Centella asiactica: acute effects on daphnia magna.
Centella asiactica: acute effects on daphnia magna. Ronald n. Hunsinger and Suzanne D. Oberholster. Department of Biological and Environmental Sciences. Samford University, Birmingham, AL, 35229.
Exposure of Daphnia magna to 1.0 ppm Centella asiactica (CeA) leaves pulverized in distilled water resulted in a dramatic increase, approximately 3-fold, in locomotor activity as determined by swimming activity in a gridded test apparatus. In this trial, no algae were provided as a food source during the 24-hr pre-test exposure period. When algae were provided during the exposure period in subsequent experiments, locomotor activity was still increased 3-fold during the test trials. The results of these assays suggest that the increased locomotor activity seen as a result of CeA exposure did not result from the CeA acting just as a food source, providing an energy supply. Locomotor activity was also increased with CAST exposure. CAST refers to a mixture of selected triterpenes believed to be the active ingredient in CeA. CeA and CAST also modified the normally negative phototaxic response seen in daphnids. Daphnids usually display a negative phototaxic response, which is believed to be a defense tactic by the organism, allowing retreat into darker, less vulnerable environments. Heart rates in treated daphnids (CeA and CAST) were significantly increased. While CeA and its active ingredient, CAST, greatly stimulated locomotor activity blunted the negative phototaxic response and increased heart rates in daphnids, the mechanisms of these effects are not known. Although locomotor activity was increased following exposure of daphnids incubated with and without algae as a food source, it is not clear whether the effects are neuronal or metabolic. However, the loss of some negative phototaxic behavior in organisms exposed to CeA and CAST suggests a neuronal basis. Little is known about the nervous system of Daphnia. There is a protocerebrum, connecting to the compound eye and other frontal filaments and organs, a deuto- and trito-cerebrum, which receive input from antennae and a ventral nerve cord ganglial network. However, little is known about neurotransmitters involved with these structures. An elegant study by McCoole et al. (2011), did implicate histaminergic signaling in the nervous system related to phototaxic behavior. In conclusion, CeA and CAST do exert similar behavioral effects in an invertebrate model as seen in mammalian models. These findings, while not definitive as to mechanisms, do demonstrate that CeA and its ingredients exert powerful biological actions which reflect the claims of proponents of the plant as an herbal extract and the neuropharmacological findings in mammalian models.
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|Title Annotation:||Biological Sciences Poster Abstracts|
|Publication:||Journal of the Alabama Academy of Science|
|Date:||Apr 1, 2014|
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