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: Pharmacology
The H3 receptor agonist exhibits all of the following actions EXCEPT : 
Select and explain. 
A. Inhibition of H1 receptor induced wakefulness, B. Increase in H1 mediated gastrin secretion, C. Inhibition of H1 mediated bronchoconstriction, D. Negative chronotropic effect on atria
B: Increase in H1 mediated gastrin secretion
Answer: B: Increase in H1 mediated gastrin secretion 
Explanation: H3 receptors act as pre-synaptic receptors and decrease the release of histamine and other neurotransmitters. These an­tagonize H1 mediated wakefulness and bronchoconstriction. These also decrease gastrin release and produce the negative chronotropic effect. An inverse agonist of H3 receptor (tiprolisant) is approved for Narcolepsy.