In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.

[Q]: Histamine enhances the depolarizing afterpotential of immunohistochemically identified vasopressin neurons in the rat supraoptic nucleus via H1-receptor activation.
[A]: H1-receptor


[Q]: The antitussive activity of delta-opioid receptor stimulation in guinea pigs.
[A]: delta-opioid receptor


[Q]: Effects of the histamine H1 antagonist chlorcyclizine on rat fetal palate development.
[A]:
histamine H1