9-15.

Seyed, M.A., Ayesha, S., Azmi, N., Al-Rabae, F.M., Al-Alawy, A.I., Al-Zahrani, O.R. & Hawsawi, Y. 2021. The neuroprotective attribution of Ocimum basilicum: A review on the prevention and management of neurodegenerative disorders. Future Journal of Pharmaceutical Sciences 7: 139.

Shakeri, F., Hosseini, M. & Ghorbani, A. 2019. Neuropharmacological effects of Ocimum basilicum and its constituents. Physiology and Pharmacology 23: 70-81.

Sheffler, Z.M., Reddy, V. & Pillarisetty, L.S. 2021. Physiology, neurotransmitters. StatPearls. Treasure Island (FL): https://www.ncbi.nlm.nih.gov/books/NBK539894/

Singh, V., Krishan, P. & Shri, R. 2018. Improvement of memory and neurological deficit with Ocimum basilicum L. extract after ischemia reperfusion induced cerebral injury in mice. Metabolic Brain Disease 33(4): 1111-1120.

Singh, V., Kahol, A., Singh, I.P., Saraf, I. & Shri, R. 2016. Evaluation of antiamnesic effect of extracts of selected Ocimum species using in vitro and in vivo models. Journal of Ethnopharmacology 193: 490-499.

Spilman, P., Descamps, O., Gorostiza, O., Peters-Libeu, C., Poksay, K.S., Matalis, A., Campagna, J., Patent, A., Rao, R., John, V. & Bredesen, D.E. 2014. The multi-functional drug tropisetron binds APP and normalizes cognition in a murine Alzheimer's model.  Brain Research 1551: 25-44.

Srivastava, S., Cahill, D.M., Conlan, X.A. & Adholeya, A. 2014. A novel in vitro whole plant system for analysis of polyphenolics and their antioxidant potential in cultivars of Ocimum basilicum. Journal of Agri and Food Chemistry 62(41): 10064-10075.

Sudweeks, S.N., Hooft, J.A. & Yakel, J.L. 2002. Serotonin 5-HT(3) receptors in rat CA1 hippocampal interneurons: Functional and molecular characterization. The Journal of Physiology 544(Pt 3): 715-726.

Suo, L. & Wang, M. 2021. Dexmedetomidine facilitates the expression of nNOS in the hippocampus to alleviate surgery‑induced neuroinflammation and cognitive dysfunction in aged rats. Experimental and Therapeutic Medicine 22(3): 1038.

Taglialatela, G., Hogan, D., Zhang, W.R., Dineley, K.T. 2009. Intermediate- and long-term recognition memory deficits inTg2576 mice are reversed with acute calcineurin inhibition. Behavior Brain Research 200: 95-99.

Vlase, J.L., Benedec, D., Hanganu, D., Damian, G., Csillag, I., Sevastre, B., Mot, A.C., Silaghi-Dumitrescu, R. & Tilea, I. 2014. Evaluation of antioxidant and antimicrobial activities and phenolic profile for Hyssopus officinalis, Ocimum basilicum and Teucrium chamaedrys. Molecules 19(5): 5490-5507.

Wallace, T.L., Ballard, T.M., Pouzet, B., Riedel, W.J. & Wettstein, J.G. 2011. Drug targets for cognitive enhancement in neuropsychiatric disorders. Pharmacology Biochemistry and Behavior 99(2): 130-145.

Warburton, E.C., Koder, T., Cho, K., Massey, P.V., Duguid, G., Barker, G.R.I., Aggleton, J.P., Bashir, Z.I. & Brown, M.W. 2003. Cholinergic neurotransmission is essential for perirhinal cortical plasticity and recognition memory. Neuron 38: 987-996.

Winblad, B. 2005. Piracetam: A review of pharmacological properties and clinical uses. CNS Drug Reviews 11(2): 169-182.

Xiao, J., Li, S., Sui, Y., Wu, Q., Li, X., Xie, B., Zhang, M. & Sun, Z. 2014. Lactobacillus casei-01 facilitates the ameliorative effects of proanthocyanidins extracted from lotus seedpod on learning and memory impairment in scopolamine-induced amnesia mice. PLoS ONE 9(11): e112773.

Yamamoto, N., Yoshida, A., Taki, Y., Onoue, S., Kagawa, Y. & Yamada, S. 2011. Up-regulation of nicotinic and muscarinic receptor mRNA in rat bladder by repeated administration of nicotine in relation to the pharmacokinetics. Life Sciences 89(9-10): 343-348.

Yan, Z., Flores-Hernandez, J. & Surmeier, D.J. 2001. Coordinated expression of muscarinic receptor messenger RNAs in striatal medium spiny neurons. Neuroscience 103(4): 1017-1024.

Yanpallewara, S.U., Raib, S., Kumarb, M. & Acharya, S.B. 2004. Evaluation of antioxidant and neuroprotective effect of Ocimum sanctum on transient cerebral ischemia and long-term cerebral hypoperfusion. Pharmacology Biochemistry and Behavior 79(1): 155-164.

^*Corresponding author; email: azrina.azmi@ukm.edu.my