Is the renin-angiotensin system a friend or foe in neurological diseases? Unveiling its role and therapeutic potential

The renin-angiotensin system (RAS), an important regulator of body fluid and cardiovascular homeostasis, is gradually implicated in the pathogenesis of neurological diseases due to its dysregulation. In addition to their traditional functions, components of the RAS, especially angiotensin-II (Ang-II), enhance neuroinflammation, oxidative stress, and neuronal injury. Ang-II exacerbates blood-brain barrier (BBB) disruption, promotes glial activation, and contributes to neurodegeneration via the Angiotensin type 1 (AT1) receptor (AT1R) and causes neurological diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), Huntington’s disease (HD), epilepsy, depression, and anxiety. The angiotensin (1−7) axis mediated by the Mas receptor appears to be neuroprotective, however, as it reverses the negative effects of Ang-II. In experimental models and clinical trials, blocking RAS specifically by angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) has demonstrated promise in reducing neuroinflammation and neuronal damage, especially in stroke and neurodegenerative diseases. In the current era of research, neuropharmacologists have new optimism due to emerging evidence of the promising potential of RAS-modulating drugs, such as ARBs and ACEIs, in the treatment of various neurological diseases. Since RAS imbalance causes neuroinflammation, neuronal damage, and cognitive decline in conditions including AD, PD, and MS, these drugs may offer a new treatment approach. In the current era of neuropharmacology, this technique is novel since it enables more targeted therapies to address the root causes of neurodegeneration. This review explores the molecular pathways of RAS dysregulation in various neurological diseases, highlighting its therapeutic potential and paving the way for future treatment strategies.