From Intestinal Permeability to Dysmotility: The Biobreeding Rat as a Model for Functional Gastrointestinal Disorders

Abstract

BackgroundImpaired intestinal barrier function, low-grade inflammation and altered neuronal control are reported in functional gastrointestinal disorders. However, the sequence of and causal relation between these events is unclear, necessitating a spontaneous animal model. The aim of this study was to describe the natural history of intestinal permeability, mucosal and neuromuscular inflammation and nitrergic motor neuron function during the lifetime of the BioBreeding (BB) rat.MethodsNormoglycemic BB-diabetes prone (DP) and control rats were sacrificed at different ages and jejunum was harvested to characterize intestinal permeability, inflammation and neuromuscular function.ResultsBoth structural and functional evidence of increased intestinal permeability was found in young BB-DP rats from the age of 50 days. In older animals, starting in the mucosa from 70 days and in half of the animals also in the muscularis propria from 110 days, an inflammatory reaction, characterized by an influx of polymorphonuclear cells and higher myeloperoxidase activity, was observed. Finally, in animals older than 110 days, coinciding with a myenteric ganglionitis, a loss of nitrergic neurons and motor function was demonstrated.ConclusionIn the BB-rat, mucosal inflammatory cell infiltration is preceded by intestinal barrier dysfunction and followed by myenteric ganglionitis and loss of nitrergic function. This sequence supports a primary role for impaired barrier function and provides an insightful model for the pathogenesis of functional gastrointestinal disorders.

Colonic hypersensitivity and low‐grade inflammation in a spontaneous animal model for functional gastrointestinal disorders

“…At the gastrointestinal level, diabetic animals show evidence of increased intestinal permeability, prior to onset of diabetes, combined with transmural intestinal inflammation and loss of nitrergic motor neuron function which results in disordered motility. Previous work from our group demonstrated an early jejunal hyperpermeability in normoglycemic BB‐rats (BBDP‐N) preceding a polymorphonuclear (PMN) granulocyte infiltration, including mast cells and eosinophils, starting in the lamina propria and progressively expanding to the jejunal neuromuscular layers in a subset of rats . Together, these data suggest a disease‐initiating role for intestinal permeability in the gastrointestinal impairments observed in the BBDP‐N that finally lead to motor dysfunction.…”

“…Glycemia was measured on tail blood on a weekly basis using a OneTouch ® Verio ® glucometer (LifeScan) starting from 70 days of age. Diabetes onset was characterized by glycemia values above or equal to 250 mg/dL on two consecutive occasions . As the purpose of the current study focused on gastrointestinal features unrelated with hyperglycemia, only BBDR and normoglycemic BBDP (BBDP‐N) rats were included.…”

“…BBDR and BBDP‐N rats of 50, 90, 160, and 220 days old were euthanized by cervical dislocation and exsanguination (n ≥ 7 per group). These time points were selected based on previous work reporting altered intestinal permeability in BBDP‐N rats starting from 50 days, prior to the onset of diabetes, followed by a progressive transmural immune cell infiltration at later time points (90, 160, and 220 days). After euthanasia, blood was collected in a 10‐mL BD Vacutainer ® tube containing 18 mg EDTA (BD), and colon was harvested and stored in ice‐cold Krebs‐Ringer buffer (2.5 mmol/L CaCl 2 , 5.9 mmol/L KCl, 1.2 mmol/L MgCl 2 , 120.9 mmol/L NaCl, 14.4 mmol/L NaHCO 3 , 1.2 mmol/L NaH 2 PO 4 , and 11.5 mmol/L glucose; all purchased from Merck, Overijse, Belgium), continuously gassed with carbogen (95% O 2 , 5% CO 2 ) until further processing.…”

“…Sections of 5 µm were cut using a microtome and stained with hematoxylin and eosin (H&E). Similar to our previous study in the small intestine, polymorphonuclear (PMN) granulocytes were counted in the lamina propria in five non‐overlapping high‐power fields and in 50 ganglia of the myenteric plexus in a blinded fashion . A ganglion was defined as a collection of at least two adjacent neuronal cell bodies.…”

MiR-144 Increases Intestinal Permeability in IBS-D Rats by Targeting OCLN and ZO1

“…Disruption of the intestinal tight junctions may be a critical underlying pathophysiologic factor in patients with any of several inflammatory conditions, including coeliac disease [3], inflammatory bowel disease [4], food allergies [5] and type 1 diabetes [6]. The current understanding of the in vivo molecular mechanisms of increased intestinal permeability in patients with gastrointestinal disorders remains limited [7]. Thus, the identification of factors that regulate the intestinal permeability holds potential for identifying novel targets to prevent IBS-D.…”