Final answer:
PPID is caused by a dysfunction in the pituitary pars intermedia due to a loss of inhibitory dopamine signals, leading to the overproduction of hormones. This mirrors similar malfunctions in humans where pituitary hormone regulation is impacted, affecting various physiological activities.
Step-by-step explanation:
PID, commonly known as Equine Cushing’s Disease, is caused by an abnormal increase in hormonal secretion from the pituitary gland. Specifically, the pituitary pars intermedia, a part of the gland that normally does not highly contribute to hormone production, becomes hyperactive. This hyperactivity can be attributed to a degeneration of the dopamine neurons that typically inhibit the pars intermedia cells. Without this inhibitory effect, the pars intermedia cells overproduce hormones such as ACTH, leading to the overstimulation of adrenal glands and subsequent symptoms associated with PPID.
The pituitary gland, which is suspended from the hypothalamus, plays a critical role in regulating various hormonal functions throughout the body. Conditions such as pituitary dwarfism in children and PPID in horses occur when there is a dysregulation in hormone production. PPID is similar to some human conditions where the pituitary gland malfunctions, affecting bodily processes ranging from growth and metabolism to reproduction and water balance.