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 H1receptor 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 negative chronotropic effect. Inverse agonist of H3 receptor (tiprolisant) is approved for Narcolepsy.