Table 1. Somatic signs of morphine withdrawal in Narp KO and WT mice.

Three days after morphine pump implantation, Narp KO and WT mice were administered a single dose of saline in a novel environment. The following day mice were administered a single dose of naltrexone 250ug/kg sc in the same chamber and were monitored for 30 minutes. The table shows the mean number of somatic morphine withdrawal signs for each genotype after saline and naltrexone administrations

	Genotype	Injection	Mean±SE	Effect1
Jumps equally in both WT and KO mice	WT	Naltrexone	29.3±5.9	Naltrexone increased
		Saline	0.0±0.0
	KO	Naltrexone	32.8±8.3
		Saline	0.0±0.0
Diarrhoea equally in both WT and KO mice	WT	Naltrexone	7.0±0.7	Naltrexone increased
		Saline	0.0±0.0
	KO	Naltrexone	8.1±1.2
		Saline	0.0±0.0
Activity equally in both WT and KO mice	WT	Naltrexone	57.6±16.3	Naltrexone decreased
		Saline	103.0±13.8
	KO	Naltrexone	54.7±4.6
		Saline	99.0±12.1
Nose-wipe equally in both WT and KO mice	WT	Naltrexone	45.3±16.3	Naltrexone increased
		Saline	4.3±1.8
	KO	Naltrexone	37.7±10.1
		Saline	0.9±0.5
Tremors or genotype	WT	Naltrexone	1.7±0.5	No effects of naltrexone
		Saline	0.0±0.0
	KO	Naltrexone	3.0±2.0
		Saline	0.0±0.0
Grooming levels in both WT and KO mice + overall higher levels in KO mice	WT	Naltrexone	0.0±0.0	Naltrexone decreased
		Saline	8.7±2.1
	KO	Naltrexone	1.6±0.7
		Saline	14.4±1.6
Digging levels in both WT and KO mice + overall lower levels in KO mice	WT	Naltrexone	2.8±1.7	Naltrexone decreased
		Saline	28.7±6.3
	KO	Naltrexone	3.9±2
		Saline	12.4±4.6
Rearing or genotype	WT	Naltrexone	21.2±2.9	No effects of naltrexone
		Saline	35.5±10.1
	KO	Naltrexone	33.3±13.3
		Saline	26.6±4.4
Stretches or genotype	WT	Naltrexone	0.0±0.0	No effects of naltrexone
		Saline	0.3±0.3
	KO	Naltrexone	0.0±0.0
		Saline	0.4±−0.4

Note:

¹Based on 2-way ANOVA that included Injection (Naltrexone versus Saline) and Genotype (WT versus KO) as within and between comparisons. Significant when p <0.05.