Reserpine modulates neurotransmitter release to extend lifespan and alleviate age-dependent Aß proteotoxicity in Caenorhabditis elegans.

Aging is a debilitating process often associated with chronic diseases such as diabetes, cardiovascular and neurodegenerative diseases like Alzheimer's disease (AD). AD occurs at a very high incidence posing a huge burden to the society. Model organisms such as C. elegans become essential to understand aging or lifespan extension - the etiology, molecular mechanism and identification of new drugs against age associated diseases. The AD model, manifesting Aß proteotoxicity, in C. elegans is well established and has provided valuable insights. Earlier, we have reported that Reserpine, an FDA-approved antihypertensive drug, increases C. elegans lifespan with a high quality of life and ameliorates Aß toxicity in C. elegans. But reserpine does not seem to act through the known lifespan extension pathways or inhibition of its known target, vesicular monoamine transporter, VMAT. Reserpine's mode of action and the pathways it activates are not known. Here, we have evaluated the presynaptic neurotransmitter(s) release pathway and identified acetylcholine (ACh) as the crucial player for reserpine's action. The corroborating evidences are: i) lack of lifespan extension in the ACh loss of function (hypomorphic) - synthesis (cha-1) and transport (unc-17) mutants; ii) mitigation of chronic aldicarb effect; iii) lifespan extension in dopamine (cat-2) and dopamine and serotonin (bas-1) biosynthetic mutants; iv) no rescue from exogenous serotonin induced paralysis in the AD model worms; upon reserpine treatment. Thus, modulation of acetylcholine is essential for reserpine's action.

ALS associated mutant SOD1 impairs the motor neurons and astrocytes and wild type astrocyte secreted-factors reverse the impaired motor neurons.

BACKGROUND: Amyotrophic Lateral Sclerosis, in which motor neurons degenerate, leading to paralysis, not only the affected motor neurons, but the surrounding non-neuronal cells also contribute significantly to the disease. However, the disease mechanism is not known. PURPOSE: In this study we have addressed the disease mechanism by expressing the ALS associated mutant SOD1(G37R) in the motor neurons (mMN) and astrocytes (mA) cell lines. METHODS: A series of cell culture assays, immunostaining, RT-PCR and Western blot analysis were performed. RESULTS: We noticed impairments in both these cell types. The mMN motor neurons were insensitive to forskolin, a known activator of adenylate cyclase, which leads to motor neuron death. In addition, less number of mMN were positive for phosphorylated neurofilament-H (pNFH) unlike the normal motor neurons. Similarly, the mutant SOD1 expressing astrocytes (mA) had two impairments: The inability to activate the oxidative stress protection and the absence of secretory factor(s). Normal astrocytes and their secreted factors could restore the pNFH in the mMN but not the mA. In addition, we show that pNFH restoration is a specific function since the insensitivity of mMN to forskolin could be rescued by neither normal astrocytes nor their secreted factors. CONCLUSION: Thus we demonstrate some of the abnormalities caused by the ALS associated mutant SOD1(G37R) and a potential way, to reverse an abnormality through cell replacement.

Reserpine ameliorates Abeta toxicity in the Alzheimer's disease model in Caenorhabditis elegans.

Earlier we have reported that reserpine, an antihypertensive drug, known to downregulate biogenic amines through inhibition of the vesicular monoamine transporter (VMAT), increases longevity of Caenorhabditis elegans with a high quality of life, namely, enhanced and prolonged mobility (Srivastava et al., 2008). As neurodegenerative diseases are of adult onset, we addressed the protective ability of reserpine against neurodegenerative diseases, especially Alzheimer's disease (AD). In the well established AD model in C. elegans, Amyloid beta (Abeta) is expressed in the muscles and Abeta toxicity is manifested as paralysis (Link, 1995). In this model, reserpine significantly delayed paralysis and increased the longevity. In addition, reserpine provided thermotolerance, but interestingly the Abeta transcript and expression levels remains grossly unchanged.

Reserpine can confer stress tolerance and lifespan extension in the nematode C. elegans.

Though the lifespan extension mechanism is partly understood from C. elegans to mice, a viable pharmacological intervention is not yet feasible. Here, we report that reserpine largely known as an antipsychotic-antihypertensive drug, can extend C. elegans lifespan. Chronic reserpine treatment from embryo stage or young adults extends the C. elegans lifespan robustly at 25 degrees C. Most importantly, the reserpine treated long lived worms are active (locomotion and pharyngeal pumping) for a long time thereby conferring high quality throughout life. Reserpine mediated lifespan extension is independent of the daf-16 pathway and partly requires serotonin. Reserpine treatment makes the worms highly thermotolerant. Thus, in addition to its known function, reserpine is able to provide stress tolerance and lifespan extension in C. elegans.