Table 1.

The experimental and control groups

Groups	Experimental and control groups	Number of animals
Control	DMSO (i.p.) + saline (s.c.) (single dose)	6
Single dose ferrostatin-1	1 mg/kg ferrostatin-1 (i.p.) + saline (s.c.)	6
Single dose morphine	DMSO (i.p.) + 5 mg/kg morphine (s.c.)	6
Single dose morphine + ferrostatin-1	1 mg/kg ferrostatin-1 (i.p.) + 5 mg/kg morphine (s.c.)	6
Morphine tolerance	DMSO (i.p.) + 10 mg/kg morphine tolerance (s.c.) twice daily for five days. On the sixth day, the rats were administered the optimal analgesic dose of morphine (5 mg/kg)	6
Morphine tolerance + ferrostatin-1	1 mg/kg ferrostatin-1 (i.p.) + 10 mg/kg morphine (s.c.) twice daily for five days. On the sixth day, the rats were administered the optimal analgesic dose of morphine (5 mg/kg)	6

DMSO: dimethyl sulfoxide, i.p.: intraperitoneally, s.c.: subcutaneously.