Differential effects of levetiracetam on hippocampal CA1 synaptic plasticity and molecular changes in the dentate gyrus in epileptic rats

The interaction between finasteride and corticosterone levels: implications for depression-, and anxiety-like behavior and hippocampal synaptic plasticity in male rats

RATIONALE

Finasteride is FDA-approved for the treatment of hair loss and in older men for benign prostatic hyperplasia. However, some patients treated with finasteride reported suicidal ideation, depression, and anxiety. The neurobiological mechanisms underlying this are not clearly understood. Previously, we showed that short-term finasteride administration results in depression- and anxiety-like behaviour. Since finasteride treatment is long-term in the clinic, we examine the effects of chronic finasteride administration in the current study.

OBJECTIVE

This study aims to understand the behavioral, cellular, and molecular changes in male rats following 21 days of finasteride (3 mg, 10 mg, and 30 mg/Kg) administration.

METHODS

Depression-like behavior was evaluated using forced swim (FST), sucrose preference (SPT), and splash tests. Anxiety-like behavior was assessed using elevated plus maze (EPM), open field (OFT), light-dark (LDT), Vogel's conflict (VCT), and home cage emergence (HCET), and depression-related anxiety in novelty-suppressed feeding task (NSFT) tests. Hippocampal synaptic plasticity was assessed by field excitatory post-synaptic potentials (fEPSP) recordings in the Schaffer-collateral-CA1 synapses, and plasma corticosterone levels were estimated using ELISA.

RESULTS

Chronic finasteride administration induced depression-like and anxiety-like behavior in SPT and EPM, respectively, but not in the other paradigms. There was a modest decrease in long-term potentiation in the hippocampus. Interestingly, there was an increase in the plasma corticosterone levels with 6 days of finasteride administration, but not after 14 or 21 days of administration.

CONCLUSIONS

Chronic administration of finasteride did not induce a robust depression- and anxiety-like behavior and modestly affected synaptic plasticity. This could be potentially because of the adaptive response observed in the plasma corticosterone levels.

Comparing levetiracetam and zonisamide effects on rivastigmine anti-Alzheimer's activity in aluminum chloride-induced Alzheimer's-like disease in rats: Impact on α7 nicotinic acetylcholine receptors and amyloid β

BACKGROUND AND AIM

Alzheimer's disease (AD) is the most progressive form of neurodegenerative disease, which severely impairs cognitive function. The leading class of drugs used to treat AD is acetylcholinesterase inhibitors (AChE-Is) as Rivastigmine (RIVA), partially ameliorate its cognitive symptoms. Since epilepsy is a common comorbidity with AD, we explored the potential that new the antiepileptic drugs; Levetiracetam (LEV) and Zonisamide (ZNS) may possess an additional therapeutic benefit to RIVA in AlCl3-induced AD rat model.

MATERIALS AND METHODS

AlCl3 was used to provoke AD in rats which were then supplemented with treatment drugs for 2 weeks. Treated groups were: Control, AlCl3, RIVA, LEV, RIVA + LEV, ZNS and RIVA + ZNS. Then, the behavioral tests; passive avoidance (PA), Morris water maze (MWM) and novel object recognition (NOR) were conducted to assess cognitive behavior and memory. The Hippocampal Aβ assembly was thoroughly examined by histopathology and ELISA. α7 Nicotinic ACh receptors' (α7nAChRs) expression was assessed immunohistochemically and by real-time quantitative polymerase chain reaction (qPCR). Caspase 3 expression was also assessed by real-time qPCR in hippocampal tissues.

RESULTS

AlCl3 administration impaired memory and cognitive functions in rats, augmented hippocampal Aβ deposition, with subsequent neurodegeneration and α7nAChRs down-regulation. LEV, but not ZNS, administration significantly mitigated AlCl3-induced cognitive impairment probably through suppression of amyloid β (Aβ) deposition, enhancement of neurogenesis and α7nAChRs expression. When combined to RIVA, ZNS treatment negatively affected cognition possibly through its impact on hippocampal Aβ and subsequent neuronal damage.

CONCLUSION

Although our results indicated that neither LEV nor ZNS provided any extra benefit to cognitive enhancements in AD rats receiving rivastigmine, LEV demonstrated positive effects individually while ZNS had negative effects when combined with RIVA. As a result, this study suggests the use of LEV rather than ZNS for managing epilepsy in patients with AD given that Alzheimer's and epilepsy can coexist.

Seizure Cycles under Pharmacotherapy

OBJECTIVE

This study was undertaken to determine the effects of antiseizure medications (ASMs) on multidien (multiday) cycles of interictal epileptiform activity (IEA) and seizures and evaluate their potential clinical significance.

METHODS

We retrospectively analyzed up to 10 years of data from 88 of the 256 total adults with pharmacoresistant focal epilepsy who participated in the clinical trials of the RNS System, an intracranial device that keeps records of IEA counts. Following adjunctive ASM trials, we evaluated changes over months in (1) rates of self-reported disabling seizures and (2) multidien IEA cycle strength (spectral power for periodicity between 4 and 40 days). We used a survival analysis and the receiver operating characteristics to assess changes in IEA as a predictor of seizure control.

RESULTS

Among 56 (33.3%) of the 168 adjunctive ASM trials suitable for analysis, ASM introduction was followed by an average 50 to 70% decrease in multidien IEA cycle strength and a concomitant 50 to 70% decrease in relative seizure rate for up to 12 months. Individuals with a ≥50% decrease in IEA cycle strength in the first 3 months of an ASM trial had a higher probability of remaining seizure responders (≥50% seizure rate reduction, p < 10-7) or super-responders (≥90%, p < 10-8) over the next 12 months.

INTERPRETATION

In this large cohort, a decrease in multidien IEA cycle strength following initiation of an adjunctive ASM correlated with seizure control for up to 12 months, suggesting that fluctuations in IEA mirror "disease activity" in pharmacoresistant focal epilepsy and may have clinical utility as a biomarker to predict treatment response. ANN NEUROL 2024;95:743-753.

Repeated finasteride administration promotes synaptic plasticity and produces antidepressant- and anxiolytic-like effects in female rats

Finasteride is used in female-pattern hair loss, hirsutism, and polycystic ovarian syndrome. It inhibits 5α-reductase, which is an important enzyme in the biosynthesis of neurosteroids. The effects of finasteride treatment on mental health in female patients as well as the effects of repeated/chronic finasteride administration in female rodents are still unknown. Accordingly, in our study, we administered finasteride (10, 30, or 100 mg/Kg, s.c.) for 6 days in female rats and evaluated behavior, plasma steroid levels, and synaptic plasticity. Depression-like behavior was evaluated using forced swim test (FST) and splash test. Anxiety-like behavior was evaluated using novelty-suppressed feeding task (NSFT), elevated plus maze (EPM), open field test (OFT), and light-dark test (LDT). Plasma steroid levels were assessed using ELISA and synaptic plasticity by field potential recordings. We observed that finasteride decreased total immobility duration in FST, indicating antidepressant-like effect and decreased the latency to first bite in NSFT, showing anxiolytic-like effect. We also found a significant increase in plasma estradiol and a significant decrease in plasma corticosterone level. Furthermore, field potential recordings showed that finasteride increased hippocampal long-term potentiation. These results indicate that repeated finasteride administration in female rats may have antidepressant- and anxiolytic-like effect, which might be mediated by enhanced estradiol levels or decreased corticosterone levels. Further studies are required to validate the molecular mechanisms underlying the effects of finasteride in female rats. Understanding the mechanisms will help us in developing novel neurosteroid-based therapeutics in the treatment of neuropsychiatric disorders in women.

Impact of levetiracetam on cognitive impairment, neuroinflammation, oxidative stress, and neuronal apoptosis caused by lipopolysaccharides in rats

Introduction

Neuroinflammation is associated with the elevation of toxic proinflammatory mediators that promote neurodegeneration and subsequently affect cognition. Causes of inflammation in the neuronal cells are believed to initiate various neurodegenerative disorders, mainly Alzheimer's disease. Levetiracetam is a second-generation antiepileptic drug. There is evidence supporting the memory-enhancing effect of levetiracetam from numerous experimental and clinical studies. Therefore, this research focused on finding its protective effects against lipopolysaccharides prompted cognitive impairment and exploring possible mechanisms underlining their neuroprotection.

Methodology

Two doses (100 or 200 mg/kg) of levetiracetam were administrated orally for 30 days. Additionally, four doses (250 µg/kg) of lipopolysaccharide were injected peripherally to induce neurotoxicity. Behavioral tests were carried out using various maze models. At the end of the tests, brain tissues were collected for biochemical evaluations. Cholinergic, neuroinflammatory, apoptosis, and oxidative-related parameters were analyzed in the brain homogenate to explore the possible mechanisms of action of levetiracetam.

Results

In lipopolysaccharide-induced rats, levetiracetam indicated a reduction (p < 0.01) in transfer latency using the elevated plus-maze. An improvement (p < 0.01) in novel and familiar objects exploration time using novel object recognition test. A rise (p < 0.05) in novel arm entries and extended time spent in the novel arm using the Y-maze test. In extension, the levels of acetylcholine (p < 0.001), anti-inflammatory factors (transforming growth factor-β1; p < 0.01 and interleukin-10; p < 0.05), and an antioxidant (catalase; p < 0.01) were elevated in lipopolysaccharide-induced rats after the administration of levetiracetam. In contrast, inflammatory factors (cyclooxygenase-2; p < 0.05, nuclear factor kappa B; p < 0.05, tumor necrosis factor-α; p < 0.01, and interleukin-6 (p < 0.01), apoptosis inducers (BCL2-associated X protein; p < 0.05 and Caspase-3 (p < 0.001), and oxidative stress (malondialdehyde; p < 0.05) were considerably reduced with levetiracetam in lipopolysaccharide-induced rats.

Conclusion

The collective results suggested that levetiracetam may be able to treat neuroinflammatory-related memory loss by enhancing cholinergic activity while reducing neuroinflammation, cellular apoptosis, and oxidative stress.

Levetiracetam attenuates diabetes-associated cognitive impairment and microglia polarization by suppressing neuroinflammation

Introduction: Cognitive impairment is a common complication and comorbidity of diabetes. However, the underlying mechanisms of diabetes-associated cognitive dysfunction are currently unclear. M1 microglia secretes pro-inflammatory factors and can be marked by CD16, iNOS, Iba1 and TNF-ɑ. The decline of M2 microglia in the diabetic rats indicates that high glucose promotes the differentiation of microglia into the M1 type to trigger neuroinflammatory responses. Moreover, there is a lack of strong evidence for treatments of diabetes-associated cognitive impairment in addition to controlling blood glucose. Methods: Diabetic rats were established by intraperitoneal injection of one dose of streptozotocin (60 mg/kg). Polarization transitions of microglia were induced by high glucose treatment in BV2 cells. Levetiracetam was orally administered to rats 72 h after streptozotocin injection for 12 weeks. Results: In STZ-induced diabetic rats, the results demonstrated that levetiracetam improved rat cognitive function (Morris water maze test) and hippocampus morphology (Hematoxylin-eosin staining), and the effect was more evident in the high-dose levetiracetam group. Microglia activation in the hippocampus was inhibited by levetiracetam treatment for 12 weeks. Serum levels of TNF-α, IL-1β, and IL-6 were reduced in the LEV-L and LEV-H groups, and IL-1β level was obviously reduced in the LEV-H group. In vitro, we found that levetiracetam 50 µM attenuated high-glucose induced microglial polarization by increasing IL-10 level and decreasing IL-1β and TNF-α levels. Moreover, levetiracetam 50 µM increased and decreased the proportion of CD206+/Iba1+ and iNOS+/Iba1+cells, respectively. Western blot analysis illustrated that LEV 50 µM downregulated the expression of MyD88 and TRAF6, and phosphorylation of TAK1, JNK, p38, and NF-κB p65. The effect of levetiracetam on the anti-polarization and expression of p-JNK and p-NF-κB p65 were partly reversed by anisomycin (p38 and JNK activators). Discussion: Together, our data suggest that levetiracetam attenuates streptozotocin-induced cognitive impairment by suppressing microglia activation. The in vitro findings also indicate that the levetiracetam inhibited the polarization of microglia via the JNK/MAPK/NF-κB signaling pathway.