The Effect of Metformin in Experimentally Induced Animal Models of Epileptic Seizure
Table 3
The effects of metformin against epileptic seizure on different animal models.
Model
Methods and intervention
Main treatment outcomes
References
Chronic phase of pilocarpine-induced seizures in model of TLE (Wistar rats)
After induction of seizure, animals were randomly divided into the following: (a) the control group received vehicle, (b) the epileptic group received 360 mg/kg IP pilocarpine, and (c) the treatment group received IP injections of metformin (250 mg/kg/day).
7th day post-treatment, metformin Counteract touch-response, pick-up, and finger snap Decreased BDNF and Trk expression significantly Increased expression of CtBP after drug administration Increased the protein expression of p-AMPK Decreased the protein expression of p-mTOR
Oxidative damage and PTZ-induced kindling (adult male mice)
Animals were randomly divided into (a) control group, (b) PTZ group, (c) the PTZ + MET group that received MET in dose of 200 mg/kg, and (d) the MET group that received 200 mg/kg of metformin alone.
Pretreatment with metformin: Significantly suppressed the progression of kindling as evidenced by the decrease in seizure scores. Improved the cognitive performance. A noticeable decrement in the concentration of malondialdehyde (MDA). There is also substantial upregulation of glutathione (GSH) level
PTZ-induced apoptotic neurodegeneration in human cortical neuronal cells.
HCN-2 cell line derived from the brain tissue of patients having intractable seizures. HCN-2 cortical cells cultured and further divided into (a) control group, (b) PTZ (30 mM) group, and (c) metformin (20 mM) + PTZ group.
Metformin notably reversed the effect of neuronal cell loss compared to the control group. It also prevented PTZ-induced apoptotic neuronal loss by decreasing the expression of caspase-3 and 9. Besides, metformin showed its protective effect by reversing the effect of PTZ-induced neurodegeneration.
PTZ-induced seizures in a malin knockout (KO) model of Lafora disease (male mice)
Four groups of 16 adult male mice were analyzed per condition: (a) wild-type mice, (b) malin knockout mice, (c) malin knockout mice with 4-PBA treatment, and (d) malin knockout mice with metformin treatment.
Metformin treatments decreased the overall number (%) of mice developing seizures. Decreasing this percentage below wild-type levels after metformin treatment and PTZ-induced mortality also decreased to 0%. Metformin treatments increased the latency for PTZ-induced seizure onset and shorten seizure lengths in malin KO mice Metformin treatment also attenuated the hyperexcitability detected in mice lacking the malin protein.
Biochemical parameters in PTZ- induced epileptic rats
Rats were divided into 3 groups: (a) group 1 served as control, (b) group 2 were treated with glibenclamide at a dose of 5 mg/kg, and (c) group 3 were treated with metformin at a dose of 150 mg/kg.
Only rats treated with metformin showed a decrease in serum glucose level after 3 and 24 hours, increasing after a week and returning near normal. Metformin treated group showed a significant increment of serum TC level after 3, 24 hours, without effect after a week. Metformin also displayed a substantial upsurge of serum TP level after 3 hours. Further, the metformin-receiving group showed a marked reduction in serum albumin and globulin levels
Kainic acid and PTZ-induced seizures (adult male mice)
The acute seizures were induced by IP injection of PTZ (70 mg/kg) while the chronic seizure model was established by kainic acid.
Mice that received metformin treatment for 30 days Behavioral assay showed that the Racine score was not significantly different between metformin-treated and control groups. The incidence of GTCS was also not different in the metformin group (8/12) and control group (9/12) (). But mice treated with metformin displayed a substantial reduction of mortality (3/8) compared to the control group (8/9). Metformin-treated mice showed a significantly increment in p-AMPK level in the PTZ-induced acute seizure model. Chronic metformin treatment facilitates seizure termination in PTZ-induced acute seizures and also promotes termination of chronic seizures (by reducing the duration of SLE). Long-term metformin treatment also showed considerable upregulation of the level of p-AMPK.
Yeast/cornmeal/agar media- induced seizure in D. melanogaster
Two-day old seizure-sensitive flies were fed (1 g standard yeast/agar media or 1 g of media + 25 mg of metformin) for 2 days. The movement or SLA using the HandyAvi software program was recorded.
The seizure-sensitive flies in the metformin-receiving group showed a reduction in the SLA path length expressively as compared to control. The SLA duration was also significantly reduced whereas SLA velocity was not changed considerably.
After hybridization, heterozygous mice of Epm2b+/- (used as control) and homozygous Epm2b-/- (malin KO) were used. 2% trehalose and 20 mM of 4-PBA as positive control and 12 mM of metformin were administered as a test substance.
After 2 months of treatment The metformin-receiving group displayed an enhanced activation of AMPK in both control and KO malin mice. But metformin-treated animals produced an insignificant rise in the level of chaperone BiP/GRP78. Treatment with metformin also showed a noticeable decrement of the number of PAS+ aggregates. Both 4-PBA and metformin treatments prevented the neuronal loss and hippocampal gliosis compared to the trehalose-treated group. 4-PBA or metformin also ameliorates some Epm2b-/- neuropsychiatric symptoms.
The rats were randomly divided into (a) control (saline), (b) SE (PTZ), (c) SE + salubrinal, (d) SE + GSK2656157 (GSK), (e) SE + metformin (200 mg/kg); (/group).
The metformin-receiving group showed a marked reduction in CHOP expression () compared to the SE group. Even if a reducing tendency was observed at 24 hours following metformin treatment, CHOP expressions were not significantly different in all of the treatment groups between 6 and 24 hours. On top of CHOP, eIF2α and PERK levels were also reduced in the metformin-treated group compared to SE control. The rate of apoptosis was meaningfully reduced in the metformin-receiving group as compared to the SE group.
Animals were randomly allocated into ( rats/group) (i) normal group: received saline, (ii) metformin group like normal group but received metformin (200 mg/kg) pretreatment daily for two weeks, (iii) PTZ group: rats received PTZ (50 mg/kg) on alternate days for two weeks, and (iv) metformin + PTZ group: like PTZ group but received metformin (200 mg/kg) pretreatment daily for two weeks.
The metformin-treated PTZ group showed meaningful decrement of seizure scores compared to the PTZ group. The metformin-treated PTZ group also displayed noticeably longer values of the seizure onset latency than the PTZ group in almost all trials. Compared to the first trial, the values of the seizure duration in all other trials showed a gradual significant increase in PTZ-administered groups. The metformin-receiving animals of PTZ groups exhibited substantial reduction in seizure duration compared to the PTZ group in all recorded trials. The metformin-treated PTZ group presented a noteworthy reduction of MDA and substantial upregulation of GSH level in the CA3 region of the hippocampus compared to the PTZ group. Conversely, metformin treatment failed to show a significant increase in catalase level as compared to the PTZ group. The metformin-receiving PTZ group displayed meaningful downregulation of apoptotic protein, caspase-3, and β-catenin in the hippocampal area compared to PTZ groups. In histopathological analysis, the metformin-treated group also showed a normal shape and number of neurons as well as a substantial reduction of abnormal neurons in the brain tissues. Compared to the PTZ group, the metformin-treated group exhibited a meaningful downregulation of α-synuclein expression in the CA3 region of the hippocampus.
Electrical kindling of the amygdala; model of TLE in Wistar rats
Animals were grouped into the following: fed ad libitum (AL; ), fed ad libitum plus metformin (AM; ), and rats subjected to 15% caloric restriction (CR) plus metformin (CM; ); metformin administered at a dose of 100 mg/kg daily for 5 days/week till the end of the experiment.
The metformin plus CR- (CM-) treated group showed a significant increment of the after-discharge (AD) threshold, while its length was reduced, hence diminishing the total cumulative AD duration than the AM and AL group. CM also reduced the time spent in seizure stage 5. Consequently, the time spent in generalized convulsive seizures was reduced (stages 4-5). Metformin alone (AM) substantially upregulated AMPK phosphorylation in the neocortex, while CM amplified the phosphorylation of AMPK both in the neocortex and in the hippocampus. AM and CM administration also augmented the expression of the mTOR gene, but reduced PKB phosphorylation in the neocortex and the hippocampus.
