Background and Aims Bowel function requires coordinated activity of diverse enteric neuron subtypes. Our aim was to define gene expression in these neuron subtypes to facilitate development of novel therapeutic approaches to treat devastating enteric neuropathies, and to learn more about enteric nervous system function. Methods To identify subtype–specific genes, we performed single-nucleus RNA-seq on adult mouse and human colon myenteric plexus, and single-cell RNA-seq on E17.5 mouse ENS cells from whole bowel. We used immunohistochemistry, select mutant mice, and calcium imaging to validate and extend results. Results RNA-seq on 635 adult mouse colon myenteric neurons and 707 E17.5 neurons from whole bowel defined seven adult neuron subtypes, eight E17.5 neuron subtypes and hundreds of differentially expressed genes. Manually dissected human colon myenteric plexus yielded RNA-seq data from 48 neurons, 3798 glia, 5568 smooth muscle, 377 interstitial cells of Cajal, and 2153 macrophages. Immunohistochemistry demonstrated differential expression for BNC2, PBX3, SATB1, RBFOX1, TBX2, and TBX3 in enteric neuron subtypes. Conditional Tbx3 loss reduced NOS1-expressing myenteric neurons. Differential Gfra1 and Gfra2 expression coupled with calcium imaging revealed that GDNF and neurturin acutely and differentially regulate activity of ∼50% of myenteric neurons with distinct effects on smooth muscle contractions. Conclusion Single cell analyses defined genes differentially expressed in myenteric neuron subtypes and new roles for TBX3, GDNF and NRTN. These data facilitate molecular diagnostic studies and novel therapeutics for bowel motility disorders.
Background Intravenous continuous rate infusion (IVCRI) of lispro at a starting dose of 0.09 U/kg/h and the use of 0.9% sodium chloride (NaCl) for fluid resuscitation in cats with diabetic ketoacidosis (DKA) have not been reported. Protocols for correction of electrolyte deficiencies in cats with DKA are lacking. Objectives To characterize the use of IVCRI lispro at an initial dose of 0.09 U/kg/h and the use of NaCl for resuscitation. Explore protocols for electrolyte supplementation in cats with DKA. Animals Twelve cats with DKA enrolled from the cat population of a university hospital. Methods Randomized, controlled, blinded study. Six cats were randomized into each group, the lispro insulin treatment group (LITG) and regular insulin treatment group (RITG). All cats received IVCRI fluid resuscitation with NaCl. Solutions with higher than previously published electrolyte concentrations were used to treat electrolyte deficiencies. Results The median time to blood glucose (BG) concentration <250 mg/dL was significantly shorter in the LITG (median 7 hours, 2‐10 hours) than the RITG (median 12.5 hours, 8‐20 hours; P = .02). Two cats had nonclinical hypoglycemia (BG = 40 mg/dL). The most rapid change in 157 measurements of corrected sodium concentrations was 0.7 mmol/L/h. Low concentrations of serum sodium, potassium, phosphate, and magnesium were over 3 times more common than above normal electrolyte concentrations, despite supplementation with fluids of high electrolyte concentrations. Conclusions and Clinical Importance Lispro at a starting dose of 0.09 U/kg/h and NaCl administered for fluid resuscitation are safe and effective for treatment of DKA in cats.
Retinoic acid (RA) signaling is essential for enteric nervous system (ENS) development since vitamin A deficiency or mutations in RA signaling profoundly reduce bowel colonization by ENS precursors. These RA effects could occur because of RA activity within the ENS lineage or via RA activity in other cell types. To define cell-autonomous roles for retinoid signaling within the ENS lineage at distinct developmental time points, we activated a potent floxed dominantnegative RA receptor α (RarαDN) in the ENS using diverse CRE recombinase-expressing mouse lines. This strategy enabled us to block RA signaling at pre-migratory, migratory, and postmigratory stages for ENS precursors. We found that cell-autonomous loss of retinoic acid receptor (RAR) signaling dramatically affects ENS development. CRE activation of RarαDN expression at pre-migratory or migratory stages caused severe intestinal aganglionosis, but at later stages, RarαDN induced a broad range of phenotypes including hypoganglionosis, submucosal plexus loss, and abnormal neural differentiation. RNA-sequencing highlighted distinct RA-regulated gene sets at different developmental stages. These studies show complicated context-dependent RAmediated regulation of ENS development.
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