By Rideeta Raquib ’19

The central nervous system is essential in regulating different parts of the body. Serotonin (5-hydroxytryptamine, 5-HT), a neuromodulator, has been related to feeding and metabolizing, as well as burning fat. Biologists at the Scripps Research Institute set out to identify a neuropeptide ligand and its cognate receptor that makes up the 5-HT neuroendocrine axis. The study was conducted on a roundworm species called C. elegans that have primitive but similar signaling molecules as human beings.

In order to understand the neuroendocrine signal, the extent to which serotonin-mediated fat loss being dependent on the release of canonical neurotransmitters, such as acetylcholine γ-amino butyric acid, and glutamate, was measured. These neurotransmitters require the protein, UNC-13 (MUNC-13 for mammals) in order to fuse with the plasma membrane at the synaptic vesicle. The results showed that vesicle-treated UNC-13 mutants were similar to wild-type animals, but the MUNC-31 mutants had double the body fat. This suggests that the vesicles from the nervous system regulate fat storage. Likewise, a neuropeptide gene, called flp-7, led to a decrease in body fat reserves which may also promote body fat loss. Overall, flp-7 was expressed in several head neurons and completely restored 5-HT-induced fat loss in the intestines.

MUNC-31 and flp-7 are mechanisms that can regulate the release of synaptic vesicles. Future research should study the additional factors that regulate the release of core vesicles to advance findings in neuromodulation and neuroendocrine biology.

References:

1. L. Palamiuc, et al., A tachykinin-like neuroendocrine signalling axis couples central serotonin action and nutrient sensing with peripheral lipid metabolism. Nature Communications (2017). doi: 10.1038/ncomms14237.
2. Image retreived from: http://images.wisegeek.com/neural-network-of-brain.jpg