Perspectivas de Comunicación Estratégica derivadas de la Teoría de Sistemas

Tissue from three animals was examined 2 weeks after axotomy of n.sartorius. Both ipsilateral and contralateral motoneurones showed large elevations in MBL for nNOS in the motor group giving rise to the n.sartorius (MBL = 5.18 ipsilaterally and 5.16 contralaterally), in comparison with normal motoneurones of the fourth lumbar segment (MBL = 3.95) (see Fig. 4 .2 .1 -7 ). These elevations were significant according to Dunnett’s T3 (p. < .0 0 1 ). The MBL of the sartorius motor group 2 weeks after n.sartorius axotomy was also significantly higher than the MBL of ON and VL 2 weeks after pudendal axotomy (p < .001). This is a reversal of the usual relationship between these cell groups, where normal sacral motoneurones have a significantly higher MBL than lumbar (see Chapter 3). Normal Ipsilateral Sart Contralateral Sart Ipsilateral Iliacus Lumbar Moto­ neurones Contralateral Iliacus

F igure 4 .2 .1 -7 . G ra p h to s h o w M B L o f n N O S -IR for th e m o to n e u ro n e s o f th e fou rth lu m b a r s e g m e n t in no rm ality an d a fte r injury to th e sartoriu s n e rv e . N for e a c h m e a n v a lu e is sh o w n a t th e to p o f e a c h bar. B lue b ars = n o rm a l/u n o p e ra te d M B L s , red b ars = ip sila tera l M B L s , g re e n b a rs = c o n tra la te ra l M B L s . Error b a r re p re s e n ts S .E .M .

Meanwhile, as an internal control, the MBL was also calculated for an anatomically discrete motor group originating from the same segment, conforming in position to the motoneurone group which innervates m. iliacus.

Unlike the adjacent axotomised motoneurones innervating m. sartorius, the

motoneurones either ipsilateral (MBL = 4.1) or contralateral to the lesion (MBL = 4 .95), confirming a selective response in the axotomised sartorius neurones. Variability in staining on the contralateral side was high, however, and thus the contralateral iliacus motoneurones were also not different from axotomised sartorius motoneurones on that side of the cord. Lumbar distributions of motoneurones across bin locations can be seen graphically in figure 4 .2 .1 -8 and

std. D e v = 1 .4 8 M e a n = 4 .0 N = 1 7 5 .0 0 1.0 2 0 3 0 4.0 5 0 6.0 7.0 8 0 9.0 1.0 2 0 3.0 4.0 5.0 6 0 7.0 8 0 9.0 S td . D e v = 1 .3 0 M e a n = 5 .2 N = 1 1 8 .0 0 N o rm a l A dult L u m b a r M o to n e u ro n e s (L 4 ) Ip sila tera l S a rto riu s M o to r G ro u p

F igure 4 .2 .1 -8 . H is to g ra m s to s h o w the distribution of n N O S bin locations in L4 in no rm a lity and a fte r sartorius a xo to m y. B lue bars - no rm al m o to n e u ro n e s , red bars - ipsilateral to th e lesion , g re en bars - c o n tra la te ra l to th e lesion.

S td . D e v = .7 9 M e a n = 4.1 1.0 ZO 3 0 4 0 5 0 6 0 7 0 8.0 9 0 N = 4 7 .0 0 S td . D e v = 1 .4 5 M e a n = 5 .2 N = 1 0 5 .0 0 1.0 2 0 3.0 4.0 5.0 6 0 7 0 8.0 9.0

C o n tra la te ra l S a rto riu s M o to r G ro u o

S td. D e v = 1.81

Ip sila tera l Ilia cu s M o to r G ro u p

M e a n = 5 .0

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 N = 5 2 .0 0 C o n tra la te ra l Iliacus M o to r G ro u o

post-axotomy alterations are shown photographically in figure 4 .2 .1 -9 . 4.2.1.iii. Discussion

In the adult rat, axotomies of cervical nerves at distances of 8mm from the spinal cord are not associated with alterations in nNOS/NADPH-d whilst ventral root avulsion is (Wu et al, 1994a; Wu et al, 1994b; Wu, 1996; Gu et al, 1997). This has led to the concept that nNOS upregulation after axotomy is dependent on the proximity of the injury to the cell body, with more distal lesions unlikely to evoke a response. M eanwhile, motoneuronal elevations of nNOS/NADPH-d

T

iiiacué

sart

sart

iliacus

T T

ipsi

Figure 4.2.1-9. nNOS-IR in lumbar motoneurones

(arrowheads) after axotomy of the nerve innervating the sartorius (sart) muscle. Bars = lOO^im.

▼

are seen after axotomies at greater distances (~1 l-14m m ) from the cell body in adult rat brainstem motor nuclei (Yu, 1994; Yu, 1997; Kristensson et al, 1994) suggesting the possibility of segmental variability in sensitivity of nNOS regulation to axotomy. Transections in the present study were carried out at distances of ~ 100mm from the cord, and did evoke alterations in nNOS-ir possibly reflecting segmental and species differences, but also reflecting the sensitivity of our antibody which detects motoneuronal nNOS-ir in normality that is not detected by other laboratories.

The extent and duration of nNOS elevation has been found to correlate with the likelihood of subsequent neuronal cell death (Kristensson et al, 1994; Gu et al, 1997). For example there is a decline in NADFH-d levels by the second week after hypoglossal axotomy, motoneurones of which show lesser neuronal loss than other groups with protracted NADFH-d elevation (Kristensson et al, 1994). Two weeks after pudendal axotomy in the present study, decreases in nNOS were found, when persistent elevation was observed at the same time point after sartorius axotomy. The sacral decrease coincides with the time point at which elevated NADFH-d declines in axotomised hypoglossal motoneurones (Kristensson et al, 1994). Since this group of motoneurones are more resistant to the injury than other brainstem neurones, which display continuing elevations of nNOS up to at least 4 weeks after surgery, the mechanism underlying the delayed down-regulation of nNOS at this time point may be important in understanding differential susceptibilities to degenerative changes.

The reasons for suppression of the hypoglossal nNOS response are not clear, however, the decrease in pudendal nNOS-ir may be related to afferent signals conveying information about altered bladder function. An acute elevation of nNOS/NADFH-d in lumbosacral motoneurones has been previously noted up to the 2"^ day after urethral obstruction in the guinea pig (Zhou and Ling, 1997).

Afferent signals in response to bladder distension may be partially responsible for this increase, via both autonomic connections and descending signals from the pontine micturition centre, in an attempt to overcome outlet resistance by increasing the relaxing NO signal to the sphincter. If somatic regulation of nNOS is sensitive to afferent signals relating to chronic alterations in bladder function, it is equally likely that nNOS might be down - regulated in response to signals conveying a decrease in contractility of the external sphincter, such as is likely to occur after the loss of 50% of sphincter innervation caused by unilateral axotomy. Further investigation is required to understand more fully the regulation of nNOS in pudendal motoneurones in relation to bladder function.

Another feature of post-axotomy changes in nNOS-ir is the striking bilaterality of the response in the sartorius motor group, contrasting the unilateral decrease in axotomised ON. Bilateral elevations in NADFH-d have also been seen in lumbar motoneurones after knee joint immobilisation in guinea pigs (He et al, 1997). The unilaterality of sacral response contrasted with the bilaterality of lumbar motoneuronal alterations will be seen to be a recurring segmental difference in axotomy responses and will therefore be discussed in greater depth in Chapter 5.

4.2.2 CaN-A and CM CaN-A

4.2.2.i. Pudendal Nerve Axotomy

A large decrease from normal CaN-IR was observed in axotomised sacral motoneurones ipsilateral to the lesion (Fig. 4.2.2-1, overleaf). In confirmation of the qualitative observations, MBL for CaN-A was significantly decreased in ON on the side of the lesion one week after pudendal nerve axotomy (MBL = 3.2), and had begun to return to normal by the second week of recovery (MBL = 4 .2 , vs. normal MBL of 4.7)(See Fig. 4.2.2-2). These differences were only significant at one week in terms of both means (Dunnett’s T3, p < 001) and distributions (K-S Z = 2.95, p<.001), although a one-tailed t-test showed a marginal difference between ipsilateral (axotomised) and normal ON at the second week (t= 1.866, p <.05). At one week after injury, ipsilateral ON was also significantly lower in MBL than all other motoneurones measured (Dunnett’s T3, all p < .001) with the exception of normal VL, but including injured lumbar motoneurones significantly different from Z = 1.772, p = .004).

N o rm a l O N Ip sila tera l (1 Ip sila tera l (2 C o n tra la te ra l C o n tra la te ra l w e e k ) w e e k s ) (1 w e e k ) (2 w e e k s )

F ig u r e 4 .2 .2 2 . G ra p h to s h o w M B L o f C a N -IR for th e m o to n e u ro n e s o f O N in no rm ality an d a fte r injury to th e p u d e n d a l n e rv e . N fo r e a c h m e a n v a lu e is sh o w n a t th e top o f e a c h bar. B lue b a r = norm al M B L , red bars = ip sila tera l M B L s , g re e n b a rs = c o n tra la te ra l M B L s . E rro r b ars rep re s e n t S .E .M .

contra

ON

VL

>

ipsi

VL

ON

; ▼

Figure 4.2.2-1. Reduced CaN-IR in sacral motoneurones

(arrowheads) after pudendal axotomy. The ipsilateral

motoneurones are distinctly less IR at one week (e) and two weeks (b,c), than the contralateral

motoneurones (one week - (f); two weeks - (a,d)). To facilitate

visualisation, outlines have been given to motoneurones that are difficult to distinguish from the background, which is raised due to the localisation of the antigen within the surrounding fibres. Bars = 100pm. : ▼ ▼ ▲

ipsi

contra

/ i f ,

▼ ▼

ipsi

contra

std. D e v = 1.71 M e a n = 4 .7 10 2 0 30 4 0 5 0 8 0 70 8 0 9 0 N ~ 7 2 .0 0 N o rm a l A d u lt O N Fig u re 4 . 2 2 - 3 . H is to g ra m s to s h o w th e distribution o f C a N -A bin lo catio ns in O N in n o rm a lity an d a fte r p u d e n d a l a xo to m y. B lue b ars - no rm a l m o to n e u ro n e s , red b ars - ip sila tera l to th e le s io n , g re e n bars - c o n tra la te ra l to th e lesion.

I

S td . D e v = 1 .4 7 M e a n = 3 .2 1 0 2 0 3 0 4 0 5 0 8 0 7 0 8 0 9 0 N — 8 3 .0 0 Ip s ila te ra l O N - 1 W e e k S td . D e v = 2 .1 7 M e a n = 4.1 1 0 2 0 3 0 4 0 5 0 8 0 7 0 8 0 9 0 N — 6 6 .0 0 C o n tra la te ra l O N - 1 W e e k â 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 Ip sila tera l O N - 2 W e e k s S td . D e v = 1 .3 6 M e a n = 4 .2 N = 9 2 .0 0 1 0 2 0 3 0 4 0 5.0 6 0 7 0 8 0 9 0 S td . D e v = 1 .5 6 M e a n = 5.1 N = 6 1 .0 0 C o n tra la te ra l O N - 2 W e e k s

Distributions for normal and injured ON across the nine data bins are shown in figure 4.2.2-3.

The VL group was no different from the normal VL one week after pudendal axotomy in terms of MBL on either side of the cord, but by the second week the MBL was significantly higher bilaterally than at either one week or in normality (Dunnett’s T3, p = .003 ipsilaterally, p = .05 contralaterally). Contralaterally, the VL MBL was higher than that in the ipsilateral ON at both 1 and 2 weeks, and the ipsilateral VL MBL was higher than the ipsilateral MBL for ON two weeks post-operatively (Dunnett’s T3, P <.001). The time-dependent changes in the MBL are compared in Fig. 4.2.2-4. and distributions are shown in Fig. 4.2.2- 5.

F ig u r e 4 .2 2 -4 . G ra p h to s h o w M B L o f C a N -IR fo r th e m o to n e u ro n e s of V L in n o rm a lity a n d a fte r injury to th e pu d e n d a l n e rv e . N for e a c h m e a n v a lu e is s h o w n at th e top o f e a c h bar. B lue b a r = no rm al M B L , red b ars = ip silateral M B L s , g re e n b ars = c o n tra la te ra l M B L s . E rro r b ars re p re s e n t S .E .M .

1

_T

8 9

i

9 8 8 3

N orm al V L Ip sila tera l (1 Ip silateral ( 2 C o n tra la te ra l C o n tra la te ra l w e e k ) w e e k s ) (1 w e e k ) ( 2 w e e k s ) n — Std. D e v = std. D e v = 1 .3 5 1 .7 0 M e a n = 3 .9 1 M e a n = 3 .8

.J]

L

7 0 0 0 9 0 N = 1 0 7 .0 0 ,

0

bn.

7 0 a o 9 0 N = 8 9 .0 0 J

XI.

7 0 0 0 9 0 S td . D e v = 1.31 M e a n - 4 .8 N = 8 9 .0 0 N o rm a l A d u lt V L Ip s ila te ra l V L - 1 W e e k Ip s ila te ra l V L - 2 W e e k s Fig u re 4 .2 2 -5 . H is to g ra m s to s h o w th e distribution o f C a N -A bin locatio ns in V L in no rm ality a n d a fte r p u d e n d a l axo to m y. B lue b ars - no rm a l

m o to n e u ro n e s , red b ars - ip silateral to th e lesion , g re e n b ars - c o n tra la te ra l to the lesion. S td . D e v = 1 .3 5 M e a n = 4 . N = 8 3 .0 0 1 0 2 0 3 0 4 0 5 0 6.0 7 0 8 0 9 0 C o n tra la te ra l V L - 2 W e e k s S td . D e v = 1 .9 4 M e a n = 4 .6 N = 9 8 .0 0 C o n tra la te ra l V L - 1 W e e k

4.2.2.Ü. N. Sartorius Axoiomy

Post-axotomy changes in the lumbar cord were more subtle than those seen in the sacral cord after pudendal nerve axotomy (Fig. 4.2.2-6). Nevertheless, 2 weeks after axotomy, the MBL for the sartorius motor group was lower than for either normal lumbar motoneurones (MBL = 4.87) or the neighbouring neurones of the iliacus motor group (MBL = 5.5 bilaterally). This difference was

F ig u r e 4 .2 .2 -7 . G ra p h to s h o w M B L for th e L4 m o to n e u ro n e s in n o rm a lity a n d a fte r injury to the sartoriu s n e r v e .T h e N fo r e a c h m e a n v a lu e is sh o w n a t th e to p o f e a c h bar. B lue b a r = n o rm al M B L , red b ars = ip sila tera l M B L s , g re e n b ars = c o n tra la te ra l M B L s . E rro r b ars re p re s e n t S .E .M . S a rt. = sartoriu s.

most pronounced on the side of the cord contralateral to the lesioned nerve (contralateral sartorius MBL = 4.29, ipsilateral MBL = 4.59) (see Fig. 4.2.2-7). The only significant difference detected by the Dunnett’s T3 was between the contralateral sartorius motor group and other ipsilateral lumbar motoneurones from a slightly more rostral portion of L4 than the iliacus and sartorius nuclei, which had a higher MBL of 5.5. The Kolmogorov-Sniirnov Z-test also showed the axotomised sartorius group to be no differently distributed than normal lumbar motoneurones, although the ipsilateral sartorius motor group results were significantly more positively skewed in distribution than neighbouring

sart

GM

WM

ipsi

Figure 4.2 2-6. CaN-IR in lumbar motoneurones

(arrowheads) after axotomy of the nerve innervating the sartorius (sart) muscle.

Ipsilateral (a) and contralateral (c) motoneurones show a moderate decrease in staining compared to normal (b) sartorius motoneurones. Bars = 100pm.

sart

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 S td . D e v = 1.88 M e a n = 4 .9 N = 2 9 3 .0 0 N o rm a l L u m b a r M o to n e u ro n e s S td. D e v = 1 .8 2 M e a n = 4 .6 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 N = 6 9 .0 0

Ip sila tera l S a rto riu s M o to r G ro u p

S td . D e v = 1 .6 9 M e a n = 4 .3

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 N = 6 1 . 0 0

C o n tra la te ra l S a rto riu s M o to r G ro u p

F ig u re 4 .2 .2 -8 . H is to g ra m s to s h o w the distrib utio n o f C a N -A bin lo catio ns in L4 in n o rm a lity a n d a fte r p u d e n d a l a x o to m y . B lue b a rs - no rm al m o to n e u ro n e s , red b ars - ip s ila te ra l to th e le s io n , g re e n b ars - c o n tra la te ra l to th e lesion . S td . D e v = 2.02 M e a n = 5 .5 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 N = 5 3 .0 0 Ip sila tera l Ilia cu s M o to r G ro u p

S td . D e v = 1 .5 9 M e a n = 5 .5 N = 4 4 .0 0 0 2 0 3 0 4 0 5 0 6.0 7 0 8.0 9 0 C o n tra la te ra l Ilia cu s M o to r G ro u p

iliacus motoneurones on the same side of the cord (K-s Z = 1.794, p = .003)(for

In document Análisis de la movilidad sostenible en la Ciudad Universitaria de la BUAP 2014 2016 (página 47-51)