OxiracetamvsPiracetam

Oxiracetam enhances glutamatergic neurotransmission through positive allosteric modulation of AMPA receptors, increasing the amplitude and duration of excitatory postsynaptic potentials. It increases the release of excitatory neurotransmitters glutamate and D-aspartic acid from hippocampal presynaptic terminals, acting as a glutamate analog. Oxiracetam stimulates protein kinase C (PKC) isoforms, particularly PKC-α and PKC-γ, which phosphorylate substrates involved in memory consolidation, long-term potentiation (LTP), and synaptic plasticity. PKC activation enhances NMDA receptor function and AMPA receptor trafficking to the synapse. Its mild stimulatory effect derives from cholinergic system enhancement via increased acetylcholine release and nicotinic α7 receptor potentiation in the cortex.

Piracetam modulates AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and NMDA (N-methyl-D-aspartate) glutamate receptors through positive allosteric modulation, enhancing excitatory neurotransmission without direct agonism. It increases membrane fluidity of neuronal phospholipid bilayers by reducing membrane microviscosity, which improves ion channel function and signal transmission. Piracetam enhances acetylcholine receptor density and turnover in the hippocampus, upregulating both muscarinic (M1) and nicotinic receptor expression. It potentiates the cholinergic system through increased high-affinity choline uptake. Additionally, piracetam improves cerebral blood flow via nitric oxide-dependent vasodilation and enhances oxygen utilization (glucose metabolism) in aged or hypoxic brain tissue, supporting mitochondrial function.