Normalization of Calcium Balance in Striatal Neurons in Huntington's Disease: Sigma 1 Receptor as a Potential Target for Therapy

Neuroprotective effect of silymarin against 3-Nitropropionic acid-induced neurotoxicity in rats

(HD) Huntington's disease is a severe hereditary catastrophic neurological disease with an autosomal dominant heritable changes manifested by cognitive, behavioural, and motor progression deficits, resulting in death. Several mechanisms are involved in the pathogenesis of this complex and rare disease, including excitotoxicity, mitochondrial dysfunction, neurotransmitters imbalance, and oxidative stress. Silymarin was selected as an investigational drug, due to its numerous activities in current research, it possesses substantial antioxidant and neuroprotective functionalities. The present research attempts, i.p. injections of 3-NPA (10 ​mg/kg) were given for 21 days to trigger Huntington-like symptoms in rats. The percentage fluctuations in body weight, the footfall counts, and the time required to transverse the beam and motor functions were analyzed at multiple time points. Oxidative stress markers like MDA/LPO, GSH, protein, nitrite, catalase, and superoxide dismutase levels were examined in the striatum region. The current study results conclusively demonstrate that chronic 3-NPA administration significantly decreased the body weight and showed marked abnormalities in motor coordination, locomotion, and increased striatal generation of free radicals. Furthermore, treatment with silymarin (100 & 200 ​mg/kg/p.o.), mitigated 3-NPA triggered behavioural and biochemical alterations. Our study results could conclude that Silymarin may be advantageous and might develop an adjuvant treatment for the management of Huntington's disease.

Novel Therapeutic Target for Prevention of Neurodegenerative Diseases: Modulation of Neuroinflammation with Sig-1R Ligands

Neurodegenerative diseases (NDDs) are characterized by progressive deterioration of the structure and function of cells and their networks in the nervous system. There are currently no drugs or other treatments that can stop the progression of NDDs. NDDs have many similarities and common pathways, e.g., formation of misfolded amyloid proteins, intra- and extracellular amyloid deposits, and chronic inflammation. Initially, the inflammation process has a cytoprotective function; however, an elevated and prolonged immune response has damaging effects and causes cell death. Neuroinflammation has been a target of drug development for treating and curing NDDs. Treatment of different NDDs with non-steroid anti-inflammatory drugs (NSAIDs) has failed or has given inconsistent results. The use of NSAIDs in diagnosed Alzheimer's disease is currently not recommended. Sigma-1 receptor (Sig-1R) is a novel target for NDD drug development. Sig-1R plays a key role in cellular stress signaling, and it regulates endoplasmic reticulum stress and unfolded protein response. Activation of Sig-1R provides neuroprotection in cell cultures and animal studies. Clinical trials demonstrated that several Sig-1R agonists (pridopidine, ANAVEX3-71, fluvoxamine, dextrometorphan) and their combinations have a neuroprotective effect and slow down the progression of distinct NDDs.

Connection Lost, MAM: Errors in ER-Mitochondria Connections in Neurodegenerative Diseases

Mitochondria associated membranes (MAMs), as the name suggests, are the membranes that physically and biochemically connect mitochondria with endoplasmic reticulum. MAMs not only structurally but also functionally connect these two important organelles within the cell which were previously thought to exist independently. There are multiple points of communication between ER-mitochondria and MAMs play an important role in both ER and mitochondria functions such as Ca²⁺ homeostasis, proteostasis, mitochondrial bioenergetics, movement, and mitophagy. The number of disease-related proteins and genes being associated with MAMs has been continually on the rise since its discovery. There is an overwhelming overlap between the biochemical functions of MAMs and processes affected in neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Thus, MAMs have received well-deserving and much delayed attention as modulators for ER-mitochondria communication and function. This review briefly discusses the recent progress made in this now fast developing field full of promise for very exciting future therapeutic discoveries.