What is strychnine? what symptoms does it cause?

Trychnine prevents the proper operation of the chemical that controls nerve signals to the muscles. The chemical controlling nerve signals works like the body's “off switch” for muscles. When this “off switch” does not work correctly, muscles throughout the body have severe, painful spasms.

Strychnine is a highly toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents.   
Agitation

Apprehension or fear

Ability to be easily startled

RestlessnessPainful muscle spasms possibly leading to fever and to kidney and liver injury

Uncontrollable arching of the neck and back

Rigid arms and legs

Jaw tightness

Muscle pain and soreness

Difficulty breathing

Dark urineInitial consciousness and awareness of symptoms

People exposed to high doses of strychnine may have the following signs and symptoms within the first 15 to 30 minutes of exposure:Respiratory failure (inability to breathe), possibly leading to death

Brain death