ACCENT JOURNAL OF ECONOMICS ECOLOGY & ENGINEERING Peer Reviewed and Refereed Journal, ISSN NO. 2456-1037
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Vol. 07, Issue 02,February 2022 IMPACT FACTOR: 7.98 (INTERNATIONAL JOURNAL) 40 EXPLORING THE CORRELATION BETWEEN LAMOTRIGINE AND GABA LEVELS IN
CEREBROSPINAL FLUID: A LINEAR RELATIONSHIP ANALYSIS
Dr. Kokkula Satyanarayana
Professor, Department of Pharmacognosy, Princeton College of Pharmacy, Hyderabad, Telangana, India
Sunitha Chintala
Asso. Professor, Department of Pharmacognosy, Princeton College of Pharmacy, Hyderabad, Telangana, India
Abstract- Anxiety, insomnia, depression, and bipolar disorder can all be treated with the assistance of GABA-mediated neurotransmission. The point of the current review is to supply proof about neurochemical impacts of intense lamotrigine therapy on GABA and L- glutamic corrosive levels in the cerebrospinal liquid of Wistar Pale skinned person rodents and the association of cholinergic framework. Microdialysis experiments were carried out in a conscious rat model one day after concentric microdialysis probes were inserted into the lateral ventricles of rats. Either 20 mg/kg lamotrigine or physiological saline were injected into the rats' peritoneum. For evaluating the cholinergic contribution 0.5 mg/kg physostigmine or 2 mg/kg atropine sulfate pre-medicines were given before lamotrigine infusion. High Performance Liquid Chromatography was used to analyze the dialysate concentrations of GABA, L-glutamic acid, and lamotrigine. While lamotrigine treatment significantly increased GABA concentrations (p 0.05), saline did not alter L-glutamic acid or GABA concentrations. Physostigmine or atropine sulfate pretreatment had no significant effect on GABA or L-glutamic acid levels. Lamotrigine-induced GABA levels were unaffected by pre-treatments with physostigmine or atropine sulfate. Given that there is a linear relationship between lamotrigine and GABA, the findings may suggest that lamotrigine- induced GABA contributes to the pharmacological effects of lamotrigine. However, lamotrigine-induced GABA release is unaffected by the central cholinergic system.
Keywords: Microdialysis, the cholinergic system, glutamate, and the conscious rat model.
1 INTRODUCTION
As a relatively new antiepileptic, lamotrigine is currently being widely used as the first-line treatment for certain types of seizures, such as Lennaux- Gestaut syndrome, grand or petit mal seizures, and myoclonus. Additionally, lamotrigine has been widely favored for bipolar disorders. As the brain's primary inhibitory neurotransmitter, amino butyric acid (GABA) has been linked to the pathophysiology of bipolar disorder.
Lamotrigine's anti-glutamergic effects may also be influenced by GABAergic potentiation, according to previous research.
Lamotrigine blocks the exocytosis of these excitatory amino acids by inhibiting Na+ channels, thereby reducing the release of glutamate and aspartate.
The job for restraint of Ca2+ channels was additionally illustrated. Lamotrigine has previously been shown to reduce glutamate and increase GABA release without affecting Na+ or Ca2+ channels in rat entorhinal cortex using whole patch clamped cells. In rat amygdale cells, it was also reported that lamotrigine affects presynaptic Ca2+ influx, which in turn
suppresses GABAA-mediated
neurotransmission. Lamotrigine likewise diminishes veratrineor electrically animated arrival of endogenous glutamate and [3H]-GABA, [3H]-5-hydroxytriptamine and [3H]-dopamine in rodent cortical cuts. Ex vivo studies, on the other hand, showed that while acute lamotrigine did not affect the amount of GABA or taurine
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Vol. 07, Issue 02,February 2022 IMPACT FACTOR: 7.98 (INTERNATIONAL JOURNAL) 41 in hippocampal tissue, chronic treatment
with the drug did.
The relationship between the cholinergic system and GABAergic transmission in the central nervous system has been studied for a long time.
GABA and its analogues directly inhibit cortical acetylcholine release in freely moving guinea pigs and electrically stimulated slices, as previously demonstrated in vivo and in vitro. Some findings suggested that acetylcholine exerts direct inhibitory effects on GABA release at least in other brain areas and in the periphery. Although the excitation of GABAergic inter neurons in the cerebral cortex has been attributed to the local inhibitory effects of acetylcholine.
By measuring the amino acids dialyzed through microdialysis probes implanted into the lateral ventricles of conscious rats, this study aims to monitor the time-course changes of GABA and L- glutamic acid in rat cerebrospinal fluid produced by lamotrigine treatment and to demonstrate the potential modulatory effect of the cholinergic system on the lamotrigine-induced amino acid release.
2 MATERIALS AND METHODS 2.1. Animals and laboratory
Both sexes of Wistar albino rats weighing between 250 and 275 g were used, and they were obtained from Marmara University's Experimental Research and Animal Laboratory. Before the experiments took place (16.12.2005 - 63.2005.mar), the Ethical Committee for Experimental Animals at Marmara University granted their approval. The animals were fed standard animal food and water ad libitum in a temperature- controlled room with a 12-hour light and dark cycle.
2.2 Drugs used in the study
All medications were provided from Sigma Synthetic (USA) with the exception of lamotrigine (provided benevolent from GlaxoSmithKline, Turkey). Before being
injected, physiological saline was used to dissolve lamotrigine.
2.3 Stereotaxic Surgery and Microdialysis
As previously mentioned, concentrated microdialysis probes were utilized. A stereotaxic frame (Stoelting, Model 51600, USA) and intraperitoneal ketamine (100 mg/kg) and chlorpromazine (1.0 mg/kg) mixture were used to anesthetize the rats.
The periosteum and cranium were cut from the skin of the scalp. The right lateral ventricle was the site of the probe's placement (lateral ventricle coordinates;
According to the Paxinos and Watson rat brain atlas, it is 3.8 mm ventral to the surface of the skull, 1.5 mm lateral to the midline, and 1.0 mm posterior to the bregma. Additionally, supporting screws were inserted, and dental acrylic cement was applied to the screws and the microdialysis probe. 24 hours after surgery, samples of intracerebral perfusion were collected.
Polyethylene tubings were attached to the microdialysis probes' inlet the day after they were placed to collect samples from a conscious rat model housed in a 42X42X20 cm plexiglass cage. Fake cerebrospinal liquid was conveyed consistently by means of 250 μl hamilton needle which was associated with a microinfusion siphon (KD Logical, USA). The pH of the artificial cerebrospinal fluid was set to 7, and its composition consisted of 2.5 mM KCl, 125 mM NaCl, 1.26 mM CaCl22H2O, 1.18 mM
MgCl26H2O, and 0.2 mM
NaH2PO42H2O. Filtering the artificial cerebrospinal fluid was done with nylon membrane filters of 0.4 m.
After an equilibration period of one hour, two basal samples were taken from Wistar rats in 0.25 ml ependorf tubes at a flow rate of 0.5 l/minute every 40 minutes. Five more samples were taken in succession after an intraperitoneal physiological saline injection was given. A similar convention was rehashed with
ACCENT JOURNAL OF ECONOMICS ECOLOGY & ENGINEERING Peer Reviewed and Refereed Journal, ISSN NO. 2456-1037
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Vol. 07, Issue 02,February 2022 IMPACT FACTOR: 7.98 (INTERNATIONAL JOURNAL) 42 lamotrigine (20 mg/kg), physostigmine
(0.5 mg/kg) or atropine sulfate (2 mg/kg).
During the microdialysis procedure, the rats were observed and atypical behaviors were noted. The dialysates were divided into two equal ependorf tubes for various High Performance Liquid Chromatography analysis methods and kept at -80oC.
Methylene blue was injected through the probe and the rats were decapitated after being anesthetized with ether. To verify the placement of the probe, the brains were sliced with a knife to observe the dye in the ventricles. In the data analysis, only the appropriate experiments were used.
3 DISCUSSION
The current study demonstrates that rats receiving 20 mg/kg of acute lamotrigine elevate GABA levels in their cerebrospinal fluid. In the past, Wheatley et al. reported that the rat tolerated this dose within the anticonvulsive range. We also used doses of 10 mg/kg in the initial experiments, but there was no change in GABA levels (data not shown), so we continued the study with the dose above. Morris and co.
also demonstrated that the plasma concentrations of lamotrigine attained by rats at this dose were comparable to those suggested for epileptic patients. The difference in doses between rats and humans may be due to this.
We also looked at how much lamotrigine was in the dialysates from the lateral ventricles. Lamotrigine levels in the cerebrospinal fluid also went up in tandem with the rise in GABA concentrations. Similar observations have been made in the past. The plasma concentrations of lamotrigine and the doses administered appear to have a linear relationship. Lamotrigine, like all antiepileptics, must cross the blood–brain barrier to work as an anticonvulsant. As a result, determining the drug concentration at the neuronal sites of action is required for the interpretation of the plasma levels of lamotrigine.
Lamotrigine rapidly appears in plasma after intraperitoneal administration (peak value at 0.25 hours), indicating rapid absorption from the peritoneal cavity. In addition, the rapid appearance of lamotrigine in the brain (peak value between 0.5 and 2 hours) suggests that it has already broken through the blood- brain barrier. Plasma and brain concentrations both show a monoexponential fall after peak values.
The linear relationship that was established between the drug in the brain and plasma as well as the parallel patterns that were observed in the plasma and brain profiles suggested that the distribution of lamotrigine is dependent on blood flow, suggesting that lamotrigine simply diffuses across the blood–brain barrier. Lamotrigine also exhibits a pattern that is comparable to that previously demonstrated in our study.
The cholinergic system's role in lamotrigine treatment's GABA response was another goal of this study. GABA concentrations in the cerebrospinal fluid decreased by a non-significant amount following an injection of lamotrigine following physostigmine, a cholinesterase inhibitor, pretreatment. Atropine sulfate, a muscarinic antagonist, also caused GABA levels to rise in a non-significant manner.
4 CONCLUSION
In conclusion, our findings may imply that the drug's anticonvulsant and mood- stabilizing effects are mediated by the lamotrigine-induced GABA response, whereas the cholinergic system does not appear to be involved—at least in healthy rats—and this issue needs further investigation.
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