Growth Hormone/ Structure, Function, and dysfunction

what causes DM in feline acromegaly?

a tumor secreting growth hormone

what is growth hormone?

a peptide hormone produced by the anterior pituitary gland that is controlled mostly by the hypothalamic GHRH

How is GH released?

in a pulsatile fashion with superimposed peaks caused by starvation, ghrelin, stress, and progesterone in dogs

When are GH levels the highest?

during adolescence

what are insulin growth factors?

proteins that mediate the effects of growth hormone, promoting growth and development in various tissues.

what does growth hormone have direct metabolic effects on?

GH-receptors on target cells

what does growth hormone have indirect effects?

the stimulation of IDFs in the liver with the release of IGF-1 into circulation and in all tissues as local paracrines and autocrines via IDF- receptors

What affect will elevated IGF-1 have on GH?

negative feedback to produce less

What is the affect of GH in a low energy situation?

It promotes energy conservation by reducing glucose uptake and increasing fat utilization. Also promotes insulin resistance.

what is the affect of GH in a high energy situation?

at high insulin levels GH receptors are upregulated, IDF effects dominate and stimulate protein anabolism. Growth, repair, maintenance

What are the expect effects of a puppy with panhypopituitarism?

Deficiencies in thyroid hormones, growth hormone, adrenal hormones, and gonad hormones

what is acromegaly?

functional pituitary tumors secreting excess growth hormone (cats) or extended periods of high progesterone levels stimulating GH release from the mammary gland (dogs : during diestrus or due to contraceptive use)

what are the effects of acromegaly on protein and carb metabolism?

hypertrophy of muscle incl cardo and organs, increased bone and cartilage thickness especially face digits and joints, increased gluconeogenesis and inulin resistance

how can acromegaly induce secondary DM?

Excess growth hormone leads to increased gluconeogenesis and insulin resistance, which can result in secondary diabetes mellitus.

what are some acromegaly signs in animals?

joint problems, increased body weight, facial broadening, paw enlargement, prognathia with increased interdental spaces, teeth shifting, laryngeal hypertrophy, respiratory issues, tongue enlargement, organomegaly

what are some treatment options for animals with acromegaly?

stereotactic radiation therapy, surgery, somatastatin analogs, insulin

what are some diagnostic tests used for acromegaly?

hormone assays of GH and IGF-1 levels, MRI of the pituitary gland, glucose tolerance test.