with the plants tells how and for what they are to be used.
The other type of AChR is activated by the molecule muscarine,
identified from and named after the colorful mushroom Amanita
muscaria.=~
HO 3 __
\7
ANN 0
0
Muscarine O
AtropineReceptors activated by muscarine are antagonized by the molecule at-
ropine, identified from and named after the plant Atropa belladonna.
This type of AChR is named the muscarinic AChR (mAChR) and is
found in the parasympathetic neural connections with target organs,
as well as in the brain. The mAChR is now recognized as a G-protein-
coupled receptor.
The molecular structure diagrams of these drugs remind us that
all these chemicals are composed of carbon, nitrogen, oxygen, and
hydrogen atoms, hooked together by covalent chemical bonds into
specific geometric shapes. The different shapes of the molecules con-
fer upon them their differing pharmacologic properties. Note that
tubocurarine and muscarine both have positive charges and will col-
lect water molecules that prevent them from crossing the blood-brain
barrier. Nicotine and atropine are hydrophobic molecules that readily
cross the blood-brain barrier and have effects on brain neurons.
Drugs that enter the brain and impact brain function may produce
effects on mental experience—thoughts, feelings, and perceptions.
Such drugs are called psychoactive—they affect the mind or psyche.