This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Female Reproductive System, Subject name: Physiology
Before the onset of pubey, the GnRH neurons are under the inhibitory control of: 
Select and explain. 
A. Glycine, B. Glutamate, C. Gamma amino butyric acid (GABA), D. Beta-endorphin
C: Gamma amino butyric acid (GABA)
Answer: C: Gamma amino butyric acid (GABA) 
Explanation: The transition to a reproductive state (during pubey) requires maturation of the entire hypothalamic-pituitary-gonadal axis. Before this maturation occurs, plasma LH and FSH levels are diminished despite low concentrations of gonadal steroids and inhibin. GnRH neurons are said to be under inhibitory influence of GABAergic neurons. Additional inhibition comes from NPY, endorphins, and nocturnal melatonin secretion. Hence, option C is more appropriate.