This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Phospholipase C acts as second messenger for which of the following hormones? 
Select and explain. 
A. FSH, B. LH, C. TSH, D. GnRH
D: GnRH
Answer: D: GnRH 
Explanation: GnRH receptors are a pa of G protein coupled receptor superfamily and it functions primarily through the phospholipase C induced diacylglycerol and inositol triphosphate second messenger system. Second messengers used by hormones: CRH, ACTH, LH, FSH, TSH, PTH, calcitonin, glucagon, ADH (V2 receptor), hCG: increase cAMP. Prolactin: decrease cAMP. GHRH, GnRH, TRH, ADH (V1 receptor), oxytocin: DAG, IP3. Coisol, aldosterone, testosterone, estrogen, progesterone, calcitriol, thyroid hormones: Steroid mechanism. NO: cGMP. Insulin and IGF-1: Tyrosine kinase. Ref: Physiology By Robin R. Preston, page 439