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Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na+/glucose cotransporter SGLT1.

Abstract

INTRODUCTION

the intestinal Na(+)/glucose cotransporter (SGLT1) displays rapid anticipatory diurnal rhythms in mRNA and protein expression. The vagus nerve has been implicated in the entrainment of some transporters. We aimed to clarify the influence of the vagus nerve on the diurnal entrainment pathway for SGLT1 and examine the role of vagal afferent fibers.

METHODS

male Sprague-Dawley rats were randomized to three groups, total subdiaphragmatic vagotomy, selective deafferentation of the vagus with capsaicin, or sham laparotomy. Postoperatively, animals were maintained in a 12-h light-dark cycle with food access limited to night. On the ninth postoperative day, animals were euthanized to harvest jejunal mucosa at 6-h intervals starting at 10 AM. Whole cell SGLT1 protein was measured by semiquantitative densitometry of immunoblots. Sglt1 and regulatory subunit RS1 mRNA was assessed by quantitative PCR. Fluorogold tracer technique was used to confirm adequacy of the vagotomy.

RESULTS

the diurnal rhythm in intestinal SGLT1, with a 5.3-fold increase in Sglt1 mRNA at 4 PM, was preserved in both vagotomy and capsaicin groups. However, the rhythmicity in SGLT1 protein expression (2.3-fold peak at 10 PM; P = 0.041) was abolished following either total vagotomy or deafferentation. Lack of change in RS1 mRNA suggests this is independent of the RS1 regulatory pathway.

CONCLUSION

SGLT1 transcription is independent of the vagus. However, dissociation of the protein rhythm from the underlying mRNA signal by vagotomy suggests the vagus may be involved in posttranscriptional regulation of SGLT1 in an RS1 independent pathway. Disruption following afferent ablation by capsaicin suggests this limb is specifically necessary.

Authors+Show Affiliations

Dept. of Surgery, Brigham & Women's Hospital, 75 Francis St., Boston, MA 02115, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18308853

Citation

Stearns, Adam T., et al. "Capsaicin-sensitive Vagal Afferents Modulate Posttranscriptional Regulation of the Rat Na+/glucose Cotransporter SGLT1." American Journal of Physiology. Gastrointestinal and Liver Physiology, vol. 294, no. 4, 2008, pp. G1078-83.
Stearns AT, Balakrishnan A, Rounds J, et al. Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na+/glucose cotransporter SGLT1. Am J Physiol Gastrointest Liver Physiol. 2008;294(4):G1078-83.
Stearns, A. T., Balakrishnan, A., Rounds, J., Rhoads, D. B., Ashley, S. W., & Tavakkolizadeh, A. (2008). Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na+/glucose cotransporter SGLT1. American Journal of Physiology. Gastrointestinal and Liver Physiology, 294(4), pp. G1078-83. doi:10.1152/ajpgi.00591.2007.
Stearns AT, et al. Capsaicin-sensitive Vagal Afferents Modulate Posttranscriptional Regulation of the Rat Na+/glucose Cotransporter SGLT1. Am J Physiol Gastrointest Liver Physiol. 2008;294(4):G1078-83. PubMed PMID: 18308853.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Capsaicin-sensitive vagal afferents modulate posttranscriptional regulation of the rat Na+/glucose cotransporter SGLT1. AU - Stearns,Adam T, AU - Balakrishnan,Anita, AU - Rounds,Jan, AU - Rhoads,David B, AU - Ashley,Stanley W, AU - Tavakkolizadeh,Ali, Y1 - 2008/02/28/ PY - 2008/3/1/pubmed PY - 2008/5/23/medline PY - 2008/3/1/entrez SP - G1078 EP - 83 JF - American journal of physiology. Gastrointestinal and liver physiology JO - Am. J. Physiol. Gastrointest. Liver Physiol. VL - 294 IS - 4 N2 - INTRODUCTION: the intestinal Na(+)/glucose cotransporter (SGLT1) displays rapid anticipatory diurnal rhythms in mRNA and protein expression. The vagus nerve has been implicated in the entrainment of some transporters. We aimed to clarify the influence of the vagus nerve on the diurnal entrainment pathway for SGLT1 and examine the role of vagal afferent fibers. METHODS: male Sprague-Dawley rats were randomized to three groups, total subdiaphragmatic vagotomy, selective deafferentation of the vagus with capsaicin, or sham laparotomy. Postoperatively, animals were maintained in a 12-h light-dark cycle with food access limited to night. On the ninth postoperative day, animals were euthanized to harvest jejunal mucosa at 6-h intervals starting at 10 AM. Whole cell SGLT1 protein was measured by semiquantitative densitometry of immunoblots. Sglt1 and regulatory subunit RS1 mRNA was assessed by quantitative PCR. Fluorogold tracer technique was used to confirm adequacy of the vagotomy. RESULTS: the diurnal rhythm in intestinal SGLT1, with a 5.3-fold increase in Sglt1 mRNA at 4 PM, was preserved in both vagotomy and capsaicin groups. However, the rhythmicity in SGLT1 protein expression (2.3-fold peak at 10 PM; P = 0.041) was abolished following either total vagotomy or deafferentation. Lack of change in RS1 mRNA suggests this is independent of the RS1 regulatory pathway. CONCLUSION: SGLT1 transcription is independent of the vagus. However, dissociation of the protein rhythm from the underlying mRNA signal by vagotomy suggests the vagus may be involved in posttranscriptional regulation of SGLT1 in an RS1 independent pathway. Disruption following afferent ablation by capsaicin suggests this limb is specifically necessary. SN - 0193-1857 UR - https://www.unboundmedicine.com/medline/citation/18308853/Capsaicin_sensitive_vagal_afferents_modulate_posttranscriptional_regulation_of_the_rat_Na+/glucose_cotransporter_SGLT1_ L2 - http://www.physiology.org/doi/full/10.1152/ajpgi.00591.2007?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -