1. ACTH & MSH
By: Zachary Lopez

2. Production of POMC
Corticotropin releasing hormone is sent from the hypothalamus 
Causes anterior pituitary to synthesize tropic hormone in corticotroph cells
Proopiomelanocortin(POMC) is a chain of 241 amino acids, which is the precursor to many biologically active substances

3. Cleavage of POMC
Depending on the tissue types and available convertases, POMC is enzymatically cleaved into multiple peptides.

4. Structure of ACTH
Consists of the peptide chain between 138 to 176 of the POMC
Human ACTH has a molecular weight of 4,540 Da.

5. Function of ACTH
Stimulates secretion of glucocorticoids from adrenal cortex cells
Facilitates cholesterol delivery to the mitochondria
Stimulates lipoprotein uptake into cortical cells increasing the bioavailability of cholesterol in the adrenal cortex

6. Regulation
Glucocorticoids inhibit further secretion of CRH from the hypothalamus
Glucocorticoids may also inhibit rates of POMC transcription
Half-life in human blood is approximately ten minutes

7. Problems with ACTH
ACTH levels are diurnal with normal ranges between 5-50 pg/ml
Levels exceeding normal ranges may result in Cushing's syndrome, characterized by puffy appearance and skin redness
Low levels of ACTH may lead to Addison's disease, which is a case of severe electrolyte imbalance and dehydration.

9. Structure of MSH
Different forms of MSH have different amino acid sequences
 α-MSH: Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val
β-MSH: Ala-Glu-Lys-Lys-Asp-Glu-Gly-Pro-Tyr-Arg-Met-Glu-His-Phe- Arg-Trp-Gly-Ser-Pro-Pro-Lys-Asp
γ-MSH: Tyr-Val-Met-Gly-His-Phe-Arg-Trp-Asp-Arg-Phe-Gly

10. Functions of MSH
Acts as an anti-inflammatory and a regulatory peptide hormone
Involved with production and release of melanin from melanocytes
Also has hypothalamic control of sleep through melatonin, endorphins, and sexual arousal
Critical in the regulation of hunger 

11. MSH and appetite
MSH binds to melanocortin receptors to decrease hunger
Expression occurs in the arcuate nucleus of the hypothalamus

12. MSH and appetite
Ghrelin stimulates the hypothalamus to release glutamate
Glutamate synapses with AgRP and NPY neurons which induce the feeding response
AgRP and NPY neurons inhibit POMC neurons

13. Regulation Produced in the intermediate lobe of the pituitary
Melanocortin 1 receptors(MC1R) is primarily involved in melanin production in melanocytes
Melanocortin receptors 3 & 4 are involved with hunger, sleep, and sexual arousal
The type of MSH affects the expression of the hormone

14. Melanin
Melanin- an effective absorber of light, protects against UVB radiation which reduces cancer risk
Eumelanin- most common, two types(brown and black)
Pheomelanin- responsible for red hair, possible expression through agouti signaling peptide
Neuromelanin- found exclusively in the brain

15. MSH Deficiency
Damage to MC4R may result in increased food intake and obesity
Hypopituitarism: when the pituitary doesn’t produce enough of one of its hormones. Results in inflammation, pain, reduction in ADH, and frequent thirst/urination
Albinism: abnormality in the melanin formation pathway

16. The End