Magee, K. | Search bioRxiv

bioRxiv2026

Profile of the digestive and absorptive functions in the intestine of fish with different dietary habits and in response to increased dietary carbohydrate or protein.

Global aquaculture has grown significantly, but to maintain current consumption, supply must double over the next 20 years. Here, we characterised the digestive and absorptive capacities in the intestines of three commercially important, farmed fish species with varying natural diets: Nile tilapia (Oreochromis niloticus), common carp (Cyprinus carpio ), and rainbow trout (Oncorhynchus mykiss). Disaccharidase activity (maltase, sucrase) and sodium-dependent D-glucose absorption were highest in Nile tilapia, followed by common carp, and lowest in rainbow trout. We found regional intestinal differences in disaccharidase activity and SGLT1 expression in the three species. Aminopeptidase A (APA) and aminopeptidase N (APN) activities were typically highest in Nile tilapia. Intestinal expression of the neutral amino acid transporter B0AT1 was approx. double in tilapia and carp compared to trout. We also assessed common carp, zebrafish and Rainbow trout's digestion profile when fed low-carbohydrate/high protein and high-carbohydrate/low-protein diets. Common carp and zebrafish adapted to high-carbohydrate diets by up-regulating both digestive enzymes and SGLT1. Common carp increased SGLT1 protein abundance 2.7-fold in the foregut and 4.6-fold in the hindgut. Rainbow trout increased disaccharidase activity but not SGLT1 expression in response to a high-carbohydrate diet. Both Rainbow trout and common carp down-regulated their APN activity but upregulated their B0AT1 expression 2-fold in response to increased dietary protein. These physiological limitations are critical considerations for formulating sustainable plant-based aquafeeds.

physiology↗

bioRxiv2020

Neuroskeletal effects of chronic bioelectric nerve stimulation in health and diabetes

Background/AimsBioelectric nerve stimulation (eStim) is a novel clinical paradigm that can promote nerve regeneration after trauma, including within the context of diabetes. However, its ability to prevent the onset of diabetic peripheral neuropathy (DPN) has not yet been evaluated. Beyond the nerve itself, DPN has emerged as a potential contributor to sarcopenia and bone disease; thus, we hypothesized that eStim could serve as a strategy to simultaneously promote neural and musculoskeletal health in diabetes. MethodsTo address this question, an eStim paradigm pre-optimized to promote nerve regeneration was applied to the sciatic nerve, which directly innervates the tibia and lower limb, for 8-weeks in control and streptozotocin-induced type 1 diabetic (T1D) rats. Metabolic, gait, nerve and bone assessments were used to evaluate the progression of diabetes and the effect of sciatic nerve eStim on neuropathy and musculoskeletal disease, while also considering the effects of cuff placement and chronic eStim in otherwise healthy animals. ResultsRats with T1D exhibited increased mechanical allodynia in the hindpaw, reduced muscle mass, decreased cortical and cancellous bone volume fraction (BVF), reduced cortical bone tissue mineral density (TMD), and decreased bone marrow adiposity. T1D also had an independent effect on gait. Placement of the cuff electrode alone was sufficient to alter gait patterns and to promote unilateral reductions in tibia length, cortical BVF, and bone marrow adiposity. Alterations in gait patterns and left-right balance to tibia length were restored with eStim, but it did not prevent T1D-induced changes in muscle, bone, marrow adiposity or mechanical sensitivity. Beyond this, chronic eStim resulted in an independent, bilateral reduction in cortical TMD. ConclusionOverall, these results provide new insight into the pathogenesis of diabetic neuroskeletal disease and its regulation by eStim. Though eStim did not prevent neural or musculoskeletal complications in T1D, our results demonstrate that clinical applications of peripheral neuromodulation ought to consider the impact of device placement and eStim on long-term skeletal health in both healthy individuals and those with metabolic disease. This includes monitoring for compounded bone loss to prevent unintended consequences including decreased bone mineral density and increased fracture risk.

bioengineering↗