Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Karina Matos Fernandez - University of Puerto Rico, Ponce
Co-Author(s): Mrigendra Rajput, Michigan State University, MI; Yihang Li, Michigan State University, MI
Gastrointestinal nerves are important for proper nutrient absorption 1 in the gut. These nerves comprise the enteric nervous system, which regulates the absorption of nutrients by controlling the nutrient transporter’s activity. Moreover, this activity can be altered by stress, thus exerting a detrimental effect on the normal functioning of the intestines that could eventually contribute to the development of gastrointestinal diseases. However, it is poorly understood how undergoing through early-life stress events affects the development, function and neuronal regulation of nutrient’s transporters.
The objectives of the present study were: to assess the effects of early-life stress on nutrient absorption in the small intestine by examining the development, function, and neuronal regulation of nutrient transporters’, specifically, cholinergic and adrenergic neurons. To accomplish these goals, 16 female piglets were randomly assigned between early weaning (EW; weaned at 15 days of age; ELS model group) and late weaning stress groups (LW; weaned at 29 days of age; control group). At 70 days of age, small intestine samples were collected to evaluate the electrogenic nutrient transport activity using the Ussing Chambers technique. Neuronal regulation of nutrient transport was evaluated by pretreatment of intestinal tissues with neural
blockers: tetrodotoxin (TTX; sodium channel blocker), atropine (ATR; muscarinic-acetylcholine receptor antagonist), hexamethonium (HEXA; nicotinic-acetylcholine receptor antagonist), and propranolol (PRO; beta-adrenoreceptor blocker) prior to addition of luminal glucose and selected amino acids. The short-circuit current (Isc ) response of serial addition of nutrient treatments on the mucosal side was recorded and delta Isc of each nutrient response was calculated. We hypothesized that ELS will induce chronic impairment to glucose and amino acid transporters mediated via the enteric nervous system. By analyzing the individual nutrient-induced increase in tissue short-circuit current (? Isc), we found a significant suppression (P < 0.05) of glucose, alanine, and glutamate transport, but a significant enhancement (P < 0.05) of
lysine transport in EW pigs compared with LW control pigs. Interestingly, ATR-treated tissue reduced lysine transport (by 50 %) in EW pigs, but not in LW pigs.
Together, these data suggest that early psychological stress in a porcine model of ELS has long-lasting effects on nutrient transport in the porcine small intestine, which may be regulated by alterations in cholinergic nervous system activity. These results provide new insight into the pathophysiology of intestinal diseases associated with early life stress, such as inflammatory bowel disease, which could lead to novel nutritional strategies for humans and animals.
Guilles, M. 2015. Nutrient sensing by the gastrointestinal nervous system and control of energy homeostasis. Biologie Aujourd'hui. 209(4): 325-30
; Magalhes, D., Cabral, J.M., Soares-da-Silva, P. & Magro, F. 2016. Role of Epithelial Ion Transports in Inflammatory Bowel Disease. American Journal of Physiology. 310(7): G460-G476
Funder Acknowledgement(s): The authors would like to thank Kevin Turner and the MSU Swine Research and Teaching Unit. This work was supported by grants from the National Institutes of Health R01 HD072968 (to A.J.M.), Unites States Department of Agriculture (USDA) grant #2016-09526, and ENDURE R25NS090989.
Faculty Advisor: Adam Moeser, firstname.lastname@example.org
Role: Roles in the project: sedated pigs by intramuscular injection, performed surgery through ventral midline abdominal incisions, dissected small intestine samples from jejunum and ileum, euthanized pigs by intracardiac injection of pentobarbital sodium, added nutrients and neuronal blockers to the Ussing Chamber containing the samples, set-up and troubleshooting of multichannel Ussing Chamber, scrapings of mucosal tissue, assessed gene expression of CHRM3, ?7-nAChR, ADRB1, ADRB2, B-actin and RPL4 from mucosal tissue by RT-PCR, prepared Ringer and neuronal blockers solutions, prepared the agar-bridge electrodes, for histological analysis: villi were measured for villus height and crypt depth using Image J, for the electrophysiological measurements: data was plotted and analyzed using PRISM.