<prompt> The H3 receptor agonist exhibits all of the following actions except:Inhibition of H1 receptor induced wakefulnessIncrease in H1 mediated gastrin secretionInhibition of H1 mediated bronchoconstrictionNegative chronotropic effect on atria  <response>: Ans. B Increase in H1 mediated gastrin secretionRef: KDT 6the p153H3 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. 