The H3 receptor agonist exhibits all   of the following actions EXCEPT
Inhibition of H1receptor induced wakefulness
Increase in H1 mediated gastrin secretion
Inhibition of H1 mediated bronchoconstriction
Negative chronotropic effect on atria
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.