Basic Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 7, 2021; 27(33): 5566-5574
Published online Sep 7, 2021. doi: 10.3748/wjg.v27.i33.5566
Adiponectin and the regulation of gastric content volume in the newborn rat
Huanhuan Wang, Paul Esemu-Ezewu, Jingyi Pan, Julijana Ivanovska, Estelle B Gauda, Jaques Belik
Huanhuan Wang, Paul Esemu-Ezewu, Jingyi Pan, Julijana Ivanovska, Estelle B Gauda, Department of Paediatrics, The Hospital for Sick Children, Toronto M5G 1X8, Ontario, Canada
Jaques Belik, Department of Paediatrics and Physiology, The Hospital for Sick Children, Toronto M5G 1X8, Ontario, Canada
Author contributions: Wang H, Esemu-Ezewu P, Pan J and Ivanovska J performed the experiments, acquired and analyzed the data and contributed to drafting the manuscript; Gauda EB and Belik J designed, coordinated the study and finalized the manuscript.
Supported by Canadian Institutes of Health Research, No. CIA310955.
Institutional animal care and use committee statement: All procedures were conducted in accordance with the Canadian Animals for Research Act and Canadian Council on Animal Care regulations, and the Hospital for Sick Children Research Institute Animal Care Committee approved the study, No. 1000046424.
Conflict-of-interest statement: The authors have no conflict of interest to declare.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Jaques Belik, FRCP (C), MD, Professor, Department of Paediatrics and Physiology, The Hospital for Sick Children, 555 University Ave, Toronto M5G 1X8, Ontario, Canada.
Received: March 9, 2021
Peer-review started: March 9, 2021
First decision: May 1, 2021
Revised: May 12, 2021
Accepted: August 12, 2021
Article in press: August 12, 2021
Published online: September 7, 2021

Oral intake is dependent on the gastric ability to accommodate the food bolus. Comparatively, neonates have a smaller gastric capacity than adults and this may limit the volume of their milk intake. Yet, we previously reported that the newborn rat gastric milk volume is greatest after birth and, when normalized to body weight, decreases with postnatal age. Such age-dependent changes are not the result of intake differences, but greater gastric accommodation and reduced emptying rate.


Hypothesizing that breastmilk-derived adiponectin is the factor regulating gastric accommodation in neonates, we comparatively evaluated its effects on the rat fundic muscle tone at different postnatal ages.


In freshly dispersed smooth muscle cells (SMC), we measured the adiponectin effect on the carbachol-induced length changes.


Adiponectin significantly reduced the carbachol-stimulated SMC shortening independently of age. In the presence of the inhibitor iberiotoxin, the adiponectin effect on SMC shortening was suppressed, suggesting that it is mediated via large-conductance Ca2+ sensitive K+ channel activation. Lastly, we comparatively measured the newborn rat gastric milk curd adiponectin content in one- and two-week-old rats and found a 50% lower value in the latter.


Adiponectin, a major component of breastmilk, downregulates fundic smooth muscle contraction potential, thus facilitating gastric volume accommodation. This rodent’s adaptive response maximizes breastmilk intake volume after birth.

Keywords: Gastric emptying, Fundus, Smooth muscle, Breastmilk, Potassium channel, Development

Core Tip: Gastric accommodation regulates the stomach content volume. Lactating rats continuously breastfeed to keep a full gastric milk volume and their gastric emptying time is directly related to the gastric content volume. Little is known about the gastric fundic accommodation regulatory factors early in life. In this study, breastmilk-derived adiponectin is shown to promote gastric fundic relaxation, thus playing an important regulatory role during the lactating period.