The crustacean stomatogastric
ganglion (STG) is a valuable model for understanding circuit dynamics in neuroscience as it contains a small number of neurons, all easily distinguishable and most of which contribute to two complementary feeding-related neural circuits. These circuits are modulated by numerous
neuropeptides, with many gaining access to the STG as hemolymph-transported
hormones. Previous work characterized
neuropeptides in the hemolymph of the crab
Cancer borealis but was limited by low
peptide abundance in the presence of a complex biological matrix and the propensity for rapid
peptide degradation. To improve their detection, a data-independent acquisition (
DIA) mass spectrometry (MS) method was implemented. This approach improved the number of
neuropeptides detected by approximately twofold and showed greater reproducibility between experimental and biological replicates. This method was then used to profile
neuropeptides at different stages of the feeding process, including hemolymph from crabs that were unfed, or 0 min, 15 min, 1 h, and 2 h post-feeding. The results show differences both in the presence and relative abundance of
neuropeptides at the various time points. Additionally, 96 putative
neuropeptide sequences were identified with de novo sequencing, indicating there may be more key modulators within this system than is currently known. These results suggest that a distinct cohort of
neuropeptides provides modulation to the STG at different times in the feeding process, providing groundwork for targeted follow-up electrophysiological studies to better understand the functional role of circulating
hormones in the neural basis of feeding behavior.