Effect of corticotropin-like intermediate lobe peptide on pancreatic exocrine function in isolated rat pancreatic lobules.

Summary Background Pituitary pars intermedia dysfunction (PPID) is a commonly described endocrine disorder in higher latitudes of the Northern hemisphere but the description of the disease at lower latitudes and in the Southern hemisphere is limited. Objectives Document the clinical features of PPID at different Australian latitudes and climates, and investigate factors associated with survival, laminitis and insulin dysregulation (ID). Study design Retrospective study of 274 equids from eight institutions across Australia. Methods A diagnosis of PPID was based on endogenous ACTH, overnight dexamethasone suppression test, thyrotropin‐releasing hormone stimulation test or necropsy. Clinical and clinicopathologic characteristics of PPID and therapeutic responses were investigated. Laminitis was diagnosed by radiographic or histologic changes and ID was diagnosed based on endogenous insulin, an oral glucose test or a 2‐step insulin‐response test. Results Being a pony, having a higher body condition score and pergolide administration were associated with survival. The clinical presentation of PPID changed with latitude and climate, with anhidrosis and polyuria/polydipsia more commonly recognised at lower latitudes. Laminitis was diagnosed in 89.9% of cases and ID was present in 76.5% of cases in which they were investigated. Main limitations Despite the sample size, the lack of uniform testing at all locations (primary or referral cases) and the incompleteness of data sets limited the power of the statistical analyses. Conclusions PPID can present with variable signs at different latitudes and climates, and ID should be investigated in equids diagnosed with PPID. Adequate body condition and administration of pergolide are fundamental in PPID management.

Section: Discussionmentioning

confidence: 99%

Factors associated with survival, laminitis and insulin dysregulation in horses diagnosed with equine pituitary pars intermedia dysfunction

Horn

Bamford

Afonso

et al. 2018

“…Alternatively, PPID may induce or exacerbate ID and hyperinsulinaemia, particularly in animals that already have predisposing genetic or environmental risk factors. Pathologically high pituitary hormone concentrations can act as insulin secretagogues in pancreatic β‐cells and hepatic insulin clearance might be reduced as a result of mild hepatic dysfunction associated with obesity, PPID and/or ageing . Heterogeneity in the severity of pituitary lesions, as well as individual variability in the specific proopiomelanocortin‐derived peptide profile secreted by the diseased pars intermedia , might explain why PPID only induces ID in a subset of affected animals.…”

Section: Discussionmentioning

confidence: 99%

Association between hyperinsulinaemia and laminitis severity at the time of pituitary pars intermedia dysfunction diagnosis

Tadros

Fowlie

Refsal

et al. 2018

“…Corticotropin‐like intermediate peptide is a derivative of pro‐opiomelanocortin and adrenocorticotrophic hormone (amino acids 18–39), and concentrations increase in horses with PPID . This hormone acts as an insulin secretagogue when added to the media of pancreatic explants , and might therefore contribute to the development of hyperinsulinaemia in equine PPID. Alpha melanocyte‐stimulating hormone (αMSH) concentrations are also increased with PPID and this hormone, along with leptin, plays an important role in energy metabolism.…”

Section: Insulin Resistancementioning

confidence: 99%

Insulin dysregulation

Frank

Tadros

2013

166

174

SummaryAbnormalities of insulin metabolism include hyperinsulinaemia and insulin resistance, and these problems are collectively referred to as insulin dysregulation in this review. Insulin dysregulation is a key component of equine metabolic syndrome: a collection of endocrine and metabolic abnormalities associated with the development of laminitis in horses, ponies and donkeys. Insulin dysregulation can also accompany prematurity and systemic illness in foals. Causes of insulin resistance are discussed, including pathological conditions of obesity, systemic inflammation and pituitary pars intermedia dysfunction, as well as the physiological responses to stress and pregnancy. Most of the discussion of insulin dysregulation to date has focused on insulin resistance, but there is increasing interest in hyperinsulinaemia itself and insulin responses to feeding. An oral sugar test or in-feed oral glucose tolerance test can be performed to assess insulin responses to dietary carbohydrates, and these tests are now recommended for use in clinical practice. Incretin hormones are likely to play an important role in postprandial hyperinsulinaemia and are the subject of current research. Insulin resistance exacerbates hyperinsulinaemia, and insulin sensitivity can be measured by performing a combined glucose-insulin test or i.v. insulin tolerance test. In both of these tests, exogenous insulin is administered and the rate of glucose uptake into tissues measured. Diagnosis and management of hyperinsulinaemia is recommended to reduce the risk of laminitis. The term insulin dysregulation is introduced here to refer collectively to excessive insulin responses to sugars, fasting hyperinsulinaemia and insulin resistance, which are all components of equine metabolic syndrome.