Development of Laminitis — Possible Role of Adipose Tissue

Laminitis is associated with obesity as well as sepsis and post-operative conditions in horses where levels of inflammation are elevated. The precise mechanisms that lead to laminitis are unknown; however, several studies document the involvement of
Share
Favorite
Close

No account yet? Register

ADVERTISEMENT

Laminitis is associated with obesity as well as sepsis and post-operative conditions in horses where levels of inflammation are elevated. The precise mechanisms that lead to laminitis are unknown; however, several studies document the involvement of inflammation in the pathogenesis of laminitis. In addition, recent studies utilizing an in vitro approach to studying laminitis using hoof wall explants have shown that removal of glucose from the culture medium leads to rapid separation of hoof lamella tissue when subject to stress forces. A similar mechanism might occur in natural cases of laminitis where there is insulin resistance–a suppressed ability of insulin to induce glucose uptake into the cell. 

While numerous mechanisms contribute to the development of insulin resistance, growing evidence points to both a correlative and causative relationship between inflammation and insulin resistance. In addition to sepsis and surgery, obesity is also considered an inflammatory state that some studies relate to a localized form of Cushing’s syndrome. Circulating concentrations of inflammatory molecules–including acute phase proteins and inflammatory cytokines–are elevated in obese humans, with even higher elevations in obese patients with insulin resistance and type II diabetes. Further evidence indicating an inflammatory role in insulin resistance is derived from studies demonstrating a reversal of insulin resistance by administration of anti-inflammatory salicylates, such as aspirin.

Several key molecules involved in the development of insulin resistance have come to the forefront in recent years and have led researchers to investigate adipose tissue as a major player in the regulation of insulin sensitivity. Adipose tissue, once considered only a reservoir for energy storage, has emerged as an endocrine organ and an active participant in whole body energy homeostasis. A number of factors directly contributing to insulin resistance, such as the inflammatory cytokine TNF-alpha, are synthesized and secreted by adipose tissue. Additionally, studies have shown that adipose tissue contribute a considerable percentage of the circulating inflammatory molecules IL-6 and TNF-alpha, with degree of contribution correlating to degree of obesity in humans. Thus, the significance of excess adipose tissue as a major contributor to the development of insulin resistance cannot be understated.

Preliminary studies in our laboratory have employed a model for inducing inflammation. This model investigates a) the relationship between inflammation and insulin resistance, and b) the possible role of adipose tissue as a contributor of inflammatory molecules in insulin resistance in the horse. Administration of lipopolysaccharide (LPS), part of the cell wall of the bacteria E. coli, is a commonly used model for inducing inflammation. LPS induces an acute but transient inflammatory response characterized by elevation in heart rate, temperature, respiration, and insulin levels over a period of several hours. It is also well documented that administration of LPS in the horse induces increased circulating levels of the inflammatory cytokine TNF-alpha in blood. The objectives of the study were to determine whether insulin resistance results from a direct inflammatory stimulus in the horse and measure inflammatory cytokine mRNA expression in adipose tissue in response to LPS

Create a free account with TheHorse.com to view this content.

TheHorse.com is home to thousands of free articles about horse health care. In order to access some of our exclusive free content, you must be signed into TheHorse.com.

Start your free account today!

Already have an account?
and continue reading.

Share

Written by:

Related Articles

Stay on top of the most recent Horse Health news with

FREE weekly newsletters from TheHorse.com

Sponsored Content

Weekly Poll

sponsored by:

How much time do you usually spend grooming your horse?
439 votes · 439 answers

Readers’ Most Popular

Sign In

Don’t have an account? Register for a FREE account here.

Need to update your account?

You need to be logged in to fill out this form

Create a free account with TheHorse.com!