Sensory Neuronal Change after Intravesical Electrical Stimulation in Spinailized Rat

The clinical benefits of intravesical electrical stimulation (IVES) in patients with increased residual urine or reduced bladder capacity have been reported. However, studies on the underlying mechanism of IVES has been limited to the A delta afferent and parasympathetic neurons. This study investigated the changes in the calcitonin gene-related peptide (CGRP), substance P (SP), and nitric oxide synthase (NOS) expression in the thoracolumbar and lumbosacral dorsal root ganglia (DRG) of spinalized rats to determine the effect of IVES on the C fiber afferent nerve. Forty Sprague-Dawley rats were divided into normal controls (n=10); IVES treated normal rats (n=10), spinalized rats (n=10), and IVES treated spinalized rats (n=10). IVES was performed for 2 weeks (5 days a week). IVES was started 3 weeks after spinalization in the spinalized animals. All animals had the DRG removed at the thoracolumbar (T13-L2) and lumbosacral (L5-S1) level. Changes in the CGRP, SP and n-NOS levels at the DRG were measured by western-blot analysis. The relative density of the CGRP and SP following spinalization was significantly higher compared to the controls in both the T13-L2 and L5-S1 DRG. However, IVES in the spinalized rat significantly decreased the relative density of the CGRP and SP compared to the rats with spinalization alone. A significant increase in the relative density of n-NOS was detected in the L5-S1 DRG following spinalization. However, the density of n-NOS was significantly lower after IVES in both the T13-L2 and L5-S1 DRGs. In conclusion, IVES significantly reduced the CGRP, SP and n-NOS levels in the DRG of spinalized rats. CGRP, SP and n-NOS are the main factors that contribute to the hyperexcitability of the micturition reflex after spinal cord injury. These results suggest that the bladder C fiber afferent is also involved in modulating the micturition reflex by IVES.

Substance P in rectal mucosa of children with chronic constipation

Niveles de Substancia P fueron determinados por radioinmunoassay en la mucosa rectal de 17 niños con constipación, idiopática crónica y comparados con la de 9 ninõs sin constipación. En el grupo de niños con constipación, los niveles de Sustancia P fueron menores que aquellos de los controles: 47,6+-11 vs. 79,4+-11 pg/mg de peso húmero de tejido respectivamente (la diferencia no obtuvo significación estadística). Niveles de Sustancia P en la mucosa rectal de niños con soiling (11/17) no fueron diferentes de los niveles en niños constipados sin soiling (46,0+-13 vs. 50,5+-19). En niños con constipación, los niveles de Sustancia P no varían de acuerdo a la edad o la duración de síntomas. Los niveles de Sustancia P en la mucosa rectal de niños controles (sin constipación) fueron similares a aquellos que previamente observamos en adultos normales, y los niveles en niños constipados fueron intermediarios entre estos niveles normales y los de adultos constipados. Estas observaciones sugieren un problema de motilidad como factor importante en la patogenesis de la constipación crónica en niños.

Studies on the changes of c-fos protein in spinal cord and neurotransmitter in dorsal root ganglion of the rat with an experimental peripheral neuropathy

Animal models for human chronic pain syndromes have been developed and widely used for pain research. One of these neuropathic pain models by Kim and Chung (1992) has many advantages for operation and pain elicitation. In this neuropathic model we have examined the c-fos protein, substance P, CGRP immunoreactivity in dorsal root ganglia and dorsal horn. 50 Sprague-Dawley rats were used for this study. L5 and L6 spinal nerves were ligated tightly to produce the neuropathic pain model. After 2, 4, 8, 16, and 24 hours and 1 week of surgery, rats were anesthetized and sacrificed by perfusion. After confirmation of the roots transected by the surgery, the L5 and L6 dorsal root ganglions and spinal cord were removed and processed for immunohistochemistry. All tissue sections were immunohistochemically stained for substance P, CGRP and c-fos using the peroxidase-antiperoxidase (PAP) method. The number of immunostained substance P and CGRP dorsal root ganglion cells and c-fos immunoreactive dorsal horn cells were counted and analyzed statistically with Mann-Whitney U test. The results are as follows. The number of c-fos protein immunoreactive neurons in the superficial layer of dorsal horn were increased markedly 2 hours after operation, and gradually decreased to normal level 1 week after operation. The number of c-fos protein immunoreactive neurons in the deep layer of the dorsal horn gradually increased to a peak 24 hours after operation, then decreased to the normal level 1 week after operation. The number of substance P and CGRP immunoreactive L5 and L6 dorsal root ganglion neurons were decreased markedly 1 week after the pain model operation. In conclusion, after neuropathic pain model operation, c-fos proteins were immediately expressed in the superficial layer of spinal dorsal horn, thereafter c-fos proteins in the deep layer of spinal dorsal horn were expressed. CGRP and substance P immunoreactive neurons in DRG were decreased markedly 1 week after neuropathic pain model operation. These decrements do not coincide with the other chronic pain models, which show great increases in these pain transmitting substances. Therefore, the relationship between pain and c-fos, SP and CGRP should be investigated further.

NMR and molecular dynamics studies of tachykinins: conformation of the C-terminal pentapeptide of substance P(SP7-11).

Substance P belongs to the tachykinin family of neuropeptides which exhibit diverse pharmacological activity. The conformation of Phe1-Phe2-Gly3-Leu4-Met5-NH2 the C-terminal pentapeptide of substance P (SP7-11) has been studied by NMR and molecular dynamics (MD) methods. NMR studies were carried out both in DMSO-d6 and 95% H2O. Based on the observed chemical shifts, 3JNH alpha coupling constants, temperature coefficients of chemical shifts of NH resonances and the pattern of inter- and intraresidue NOE's, a predominantly extended backbone conformation has been deduced for the peptide in both DMSO and H2O. MD calculations carried out in vacuo indicate that the global minimum energy conformation of the molecule is folded with an intramolecular hydrogen bond between the protonated N-terminal and the C-terminal CONH2 group. The simulation shows that beta-turns are energetically unfavourable, while alpha-helices are seen to be unstable for the peptide. gamma-Bends at either Gly3 or Leu4 are the most preferred ones. Simulations carried out in DMSO as well as in water show a preference for a nearly extended conformation.