Animal models of Cushing’s disease.

The research article investigates Cushing’s disease in animals, specifically dogs and horses, with a focus on how pituitary ACTH excessive secretion contributes to its occurrence and the role pituitary tumors play in the disease’s development.

Overview of Cushing’s Disease

• Cushing’s disease, scientifically referred to as hyperadrenocorticism, is characterized by the overproduction of the hormone, adrenocorticotropic hormone (ACTH), produced in the pituitary gland.
• The excess production of ACTH causes an increase in cortisol levels, a hormone that aids in managing stress and maintaining functions such as metabolism and immune response.

Observation in Animals

• The researchers discovered that Cushing’s disease occurs naturally and quite often in animals, focusing their study mainly on dogs and horses.
• The manifestation of the disease in these animals presents an opportunity to understand the disease further due to their higher occurrence rate as opposed to other species.

Role of Pituitary Tumours in Cushing’s Disease

• Based on the research, in most instances, Cushing’s disease in dogs and humans is associated with a small tumor located in a part of the pituitary gland known as the pituitary pars distalis.
• However, the disease can sometimes originate from tumors or an increase in the number or size of cells (hyperplasia) in another part of the pituitary gland, the pituitary pars intermedia – an area frequently affected in horses.

Cellular Origin of Pars Intermedia Tumours

• In dogs, tumors in pars intermedia can emerge from either of the two cell types that contain proopiomelanocortin (POMC) present in the normal tissue. POMC is a precursor polypeptide with many biological functions, including the synthesis of ACTH.