Table 2.

Axonal transport deficit in pmn mice

Strain of mouse	pmn (16 d)	Control (16 d)	pmn (29 d)	Control (29 d)
Nerve length (mm)	23.9  ± 0.3	24.3  ± 0.2	27.9  ± 0.2*	32.1  ± 0.2
	(n = 4)	(n = 4)	(n = 5)	(n = 6)
Rate of labeling (mm/day)	n.d.	n.d.	37.2	64
Gastrocnemius weight (mg)	18.62  ± 1.4**	30.8  ± 1.3.5	19.02  ± 1.2*	51.7  ± 5.7
	(n = 5)	(n = 6)	(n = 7)	(n = 6)
Maximum of motoneurons at 6 d, 0.5% Fast blue	291  ± 25	509  ± 24	262  ± 11	483  ± 34
	(n = 4)	(n = 3)	(n = 4)	(n = 4)
Maximum of motoneurons at 6 d, 1% Fast blue	n.d.	n.d.	280  ± 26	n.d.
			(n = 3)
% of maximum at 48 hr	51.2  ± 15*	89.0  ± 7.3	47.9  ± 2.7*	73.7  ± 12
% of maximum at 96 hr	n.d.	n.d.	90.4  ± 14.8	93.6  ± 10.5

pmn mice show deficits in axonal retrotransport as soon as the first clinical symptoms appear. The difference in motoneuron retrolabeling between controls and pmn mice was compared with nerve length and muscle weight. At day 16, there was no significant difference in the length of the sciatic nerve; however, the percentage of motoneurons labeled at 48 hr was significantly lower in pmn than in controls. At day 29, despite the shorter sciatic nerve in pmn, the percentage of labeled motoneurons was lower than in controls. The rate of labeling has been calculated by dividing the distance (nerve length) by the time necessary to obtain the first motoneurons labeled (12 hr for controls, 18 hr for pmn mice). n, Number of animals in each group; n.d., not determined.

*p < 0.001; **p < 0.01.