INTRODUCTION
Traumatic brain injury is a global health concern. It is an unexpected
diversified condition for most enervative consequences like
post-traumatic epilepsy. TBI is the foremost reason for death worldwide
and disability in the youths, sportspersons, and army veterans. It has
been estimated that nearly 69 million population worldwide get brain
insult annually(James et al., 2019; Maas et al., 2008) but in India,
road traffic injuries cost 60% of total TBI cases(Gururaj, 2008; Murray
& Lopez, 1996). Brain trauma in the general population, reports 20% of
symptomatic epilepsy and 5% of all epilepsy(Immonen et al., 2019).
Primary brain insult confirms brain hemorrhage, an increase in
intracranial pressure, and cellular swelling which results in brain
edema and blood-brain barrier damage. The cerebral bruises and tissue
damage, complicate the secondary cascade by exacerbating neuronal
inflammation and mitochondrial ETC dysfunction(Chen et al., 2021).
Activated immune cells of inflamed sites initiate other catastrophic
mechanisms by overproduction of proteases, ROS/RNS, and NF-κβ that
interfere with the expressions of different inflammatory markers and
pro-inflammatory cytokines(Shao et al., 2021). This pathophysiology
counted for the progression of the epileptogenesis cascade which lowers
down the seizure threshold of the injured brain and gives the first
post-traumatic successive seizure(Pitkänen et al., 2007).
Fluid Percussion Injury and Cortical Compact Injury studies were
performed on mice models of brain trauma and they have detected
increased seizure susceptibility for sub convulsive doses of
pentylenetetrazole (i.e. non-convulsant at 35mg/kg)(Mukherjee et al.,
2013). Disturbed Na+ and Ca2+ influx
through Transient Receptor Potential Melastatin-2 (TRPM2) channels prop
up membrane depolarization, induce production of prostaglandins, disrupt
the mitochondrial and endoplasmic reticulum functions which further led
to enhance the intracellular Ca2+ through TRPM2
channels(Perraud et al., 2001). Rho signaling pathway was found highly
activated in brain injuries due to inflammation and injury in the
neuronal cytoskeleton(Brabeck et al., 2004). Inflammatory markers like
TNF-α and glutamate also contribute to early cell death following
TBI, by activating Rho kinases
i.e. Rho-associated Protein Kinase (ROCK2)(Neumann et al., 2002). An
experimental rat model of weight drop injury produces a diffuse type of
injury by mimicking clinical complication and its complex
pathophysiology provide post-traumatic complications(Chandel et al.,
2016; Ye Xiong et al., 2013).
FDA-approved anti-seizure therapies include Valproic Acid,
carbamazepine, lamotrigine, phenytoin but we still lack
anti-epileptogenic therapy(Romoli et al., 2018). It was investigated
that valproic acid influences rat hippocampus for the levels of
glutamate and GABA transporter proteins during epileptogenesis(Ueda &
Willmore, 2000). Flufenamic Acid belongs to the fenamate class of
Non-Steroidal Anti-Inflammatory Drug, COX enzyme inhibition, and TRPM2
channel blocker which was found neuroprotective in in-vitrostudies(Khansari & Coyne, 2012). Fasudil Hydrochloride is a selective
ROCK2 inhibitor that induces neuroprotection in-vitro and also a
specific inhibitor of NF-κB and protects against axonal degeneration and
neuronal apoptosis(Fujimura et al., 2011; Xiao et al., 2014). The
altered TBI pathophysiology is described in figure-1.
So, this study hypothesized that the recruitment of
Ca2+ antagonists, TRPM2 channel blockers, and ROCK2
inhibitors might be effective for the initiation of neuroprotective
responses after initial brain insult to stop or minimize the activated
TBI associated epileptogenesis consequences. Hence this study was aimed
to explore the in-vivo effects, efficacy, and potential of
flufenamic acid and fasudil hydrochloride for the treatment of TBI
induced epileptogenesis in experimental weight drop injury model of TBI.