Related Experiment Video
Updated: Aug 6, 2025
Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome
Published on: June 10, 2013
Apigenin Attenuates Hippocampal Microglial Activation and Restores Cognitive Function in Methotrexate-Treated Rats:
Mohamed Taha1, Omar Mohsen Eldemerdash2, Ismail Mohamed Elshaffei2
1Department of Biochemistry, Faculty of Pharmacy, Cairo University, Kasr El Ainy st., Cairo, 11562, Egypt. mohamed.taha@pharma.cu.edu.eg.
Abstract:
Microglial activation underpins the methotrexate (MTX)-induced neurotoxicity; however, the precise mechanism remains unclear. This study appraised the potential impact of apigenin (Api), a neuroprotective flavonoid, in MTX-induced neurotoxicity in rats in terms of microglial activation through targeting the miR-15a/Rho-associated protein kinase-1 (ROCK-1)/extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Male Sprague Dawley rats were randomly divided into 4 groups: Normal control (saline i.p. daily and i.v. on days 8 and 15); Api control (20 mg/kg, p.o.) daily for 30 days; MTX-alone (75 mg/kg, i.v.) on days 8 and 15, then four i.p. injections of leucovorin (LCV): 6 mg/kg after 18 h, then three doses (3 mg/kg) every 8 h post-MTX; and Api co-treated (20 mg/kg/day, p.o.) throughout the model for 30 days, with administration of MTX and LCV as in group 3. MTX administration elevated hippocampal ionized calcium-binding adaptor protein-1 (Iba-1) immunostaining, indicating microglial activation. This was accompanied by neuroinflammation, oxidative stress, and enhanced apoptosis manifested by elevated hippocampal interleukin-1β, malondialdehyde, and caspase-3, and decreased reduced glutathione levels. Concurrently, abated miR-15a expression, overexpression of its target ROCK-1, diminished downstream ERK1/2 and cAMP response element-binding protein (CREB) phosphorylation, and decreased hippocampal brain-derived neurotrophic factor (BDNF) levels were observed. Api mitigated the MTX-induced neurotoxicity by reversing the biochemical, histopathological, and behavioral derangements tested by novel object recognition and Morris water maze tests. Conclusively, Api lessens MTX-induced neuroinflammation, oxidative stress, and apoptosis and boosts cognitive function through inhibiting microglial activation via modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway. Graphical abstract showing the effects of methotrexate and apigenin co-treatment in MTX-induced neurotoxicity model. On the left, methotrexate (MTX) administration to rats resulted in hippocampal miR-15a downregulation, which triggered an enhanced expression of its target ROCK-1, consequently inhibiting the downstream ERK1/2/CREB/BDNF pathway, instigating a state of microglial activation, neuroinflammation, oxidative stress, and apoptosis. On the other hand, apigenin (Api) co-treatment restored miR-15a, inhibited ROCK-1 expression, and activated the ERK1/2/CREB/BDNF pathway, leading to diminished hippocampal microglial activation, neuroinflammation, and apoptosis, and restoration of the redox balance, along with improvement in memory and cognitive function of the MTX-treated rats.
Insights
Apigenin (Api) protects against methotrexate (MTX)-induced neurotoxicity by reducing microglial activation and neuroinflammation. This neuroprotective flavonoid targets the miR-15a/ROCK-1/ERK1/2 pathway, improving cognitive function in rats.
Area of Science:
- Neuroscience
- Pharmacology
- Toxicology
Background:
- Methotrexate (MTX) causes neurotoxicity, with microglial activation playing a key role, but the exact mechanism is not fully understood.
- Apigenin (Api) is a flavonoid with known neuroprotective properties.
- Understanding the molecular pathways involved in MTX neurotoxicity is crucial for developing effective interventions.
Purpose of the Study:
- To investigate the protective effects of apigenin (Api) against methotrexate (MTX)-induced neurotoxicity in a rat model.
- To elucidate the underlying mechanism involving microglial activation via the miR-15a/ROCK-1/ERK1/2 pathway.
- To assess the impact of Api on neuroinflammation, oxidative stress, apoptosis, and cognitive function.
Main Methods:
- Male Sprague Dawley rats were divided into four groups: control, Api control, MTX-alone, and Api co-treated.
- MTX was administered intravenously, with leucovorin (LCV) rescue; Api was given orally daily.
- Neurotoxicity was assessed by measuring microglial activation (Iba-1), neuroinflammation (IL-1β), oxidative stress (MDA, GSH), apoptosis (caspase-3), and cognitive function (novel object recognition, Morris water maze).
Main Results:
- MTX administration increased microglial activation, neuroinflammation, oxidative stress, and apoptosis in the hippocampus.
- MTX treatment led to decreased miR-15a expression, increased ROCK-1, reduced ERK1/2/CREB phosphorylation, and lower BDNF levels.
- Apigenin co-treatment reversed these MTX-induced changes, mitigating neurotoxicity and improving cognitive performance.
Conclusions:
- Apigenin effectively lessens MTX-induced neuroinflammation, oxidative stress, and apoptosis, thereby protecting against neurotoxicity.
- Api exerts its neuroprotective effects by inhibiting microglial activation through the modulation of the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway.
- Apigenin co-treatment offers a promising therapeutic strategy to counteract MTX-induced cognitive deficits and neurotoxic effects.
