However there are also nicotinic receptors, as well as M1 and M5 (Soto et al, 2013).
In the CNS, the N or P/Q type are the ones that participate in neurotransmitter release.
Glycine receptors colocate with GABA receptors (Soto et al, 2312).
The circuitry by which several other neurotransmitters affect vestibular responses is less well understood.
Diphenidol (Vontrol), is also an anticholinergic, although little used in the US.
There are also a host of other neurotransmitters which modulate function.There is some equivocal data suggesting that serotonin agonists such as are used for migraine can prevent motion sickness.Cannabinoid receptors are present in the central vestibular circuitry, but their action is presently unclear (Smith, 2006) Vestibular suppressant and antiemetic drugs are the mainstay of treatment of vertigo.Examples are meclizine, dimenhydrinate, and diphenhydramine. Agents with central anticholinergic effects are most important in treating vertigo, since anticholinergic drugs that do not cross the blood-brain barrier are ineffective in controlling motion sickness (Takeda et al, 1989).Unlike antihistamines which will be discussed subsequently, pure anticholinergics are ineffective if administered after symptoms have already appeared.