Natalia N. Morales-Pagán, Solymar Rolón-Martínez, Lee O. Vaasjo, Alana Rivera-Dominguez, Dina P. Bracho-Rincón, and Mark W. Miller
1 Institute of Neurobiology and 2 Department of Anatomy & Neurobiology, University of Puerto Rico, Medical Science Campus, San Juan, Puerto Rico

Introduction: Schistosomiasis is a parasitic disease caused by the trematode worm Schistosoma mansoni. It is the third most reported tropical disease, affecting 250 million people worldwide. By studying the freshwater snail Biomphalaria glabrata, the parasite’s primary intermediate host in the Western Hemisphere, we can learn how infection may affect snail behavior by altering neuropeptide expression. In gastropods, neuropeptide Y (NPY) regulates various physiological processes such as food intake, reproduction, and growth. Due to its pleiotropic functions, NPY is one target candidate for developing a strategy for snail control. We hypothesize that NPY expression will be decreased in infected snails, leading to increased food consumption to meet the parasites’ energy requirements.

Methods: Double-labeling experiments were done using the Hybridization Chain Reaction method (HCR; Molecular Instruments, LA CA) and Immunohistochemistry.

Results: NPY-like immunoreactive (NPYli) neurons were detected in the central ganglia. In the digestive system, 10-20 possible NPYli neurons were present on the distal esophagus, near its border with the triturating stomach. We propose that these cells provide feedback to the CNS regarding gut distension. NPYli innervation was also observed in the reproductive organs (sperm duct and prostate).

Conclusion: Localization of NPY mRNA, detected using the Hybridization Chain Reaction method, agreed with our immunohistochemical observations. Future studies will test the hypothesis that BgNPY neurons on the distal esophagus transmit satiety signals to the central feeding motor system, and that down-regulation of these signals contributes to increased feeding in infected snails.

Acknowledgements: Supported by the U.S. National Institutes of Health MD007600 (RCMI; MWM), GM103642 (COBRE; MWM, DBP-R), GM007821 (MARC; MRC); the U.S. National Science Foundation HRD-736019 (MWM), OISE-1545803 (MWM), DBI-1337284 (MWM) and IOS- 2217657 (MWM); the U.S. National Academy of Sciences, Engineering, and Medicine (NASEM) U.S.-Egypt Science and Technology Joint Fund 2000007152* (MWM), and the Egyptian Science and Technology Development Fund USC17-188 (STDF; MRH). Reagents were provided by the Schistosomiasis Resource Center of the Biomedical Research Institute (Rockville, MD) through NIH-NIAID Contract HHSN272201700014I: Biomphalaria glabrata (NMRI) exposed to Schistosoma mansoni (NMRI).

Keywords: NPY, Schistosoma mansoni, snail fever, hybridization chain reaction, esophagus