The H3 receptor agonist exhibits all of the following actions EXCEPT :
Inhibition of H1 receptor 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 the negative chronotropic effect. An inverse agonist of H3 receptor (tiprolisant) is approved for Narcolepsy.