ORIGINAL ARTICLE
Year : 2023 | Volume
: 8 | Issue : 1 | Page : 65--73
Neuroprotective role of Sida acuta Burm. f. in scopolamine-induced memory impairment rat model: An electrophysiological and behavioral study
Jyoti Singh1, Prasanta Kumar Nayak2, Ashwini Kumar Kushwaha3, Dev Nath Singh Gautam1, Manmath Kumar Nandi4,
1 Department of Rasa Shastra and Bhaishajya Kalpana, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
2 Department of Pharmaceutical Engineering and Technology, Indian Institutes of Technology, Banaras Hindu University, Varanasi, India
3 Department of Dravyaguna, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
4 Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
Correspondence Address:
Manmath Kumar Nandi
Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, Uttar Pradesh
India
Abstract
BACKGROUND: In the present study, neuropharmacological effect of Sida acuta root extract was investigated by in vitro and in vivo experimental models. METHODS: In in vitro electrophysiological study, hippocampal slices of the albino rats’ brain were treated with three different concentrations of the extract (0.25, 0.5, and 1 mg/mL). Field excitatory postsynaptic potential slope (mV/ms) was assessed. In in vivo study, plant extract was given at three different doses (50, 100, and 200 mg/kg b.w., p.o.). Piracetam (200 mg/kg i.p.) was used as a standard drug and scopolamine (1 mg/kg, i.p.) was used to induce dementia in rats. The effect of extract was assessed using elevated plus maze and Barnes maze model. RESULTS: The in vitro result showed reduction in the amplitude of field excitatory postsynaptic potential slope after wash in the extract at 0.25 mg/mL, 0.5 mg/mL, and 1 mg/mL due to the partial blockage of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. In vivo study reveals that scopolamine-treated rats exhibited delayed latency time in elevated plus maze and Barnes maze, as well as numbers of error were also increased in Barnes maze as compared to the control. Animals treated with piracetam and root extract (200 mg/kg) reduced the effect of scopolamine-induced dementia to a great extent. CONCLUSION: This finding reveals that Sida acuta root extract has cognitive enhancing activity.
How to cite this article:
Singh J, Nayak PK, Kushwaha AK, Gautam DN, Nandi MK. Neuroprotective role of Sida acuta Burm. f. in scopolamine-induced memory impairment rat model: An electrophysiological and behavioral study.J Drug Res Ayurvedic Sci 2023;8:65-73
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How to cite this URL:
Singh J, Nayak PK, Kushwaha AK, Gautam DN, Nandi MK. Neuroprotective role of Sida acuta Burm. f. in scopolamine-induced memory impairment rat model: An electrophysiological and behavioral study. J Drug Res Ayurvedic Sci [serial online] 2023 [cited 2023 Mar 28 ];8:65-73
Available from: http://www.jdrasccras.com/text.asp?2023/8/1/65/366298 |
Full Text
Introduction
Dementia is an age-related neurodegenerative disorder with its prevalence in the patients above 90 years (36%) followed by patients lying within 60–65 years’ age group (10%).[1] Because of dementia, approximately 24 million people have suffered all over the country so far.[2] Dementia is associated with various brain diseases characterized by impairment in cognitive abilities due to progressive neurodegeneration and a loss of neurons in distinct brain areas.[3] This leads to behavioral disturbances. Patients became more agitate, aggressive, depressive, and anxious and affected with sleep disorder.[4] This manifestation is further characterized by a loss of memory, disturbance in psychological activity, and irregularities in language.[5]
The central cholinergic pathways are responsible for the learning and memory of an individual.[6] Glutamate and γ-aminobutyric acid are two most important neurotransmitters present in the central nervous system responsible for the formation of memory. The three classes of glutamate receptors are α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, kainate, and N-methyl-D aspartate receptors. AMPA receptor plays an impotent role in synaptic plasticity such as long-term potentiation (LTP) and long-term depression (LTD).[7]
Most commonly prescribed medicines for dementia are tacrine, galantamine, donepezil, and rivastigmine, which are mostly associated with various side effects.[8] Therefore, there is a need to find an efficient and safe drug from the natural origin to treat dementia with minimum side effects.
Plants and its preparation have been used since ancient time in India for the maintenance of good health. The biological properties of the plants have long been known. Several medicinal plants are reported for traditional healing. As stated by World Health Organization (WHO), 80% of the world populace relies mainly on a traditional system of medicines.[9]
Medicinal plants such as Sida acuta (Malvaceae) is traditionally used for the treatment of nervous disorders.[10],[11] It is an erect perennial shrub. It is native of Central America, but today, it is distributed in several parts of India.[12] The plants contain various phytochemical constituents such as alkaloids, phytosterols, tannins, flavonoids, saponins, terpenes, and phenolics, etc., which are responsible for various pharmacological activities,[10] but the neuroprotective properties of the S. acuta root are not evaluated experimentally. Therefore, the present study was designed to assess the neuroprotective activity of the S. acuta root extract (SARE) by in vitro and in vivo experimental models.
Materials and Methods
Collection and preparation of the extract
Fresh roots of S. acuta were gathered locally from Barkachha, Mirzapur, Uttar Pradesh. The roots were authenticated by Central National Herbarium, Botanical Survey of India, Howrah 711103, West Bengal (No.: CNH/2017/Tech.II/49 specimen No. JS-02, dated October 17, 2017).
After proper cleaning, the fresh roots were shade dried for 2 weeks. The dried plant material was grounded to coarse powder by pulverizer (M/s Harrison’s Pharma Pvt. Ltd., Delhi, India) at Ayurvedic Pharmacy, Banaras Hindu University. The coarse powder was extracted by cold maceration with hydro-alcoholic solvent (70:30) for a period of 72 h. The collected extract was concentrated in rotary vacuum evaporator below 60°C to get semisolid residue and stored in desiccators for further study.[13]
Physicochemical parameters
The powdered material of S. acuta was subjected to analyze various physicochemical parameters such as ash value, extractive value, foreign matter, foaming index, fiber content, loss on drying (LOD), etc. All these parameters have been done as per the WHO guidelines 2002.[14]
Photochemical study
A preliminary as well as thin-layer chromatography was performed to determine the secondary metabolites present in the plant, following the procedure described previously.[15]
Fourier transform infrared spectroscopy
The absorption spectrum of the SARE was taken by Fourier transform infrared spectroscopy (FTIR) (Varian: Cary-100 Bio software), from the region of 4,000–500 cm−1.
Experimental animals
Albino rats (150–200 g) of both sexes were obtained from animal house of Institute of Medical Sciences, Banaras Hindu University, Varanasi, and kept in polypropylene cages. The rats were fed with pellet diet and habituated to experimental conditions for 7 days before the experiment. The experiment was done after the approval of the Animals Ethics Committee of Banaras Hindu University, Varanasi (No. Dean/2017/CAEC/253).
Drugs and chemicals
All drugs were bought from authorized dealers and were of analytical grade. NaCl, KCl, NaH2PO4, NaHCO3, CaCl2, MgCl2, glucose, scopolamine, and piracetam (PIRA) were obtained from Sigma Aldrich (USA).
In vitro electrophysiology
Slice preparation
Rats were quickly decapitated under CO2 anesthesia. Brain were immediately removed and cooled in ice cold pregassed (95% O2–5% CO2) artificial cerebrospinal fluid (ACSF). Hippocampi were carefully removed from the rat’s brain and dissected in 400 μm transverse sections by using a drop-blade tissue chopper.[16]
Electrophysiological
Rat brain slices were placed between nylon mesh in the recording chamber maintained at 31°C ± 1°C and continuously superfused with oxygenated ACSF at the rate of 2–2.5 mL/min. Prior to recording, slices were left undisturbed for 1.5 h. In the Schaffer collateral-commissural pathway (stratum radiatum) of hippocampal region CA1 (cornu ammonis 1), bipolar stimulating electrodes had been positioned in Schaffer collateral-commissural pathway (stratum radiatum) of hippocampal region CA1, by visualizing through Olympus stereo microscope.[17] Biphasic electrical stimulation applied with intensity ranging from 2 to 25 V at 0.1 ms pulse of 0.1 Hz. Low-impedance 50 μm tungsten recording microelectrodes positioned into the dendritic field (stratum radiatum) of area CA1 up to 100 μm. Field excitatory postsynaptic potential (EPSP) slope (mV/ms) was assessed.[18]
Input/output paradigms were conducted before and after the SARE. The input stimulation intensity was started with a very low voltage (2V) on the stimulator and gradually increased (consecutive increase of 1 V up to 10 V and then after stimulated with 12, 15, 20, and 25 V) until the hippocampal response exhibited no further change in amplitude. After input/output paradigms, baseline was conducted at the submaximal voltage of input/output for 15 min; further SARE at 1 mg/mL, 0.5 mg/mL, and 0.25 mg/mL concentration was wash-in for 15 min followed by a washout period of 30 min to allow the responses to come to normal[19] [Figure 1].{Figure 1}
In vivo study
Experimental design
A total of 36 rats of both sexes were used for this study. Distilled water (DW) was used as vehicle for control (1 ml/kg; p.o.). Scopolamine hydrobromide (SCP) was dissolved in normal saline and given by intraperitoneal route (i.p.) on the fifth and 12th day of treatment, before 1 h of the experiments, at 1 mg/kg dose.[20] Distilled water (DW) was used as a vehicle to dissolve the SARE and given by oral route to the rats. The extract was given daily for 12 days at 50 mg/kg, 100 mg/kg, and 200 mg/kg.[11],[21],[22] PIRA at 200 mg/kg was used as a standard drug and given daily by i.p. route.[23],[24] Rats were categorized into six groups having six animals in each group.
Group I: Control: vehicle (DW 1 ml/kg; p.o.).
Group II: Negative control: SCP was given to the rats (1 mg/kg [i.p.])
Group III: Positive control: treated with SCP 1 mg/kg (i.p.) + PIRA 200 mg/kg (i.p.)
Group IV: SCP 1 mg/kg (i.p.) + SARE 50 mg/kg (p.o.)
Group V: SCP 1 mg/kg (i.p.) + SARE 100 mg/kg (p.o.)
Group VI: SCP 1 mg/kg (i.p.) + SARE 200 mg/kg (p.o.).
Barnes maze test
Barnes maze (BM) is a circular wooden platform having 20 holes, out of which one hole is attached with an escape box. Lighting was placed above the maze, and visual cues such as any color or shape were placed around one side of the maze. Rats were placed on the center of the maze and time taken to find the escape box, that is, escape latency (EL), was measured. During the trial period, rats were learned to find the escape box so that rats can enter directly into the escape box without entering into incorrect holes. EL and the number of errors were measured.[25]
Elevated plus maze test
Elevated plus maze (EPM) was used to evaluate the cognitive behaviors of rats. It is a plus shape instruments having four arms, in which two arms are open (50 × 10 cm) and two are closed (50 × 10 × 40 cm). It is 50 cm above the floor and kept in a dimly light room. On the eighth day, all the animals were kept individually at the outer edge of the open arm. Transfer latency (TL) for each rat was recorded that is time required to reach the animals in any of the closed arms with all its four leg. The cut-off time was 180 s for each rat. After 24 h, the TL was again recorded. The reduction of the TL indicates the improvement in memory.[26]
Statistical analysis
Data obtained by EPM and BM were scrutinized using two-way analysis of variance monitored by Bonferroni’s multiple compared tests. P < 0.05 was considered statistically significant.
Results
Physicochemical parameters
The physicochemical parameters such as foreign matter, LOD, ash value, extractive value, fiber content, pH, etc., were studied and mentioned in [Table 1].{Table 1}
Fluorescence analysis
The powder of S. acuta showed different colors under day light and ultraviolet light (at 254 nm and 365 nm) after treated with various chemical reagents. The results of fluorescent studies were given in [Table 2].{Table 2}
Phytochemical screening
For the qualitative assessment of various classes of phytoconstituents, preliminary and thin-layer chromatography was done. The finding showed that the plant is rich in alkaloid, flavonoids, phenol, terpenes, etc. [Table 3] and [Table 4].{Table 3} {Table 4}
Functional group analysis
Different peaks were observed in FTIR spectrum of SARE [Figure 2]: 3391 cm-1 (N–H str; primary amine), 1631 cm-1 (C=C str; alkene), 1376 cm-1 (O–H bending; alcohol), 1228 cm-1 (C–O str; alkyl aryl ether), 1085 cm-1 (C–O str; aliphatic ether), and 779 cm-1 (C–H bending; 1,2,3 trisubstituted).{Figure 2}
Hippocampal electrophysiology
In this study, hippocampal slices of the rat brain were treated with three different concentrations of SARE (0.25 mg/mL, 0.5 mg/mL, and 1 mg/mL). From the data of EPSP slope, we found the decrease in EPSP slope after passing the SARE at 0.25 mg/mL, 0.5 mg/mL, and 1 mg/mL [Figure 3] and [Figure 4].{Figure 3} {Figure 4}
Effect of SARE on behavioral performance
BM test
During the training days, EL and total errors were measured and analyzed. Latency and total errors simultaneously decreased from the first to seventh day during training in each group [Figure 5]. After acquisition phase, EL was measured on the fifth and 12th day. In comparison to the control, on the fifth day and 12th day, SCP (P < 0.001), SARE 50 mg/kg (P < 0.001), and SARE 100 mg/kg (P < 0.05) showed significant differences [Figure 6]. The total errors were also noted on the fifth and 12th day. In comparison to control, on the fifth day, SCP (P < 0.001), SARE 50 mg/kg (P < 0.001), and SARE 100 mg/kg (P < 0.01) showed significant differences, whereas on the 12th day, SCP (P < 0.001), SARE 50 mg/kg (P < 0.001), and SARE 100 mg/kg (P < 0.05) showed significant differences [Figure 7].{Figure 5} {Figure 6} {Figure 7}
EPM test
In this experiment, the effect of SARE on SCP-induced dementia was examined. TL was measured on the eighth and ninth day of SARE treatment. TL on the eighth day represented the learning acquisition, whereas TL on the ninth day indicated the long-term memory performance.
In comparison to control, on the eighth day, SCP (P < 0.001), SARE 50 mg/kg (P < 0.001), and SARE 100 mg/kg (P < 0.05) showed significant differences, and on the ninth day, SCP (P < 0.001) and SARE 50 mg/kg (P < 0.001) showed significant differences [Figure 8].{Figure 8}
Discussion
S. acuta is traditionally used for the treatment of liver diseases, urinary diseases, blood disorders, and nervous diseases. In the present study, neuropharmacological effect of SARE was investigated by in vitro and in vivo experimental models.
Physicochemical parameters are used to confirm the quality and authenticity of the drug. The total moisture content was 4% (w/w), which is very less; hence it could prevent bacterial and fungal growth.[27] Total ash value was found to be 3.25% (w/w), which indicates the presence of negligible quantity of minerals and extraneous earthy material. Acid insoluble ash and water soluble ash were found to be 0.5% and 2.25% (w/w), which indicates the absence of siliceous material and inorganic compound.[28] The extractive value found in ranks is chloroform > ethanol > water > petroleum ether. Thus, extraction was designed in hydroalcoholic solvent (70:30).[29]
Preliminary phytochemical study gave valuable information about the presence of secondary metabolites in SARE such as alkaloids, flavonoids, steroids, phenolic compounds, proteins, etc. To confirm the presence of these phytoconstituents, thin layer chromatography study was done.[30]
Hippocampal electrophysiological technique allows establishing basic neurophysiological characteristics of the neurons and is considered as a functional tool to study alterations in neural activity. The hippocampal slice is especially renowned for the study of synaptic plasticity mechanisms involved in learning and memory. In the hippocampal electrophysiology, field EPSP slope was measured by selecting the steepest part of negative going potential. Hippocampal slices (400 μm thick) were perfused with oxygenated ACSF to keep the cells alive. EPSPs were provoked by Schaffer collateral stimulation through a polar stimulation electrode (S) and distinctive waveforms recorded as extracellular field potentials with wire electrodes placed in the stratum radiatum of the CA1 region (R). The underlying mechanism behind LTP in hippocampal CA1 region begins with tetanic stimulation of afferent fibers resulting in excessive glutamate release into the synaptic cleft. This glutamate is able to bind to postsynaptic glutamate receptors, in particular the AMPA receptor, resulting in sodium influx into the postsynaptic terminal, which depolarizes the postsynaptic membrane and produces an EPSP.[31] The generation of the EPSP is a graded response and depends on the magnitude of glutamate release that is determined by the number of presynaptic fibers being stimulated LTP[32] and LTD at the hippocampal glutamatergic synapses (CA3–CA1) are the basis of physiological mechanisms underlying learning and memory.[33],[34]
In the present study, slices were perfused with ACSF for 15 min (baseline), SARE wash-in (0.25, 0.5 and 1 mg/mL) for 15 min, and washout for 30 min. Input/output (I/O) paradigms were recorded before and after SARE, and the reduction in the amplitude of EPSP was found. When SARE wash in through ACSF, reduction in the amplitude of EPSP was found, which is irreversible at 0.25 mg/mL and 1 mg/mL. Reduction in the amplitude is due to the partial blockage of AMPA receptors. These preliminary data indicate that SARE is antagonist of AMPA receptors and may refer as a pharmacological preconditioning agent, which impart tolerance to the damage and prevent cell death.[18],[35]
In BM, EL and total errors decreased along the seven consecutive training days, showing the improvement in learning ability of the rats. SCP is a muscarinic acetylcholine receptor antagonist, used for inducing dementia in rats.[36] Rats treated with SCP exhibited delayed latency time as compared to the control in EPM and BM; also numbers of error were increased in BM after administration of SCP. Rats treated with PIRA and SARE at 200 mg/kg are nonsignificant to the control, which means that the extract has reduced the effect of SCP to a great extent at 200 mg/kg. All the finding revealed that SARE may have cognitive enhancing effect.
Conclusions
In summary, the obtained result indicates that the SARE is antagonist of AMPA receptors, which exhibit pharmacological preconditioning activity. The SARE recovers the SCP-induced dementia in rats. The drug may act as a neuroprotective drug, and the presence of flavonoids and phenolic compounds in the extract could be responsible for these effects, but further study is necessary to find out the active compound responsible for the neuropharmacological activity and their mechanism of action.
Acknowledgments
The authors are thankful to R. Gogoi, Botanical Survey of India, Howrah, West Bengal, India, for proper identification and authentication of the plant specimen and Dr. Narendra Kumar Singh, Babu Banarasi Das University, School of Pharmacy, for helping in analytical study of the plant material.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Authors’ contributions
MKN conceived the idea of this experimental study as well as JS performed the study and wrote the article. PKN helped in the experimental study and results analysis. AKK, DNSG, and MKN edited and proofread the document. The entire team approved the submission of the final article. All authors have read and agreed to the published version of the article.
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