This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nerve Physiology, Subject name: Physiology
Opioid secreted from anterior pituitary? 
Select and explain. 
A. b endorphin, B. GH, C. ACTH, D. MSH
A: b endorphin
Answer: A: b endorphin 
Explanation: (A) b endorphin# Pro-opiomelanocortin, a large precursor molecule found in anterior and intermediate lobes of pituitary gland and brain, contains b-endorphin, a polypeptide of 31 AA residues, that has met enkephalin at its amino terminal.> There are separate enkephalin secreting and fi-endorphin secreting systems of neurons in brain.> b-endorphin is also secreted into the bloodstream by pituitary gland.