Table 3.

Overview of lysine’s antinociceptive experiments [55,56,57,58].

Model	Animal	Lysine Dose	Effect	Notes
Formalin Test	Rats	0.5 or 2 g/kg (s.c.)	↓ second-phase paw licking	Pain is reduced without affecting movement
c-Fos Neuron Activity	Rats (spinal cord)	0.5 or 2 g/kg (s.c.)	↓ active pain neurons (c-Fos)	Indicates reduced pain signals in the spinal cord
Acetic Acid Writhing	Mice	1 g/kg (i.p.) (intraperitoneal)	Writhing is completely suppressed	Lysine blocked pain caused by acid injection
Interaction with L-Arginine	Mice	L-Arginine 3 g/kg i.p. (intraperitoneal)	Blocked lysine’s effect	Suggests nitric oxide (NO) involvement
ADMA Interaction (NO Inhibitor)	Rats	ADMA before lysine (i.v.) infusion	Reversed lysine’s effect	Further confirms that the NO pathway plays a role
Multiple-Dose Testing	Rats	0.1–5 g/kg (p.o.) (oral gavage)	5 g/kg reduced writhing significantly	Especially after 24 h of acetic acid injection