Effects of feeding on in vivo motility patterns in the proximal intestine of shorthorn sculpin (Myoxocephalus scorpius)

Abstract

Abstract This is the first study to catalogue the diverse array of in vivo motility patterns in a teleost fish and how they are affected by feeding. Video recordings of exteriorised proximal intestine from fasted and fed shorthorn sculpin (Myoxocephalus scorpius) were used to generate spatio-temporal maps to portray and quantify motility patterns. Propagating and non-propagating contractions were observed to occur at different frequencies and durations. The most apparent difference between the feeding states was that bands of relatively high amplitude contractions propagating slowly in the anal direction were observed in all fasted fish (n=10) but only 35% of the fed fish (n=11). Additionally, fed fish displayed a reduced frequency (0.21±0.03 vs. 0.32±0.06 contractions per minute) and rhythmicity of these contractions compared to fasted fish. Although the underlying mechanisms of these slow anally-propagating contractions differ from mammalian MMCs, we believe that they may play a similar role in shorthorn sculpin during the interdigestive period, to potentially remove food remnants and prevent the establishment of pathogens. "Ripples" were the most prevalent contraction type in shorthorn sculpin and may be important during mixing and absorption. Persistence of shallow ripples and pendular movements of longitudinal muscle after TTX (1 µM) treatment suggests these contractions were myogenic in origin. The present study highlights both similarities and differences in motility patterns between shorthorn sculpin and other vertebrates, as well as providing a platform to examine other aspects of gastrointestinal functions in fish, including the impacts of environmental changes.