Antony Justin

By J. Jeyaram Bharathi and Justin Antony

Cognitive impairment and dementia are the most frequently occurring nonmotor symptoms in Parkinson’s disease (PD), yet these symptoms are mostly overlooked and are not diagnosed and treated exceptionally like the cardinal motor symptoms in clinical practice. It is only in the late twentieth century that dementia has been recognized as a major clinical manifestation in PD. The possible mechanisms that cause dementia are complex with different patterns of cognitive behavior that disrupt the patient’s quality of life. It is preeminently considered that the cholinergic denervation in the basal forebrain region mediates dementia in PD. So far, dopamine-based therapy is the key objective in the treatment of PD and the nonmotor symptoms are mostly neglected. Interestingly, the loss of Tyrosine kinase receptor-A (TrkA) signaling in basal forebrain results in neuronal atrophy, which precedes cholinergic denervation and cognitive impairment. Nerve Growth Factor (NGF) binds to TrkA receptors, inducing a cascade of events like PI-3Kinase/Akt and MAPK signaling pathways that render cholinergic degeneration and upregulate the choline acetyltransferase activity and neuronal differentiation. Hence, TrkA receptor activation by small molecules might attenuate the dementia symptoms associated with PD, and may be targeted as a novel treatment strategy along with regular clinical agents.

Part of the book: Dementia in Parkinson’s Disease

By Sayani Banerjee, Chennu Manisha, Deepthi Murugan and Antony Justin

Gamma-amino butyric acid (GABA) is a major inhibitory neurotransmitter found in several regions of the brain and known to have various significant physiological roles as a potent bioactive compound. Malfunction of GABAergic neuronal signaling prompts to cause severe psychiatric symptoms in numerous mental disorders. Several drugs are available in clinical practice for neuropsychiatric disorders targeting through GABAergic pathway, with notable adverse effects. Interestingly, in recent years, researchers are focusing on natural compounds altering GABAergic neurotransmission for various psychiatric disorders due to its wide range of therapeutic efficacy and safety. The enormous variety of natural compounds, namely alkaloids, flavonoids, terpenoids, polyacetylenic alcohols, alkanes and fatty acids were reported to alter the GABAergic transmission through its receptors and or by influencing the transmission, synthesis and metabolism of GABA. Natural compounds are able to cross the blood brain barrier and influence the GABA functions in order to treat anxiety, mania, schizophrenia and cognitive disorders. Therefore, this current chapter describes on natural products which have the potential to alter the GABAergic neurotransmission and its therapeutical benefits in treating several neuropsychiatry disorders using various pharmacological methods.

Part of the book: Natural Medicinal Plants