Reserpine requires the D2-type receptor, dop-3, and the exoribonuclease, eri-1, to extend the lifespan in C. elegans.

Lifespan extension is an all systems encompassing event. Involvement of reduced insulin/IGF1 signalling is well worked out, first in the model organism Caenorhbaditis elegans followed by other systems including humans. But the role of neuronal component in lifespan extension is not well understood due to the refractory nature of neurons to small RNA interference (sRNAi) in C. elegans. Earlier, we have demonstrated that an antihypertensive drug, reserpine, extends lifespan through modulation of neurotransmitter release, especially, acetylcholine, in C. elegans. Intriguingly, the reserpine mediated lifespan extension (RMLE) does not happen through the known longevity pathways. Here, we report that the D2-type dopamine receptor (DOP-3), which acts through the inhibitory Gprotein coupled (G alpha i) pathway mediated signalling is partly required for RMLE. In the dop-3 loss of function mutant RMLE is shortened. DOP-3 acts through Gαo (goa-1). One of the downstream targets of G protein signalling is the transcription factor, jun-1. MRP-1, an ATP binding cassette transporter, belonging to the multidrug resistance protein family is one of the genes turned on by JUN-1. RMLE is shortened in dop-3-->goa-1-->jun1-->mrp-1 loss of function mutants, elucidating the contribution of dop-3 signalling. The dop-3 receptor system is known to inhibit acetylcholine release. This suggests dopamine receptor, dop-3 could be contributing to the modulation of acetylcholine release by reserpine. ERI-1 is a 3'-5' exoribonuclease, one of the negative regulators of sRNAi, whose loss of function makes neurons amenable to siRNA. In the absence of eri-1, RMLE is shortened. In the dop-3 loss-of-function background, lack of eri-1 completely abolishes RMLE. This suggests that dop-3 and eri-1 act in independent parallel pathways for RMLE and these two pathways are essential and sufficient for the longevity enhancement by reserpine in C. elegans.

A Novel Way of Amelioration of Amyloid Beta Induced Toxicity in Caenorhabditis elegans.

BACKGROUND: With an incidence of 1 in 85 persons above the age of 60 years succumbing to the disease, Alzheimer's disease (AD), has been predicted to create havoc globally. In spite of enormous efforts and exhaustive research, no cure is in sight. Hence, it is critical to unravel the mechanism of AD development/protection and identification of a cure soon. PURPOSE: This study is aimed at investigating the mechanism of reserpine action, which alleviates the toxicity of amyloid beta (Aß) (AD-causing peptide) in Caenorhabditis elegans [1, 2]. METHODS: Determination of alleviation of Aß toxicity with reserpine manifested as reduction in progressive paralysis, in the background of GFP reporter driven by the promoter of the FMRFamide neuropeptide, FLP-11 (AD; Pflp-11::GFP) and acetylcholine contribution through aldicarb (which inhibits acetylcholine esterase) treatment. RESULTS: The most significant protection against Aß toxicity was obtained in the background of Pflp-11::GFP. This protection had 2 components. The promoter of FLP-11 with the reporter GFP, Pflp-11::GFP, per se gave significant protection. Further reserpine treatment provided additional alleviation. Together they could almost eliminate Aß toxicity. These 2 components of Aß toxicity alleviation are dependent on acetylcholine levels, as an increase in acetylcholine by aldicarb treatment reduces the protective effect. CONCLUSION: A unique way to alleviate Aß toxicity is reserpine treatment in combination with Pflp-11::GFP. Reserpine should be evaluated as a potential drug in a pilot study in AD patients. Furthermore, identification of the mechanism of Pflp-11::GFP-mediated reduction in Aß toxicity is a potential pathway to develop therapeutics for AD.

Withania somnifera root extract extends lifespan of Caenorhabditis elegans.

BACKGROUND: In the ancient Indian herbal medicine system several ayurvedic preparations are claimed to have longevity enhancing effects. But, so far, no clear scientific evidence has been provided. One among them, is the roots of the plant, commonly known as Ashwagandha (Withania somnifera Dunal- WSD), which is supposed to have myriad of beneficial effects including long life. PURPOSE: Here, we evaluated both the root extract (RE) and its purified ingredients (PI-RE) with a similar composition as in RE obtained from the roots of WSD for lifespan extension in the well established model system, C. elegans. PI-RE could extend the lifespan of C. elegans. METHODS: We used wild type C. elegans (N2) or RB918: acr-16 (ok789); andNL2099: rrf-3 (pk1426) mutant worms and analysed their lifespan assay in Ashwagandha extract spreaded on plates containing Bacterial Lawns. RESULTS: Strangely, while there was no effect on the wild type worms, the mutant for the human nicotinic acetylcholine receptor, nAchR, α7 equivalent, acr-16, showed around ~20% lifespan extension when treated with PI-RE. CONCLUSION: Thus, we are able to show that one of the age old healthy longlife supplements, Ashwagandha does extend lifespan of C. elegans.

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.