beta-Adrenergic stimulated lipolysis in pony adipocytes is exclusively via a beta2-subtype and is not affected by lactation.
Abstract: Catecholamines are important lipolytic agents in horses and ponies but the nature of the adrenergic receptor subtype distribution in their adipocytes is uncertain. A first objective was to identify the beta-adrenergic receptor subtype(s) present in adipocytes from horses and ponies. A second objective was to evaluate if the lipolytic responsiveness of isolated adipocytes to beta-adrenergic agonists is altered during lactation, a condition known to affect markedly maternal fat metabolism. Isoproterenol and salbutamol elicited strong lipolytic responses in adipocytes isolated from horse and pony subcutaneous adipose tissue. There were weak lipolytic responses to norepinephrine, dobutamine and BRL37344. The weak lipolytic response to NE compared to isoproterenol or salbutamol suggests an antilipolytic action from alpha2-adrenergic receptors. The relative order of potency for the beta-adrenergic agonists was isoproterenol>/=salbutamol>>dobutamine=BRL37344. There was expression of beta2-adrenergic receptor mRNA in pony and horse adipose tissues, as estimated by relative RT-PCR, but no expression of mRNAs for beta1- or beta3-adrenergic receptors. Early lactation did not alter the lipolytic responses to beta-adrenergic agonists, nor the expression of beta2-adrenergic receptor mRNA. Thus, these results indicate a dominant if not exclusive presence of beta2-adrenergic receptors in pony and horse adipocytes that is not affected by lactation.
Publication Date: 2003-09-27 PubMed ID: 14511750DOI: 10.1016/s1095-6433(03)00157-0Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research aims to understand the type of beta adrenergic receptor present in horse and pony adipocytes (fat cells) and its possible changes during lactation. The findings reveal that a specific type – beta2-adrenergic receptor, is dominant and does not change during lactation.
Beta-adrenergic Receptor Study in Horse and Pony
- The study began with an objective to identify the beta-adrenergic receptor subtype in the fat cells of horses and ponies. Adrenergic receptors are part of the process that breaks down fat in the body and understanding their distribution in the adipocytes helps study the fat metabolism process.
- This was carried out using substances known as beta-adrenergic agonists, specifically isoproterenol and salbutamol, which are known to stimulate these receptors. The results indicated strong lipolytic responses, meaning they were efficient in breaking down fat.
- Comparatively, weaker responses were obtained from norepinephrine, dobutamine, and BRL37344, indicative of their poor fat-breaking abilities. The researchers suggest this might be due to inhibition from another type of receptors – alpha2-adrenergic receptors.
- Therefore, the relative order of efficiency was isoproterenol approximately equal to salbutamol and then significantly greater than dobutamine equals BRL37344.
Expression and Lipolytic Responses Study
- The next step was to evaluate the lipolytic response during lactation, regarded as a significant factor affecting maternal fat metabolism. They hypothesized that lactation could alter the responsiveness of the isolated fat cells to these beta-adrenergic agonists.
- But the research concluded that early lactation did not significantly alter the beta-adrenergic agonists’ lipolytic responses or the expression of the beta2-adrenergic receptor mRNA (messenger RNA).
- Furthermore, they revealed beta2-adrenergic receptor mRNA expression in the adipose tissues of horses and ponies, but found no expression for either the beta1- or beta3-adrenergic receptors.
Conclusion
- Overall, the study concludes that the fat cells of horses and ponies seem to have a dominant, if not exclusive, presence of beta2-adrenergic receptors.
- Moreover, their function and presence don’t appear to be influenced by lactation, which is noteworthy information about the fat metabolism process during this period.
Cite This Article
APA
Carrington EF, Desautels M, Naylor JM.
(2003).
beta-Adrenergic stimulated lipolysis in pony adipocytes is exclusively via a beta2-subtype and is not affected by lactation.
Comp Biochem Physiol A Mol Integr Physiol, 136(2), 311-320.
https://doi.org/10.1016/s1095-6433(03)00157-0 Publication
Researcher Affiliations
- University of Saskatchewan, Western College of Veterinary Medicine, Department of Large Animal Clinical Sciences, 52 Campus Drive, 107 Wiggins Road, S7N5B4, Saskatoon, SK, Canada. desautel@duje.usask.ca
MeSH Terms
- Adipocytes / metabolism
- Adrenergic alpha-Agonists / pharmacology
- Adrenergic beta-Agonists / pharmacology
- Animals
- Dobutamine / pharmacology
- Ethanolamines / pharmacology
- Female
- Horses / physiology
- Lactation / physiology
- Lipolysis / physiology
- Norepinephrine / pharmacology
- Receptors, Adrenergic, beta-2 / physiology
Citations
This article has been cited 1 times.- Murata D, Yamasaki A, Matsuzaki S, Sunaga T, Fujiki M, Tokunaga S, Misumi K. Characteristics and multipotency of equine dedifferentiated fat cells. J Equine Sci 2016;27(2):57-65.
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