Abstract

AN OVERVIEW OF THE METHODS USED IN PRECLINICAL EVALUATION OF NOOTROPIC AGENTS: A SYSTEMIC REVIEW

Joly Asmaul Hossna, Sreemoy Kanti Das* and Nadiah Syafiqah Binti Nor Azman

ABSTRACT

Smart medicines, memory enhancers, and cognitive enhancers are other names for nootropics. It has been reported that they enhance mental abilities like intelligence, motivation, memory, focus, and concentration. It is believed that they function by changing the availability of neurochemicals in the brain, enhancing the oxygen flow to the brain, or promoting the creation of new nerve cells. The most frequent cause of dementia is Alzheimer's disease (AD), a progressive neurodegenerative condition that primarily affects the elderly. It could get to the point of complete vegetative state. Neurofibrillary tangles and the deposition of β-amyloid protein in the form of senile plaques are linked to atrophy of cortical and sub-cortical areas. The brain exhibits a substantial cholinergic deficit, but other Systems of neurotransmitters are also impacted. There have been several attempts to increase cholinergic transmitter levels in the brain. Clinical usage of the comparatively cerebroselective anti-ChEs has been approved. Numerous screening models are accessible for the preclinical assessment of nootropic medications. Newer models are developed in accordance with limitations of the earlier one. In-vitro methods inhibition of acetylcholinesterase activity is measured by determining IC50 with the help of Log probit analysis. In ex-vivo cholinesterase inhibition method the dose response relationship determined for drugs such as physostigmine and tacrine. Studies on molecular form of AchEs are carried in rat frontal cortex and striatum for drug such as donepezil, tacrine. Agents which are H3 receptor agonist are evaluated for [3H] Ach release activity in rat using rat brain slices. The binding affinity of potential nicotinic cholinergic agonist in brain using agonist ligand is determined by [3H]-N- methyl carbamylcholine binding nicotinic cholinergic receptors in rat frontal cortex. In In-vivo methods the inhibitory passive avoidance the test are carried on animals to test the learning and memory capacity of animal by suppressing a particular behavior. It includes step down, step through, two compartment test, up-hill avoidance, scopolamine induced test, and ischemia induced amnesia, memory impairments in basal forebrain.

Keywords: Nootropic agents, animal models, cognition, etiology, vascular dementia, Alzheimer's disease.