vasoactive-intestinal-peptide and Spinal-Cord-Injuries

Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are expressed in the neural pathways regulating the lower urinary tract. VIP-immunoreactivity (IR) is present in afferent and autonomic efferent neurons innervating the bladder and urethra, whereas PACAP-IR is present primarily in afferent neurons. Exogenously applied VIP relaxes bladder and urethral smooth muscle and excites parasympathetic neurons in bladder ganglia. PACAP relaxes bladder and urethral smooth muscle in some species (pig) but excites the smooth muscle in other species (mouse). Intrathecal administration of VIP in cats with an intact spinal cord suppresses reflex bladder activity, but intrathecal administration of VIP or PACAP in rats enhances bladder activity and suppresses urethral sphincter activity. PACAP has presynaptic facilitatory effects and direct excitatory effects on lumbosacral parasympathetic preganglionic neurons. Chronic spinal cord transection produces an expansion of VIP-IR (cats) and PACAP-IR (rats) in primary afferent axons in the lumbosacral spinal cord and unmasks spinal excitatory effects of VIP on bladder reflexes in cats. Intrathecal administration of PACAP6-38, a PAC1 receptor antagonist, reduces bladder hyperactivity in chronic spinal-cord-injured rats. These observations raise the possibility that VIP or PACAP have a role in the control of normal or abnormal voiding.

Topics: Animals; Muscle, Smooth; Neural Pathways; Pituitary Adenylate Cyclase-Activating Polypeptide; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; Reflex; Spinal Cord; Spinal Cord Injuries; Urinary Tract; Vasoactive Intestinal Peptide

The lower urinary tract has two main functions, the storage and periodic expulsion of urine, which are regulated by a complex neural control system in the brain and lumbosacral spinal cord. This neural system coordinates the activity of two functional units in the lower urinary tract: (1) a reservoir (the urinary bladder) and (2) an outlet (consisting of bladder neck, urethra and striated muscles of the pelvic floor). During urine storage the outlet is closed and the bladder is quiescent, thereby maintaining a low intravesical pressure over a wide range of bladder volumes. During micturition the outlet relaxes and the bladder contracts to promote the release of urine. This reciprocal relationship between bladder and outlet is generated by visceral reflex circuits, some of which are under voluntary control. Experimental studies in animals indicate that the micturition reflex is mediated by a spinobulbospinal pathway passing through a coordination center (the pontine micturition center) located in the rostral brainstem. This reflex pathway is in turn modulated by higher centers in the cerebral cortex that are presumably involved in the voluntary control of micturition. Spinal cord injury at cervical or thoracic levels disrupts voluntary control of voiding as well as the normal reflex pathways that coordinate bladder and sphincter functions. Following spinal cord injury, the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. Studies in animals indicate that the recovery of bladder function after spinal cord injury is dependent in part on plasticity of bladder afferent pathways and the unmasking of reflexes triggered by capsaicin-sensitive C-fiber bladder afferent neurons. The plasticity is associated with changes in the properties of ion channels and electrical excitability of afferent neurons, and appears to be mediated in part by neurotrophic factors released in the spinal cord and the peripheral target organs.

Topics: Adrenergic Fibers; Afferent Pathways; Animals; Brain; Efferent Pathways; Glutamic Acid; Humans; Interneurons; Nerve Growth Factors; Pituitary Adenylate Cyclase-Activating Polypeptide; Potassium Channels; Reflex; Sodium Channels; Spinal Cord; Spinal Cord Injuries; Synaptic Transmission; Tachykinins; Urinary Bladder; Urination Disorders; Vasoactive Intestinal Peptide

Previous evidence shows that rapid changes occur in the brain following spinal cord injury (SCI). Here, we interrogated the expression of the neuropeptides pituitary adenylyl cyclase-activating peptide (PACAP), vasoactive intestinal peptides (VIP), and their binding receptors in the rat brain 24 h following SCI. Female Sprague-Dawley rats underwent thoracic laminectomy; half of the rats received a mild contusion injury at the level of the T10 vertebrate (SCI group); the other half underwent sham surgery (sham group). Twenty-four hours post-surgery, the hypothalamus, thalamus, amygdala, hippocampus (dorsal and ventral), prefrontal cortex, and periaqueductal gray were collected. PACAP, VIP, PAC1, VPAC1, and VPAC2 mRNA and protein levels were measured by real-time quantitative polymerase chain reaction and Western blot. In SCI rats, PACAP expression was increased in the hypothalamus (104-141% vs sham) and amygdala (138-350%), but downregulated in the thalamus (35-95%) and periaqueductal gray (58-68%). VIP expression was increased only in the thalamus (175-385%), with a reduction in the amygdala (51-68%), hippocampus (40-75%), and periaqueductal gray (74-76%). The expression of the PAC1 receptor was the least disturbed by SCI, with decrease expression in the ventral hippocampus (63-68%) only. The expression levels of VPAC1 and VPAC2 receptors were globally reduced, with more prominent reductions of VPAC1 vs VPAC2 in the amygdala (21-70%) and ventral hippocampus (72-75%). In addition, VPAC1 downregulation also extended to the dorsal hippocampus (69-70%). These findings demonstrate that as early as 24 h post-SCI, there are region-specific disruptions of PACAP, VIP, and related receptor transcript and protein levels in supraspinal regions controlling higher cognitive functions.

Topics: Animals; Brain; Female; Pituitary Adenylate Cyclase-Activating Polypeptide; Rats; Rats, Sprague-Dawley; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; Receptors, Pituitary Hormone; Receptors, Vasoactive Intestinal Peptide, Type II; Receptors, Vasoactive Intestinal Polypeptide, Type I; Spinal Cord Injuries; Vasoactive Intestinal Peptide

To study the effects of sacral nerve root electrostimulation (SNS) on the colon function and its mechanisms in rats with spinal cord injury (SCI).. One hundred and four Wistar rats were divided into three groups: A, B and C. A group ( n = 24) was divided into three subgroups (n = 8) for studying the bioelectricity: Normal group (NG), SCI group (SCI) and SCI group with SNS(SNS); B group( n = 24) was divided into three subgroups( n = 8) for studying the colon motility: NG, SCI and SNS. C group( n = 56) were divided into three groups for studying the change of morphology and neurotransmitters(SP and VIP): NG (n = 8), SCI (n = 24), and SNS (n = 24) . In SCI and SNS, included of three subgroups: 24, 48, 72 h after spinal cord injury (n = 8).. In SCI group, the activity of bioelectricity in proximal and distal colon was reduced; the colon motility was lessened, and colon mucosa appeared different degree of damage; cell-cell connections between intestinal epithelial cells were destroyed. The expressions of substance P(SP) and vasoactive intestinal peptide (VIP) in colon were decreased obviously. SNS was found to activate the bioelectricity, promote the colon motility, improve the intestinal mucosal, and increase the expressions of SP and VIP. Conclusion: SNS can activate the peristalsis, rehabilitate the motility of denervated colon, protection of the intestinal mechanical barrier between intestinal epithelial cells and tight junction, rebuild the colon function through activating the bioelectricity and increase the expressions of SP and VIP.

Topics: Animals; Colon; Electric Stimulation Therapy; Epithelial Cells; Intestinal Mucosa; Lumbosacral Region; Neurotransmitter Agents; Rats; Rats, Wistar; Spinal Cord Injuries; Substance P; Vasoactive Intestinal Peptide

To observe the altered expressions of neuropeptide Y, substance P and vasoactive intestinal peptide in detrusor of SD rats after spinal cord injury and explore the relationship of the above neuropeptides and neurogenic bladder after spine cord injury.. Twenty male clean-grade SD rats, aged 6 weeks, were selected and randomized into spinal cord injury group (n = 10) and control group (n = 10). Rats in spinal cord injury group were smashed at T10 to cause spinal cord incomplete injury model by the weight drop method while laminectomy alone without smashing was administered in control group. At Week 1 post-operation, all rats were assessed by the maximum bladder capacity, bladder compliance and detrusor pressure for the confirmation of spastic bladder. And all detrusor specimens were marked with argentation and immunohistochemistry for the analyses of nerve fibers, neuropeptide Y, substance P and vasoactive intestinal peptide. The results were evaluated with semiquantitative method to observe the contents of nerve fiber and neuropeptides.. At Week 1 post-operation, the mean maximum bladder compactly, mean maximum detrusor pressure and mean compliance in SCI rats was 0.71 ± 0.24 ml, 32.27 ± 3.12 cm H2O and 0.020 ± 0.009 ml/cm H2O versus 2.0 ± 0.4 ml, 21.0 ± 3.0 cm H2O and 0.090 ± 0.020 ml/cm H2O in normal control group respectively. And the differences were statistically significant (P < 0.01). Meanwhile, the mean content of nerve fibers of neurogenic bladder decreased markedly than that of normal control group (2.58 ± 0.13 vs 5.65 ± 0.26). As compared with the normal control group, the expressions of neuropeptide Y, substance P and vasoactive intestinal peptide (mean integrated optical density: 3.2 ± 0.5, 1.7 ± 0.4 and 2.1 ± 0.4 respectively) decreased dramatically in SCI rats. And the differences were statistically significant (P < 0.01).. The number of nerve fibers and the content of neuropeptides significantly decrease in neurogenic bladder after spinal cord injury in rats. The reduction of neuropeptides may be correlated with the formation of neurogenic bladder after spinal cord injury.

Topics: Animals; Male; Neuropeptide Y; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Substance P; Urinary Bladder; Urinary Bladder, Neurogenic; Vasoactive Intestinal Peptide

To find more evidence for mechanism and treatment of pelvic floor dysfunction (PFD), we observed muscle tension and neuropeptide of pelvic floor muscle in rats after spinal cord injury (SCI).. 30 SD adult female rats were randomly divided into suprasacral cord injury group (SS), spinal cord injury at or below the sacral level group (SC) and normal group; 4 weeks after transection of spinal cord, muscle tension including compliance and excitability, and neuropeptide were observed.. Compliances in SC group, SS group and normal group were (16.23 +/- 4.46) g, (13.44 +/- 4.15) g and (14.46 +/- 5.61) g respectively, there were no difference among them (P > 0.05), but their excitability under best initial length were (0.35 +/- 0.19) g, (2.80 +/- 2.12) g and (7.75 +/- 2.98) g according to SC, SS and normal group, excitability under prolonged length were (2.61 +/- 0.73) g, (4.67 +/- 1.16) g, (14.86 +/- 3.79) g respectively. SC and SS group were both lower than normal group (P < 0.05), meanwhile SC group was much lower than SS group (P < 0.05); neuropeptide Y and vasoactive intestinal peptide in SS and SC group were significant lower than normal group, and these two neuropeptides in SC were much lower than SS group (P < 0.05).. Muscular excitability and neuropeptide in pelvic floor muscle are decreased obviously at both below and above sacral cord injury, SCI below sacral cord makes much lower level excitability and neuropeptide. The abnormality in pelvic floor muscle after SCI should be emphasized.

Topics: Animals; Disease Models, Animal; Female; Muscle Tonus; Neuropeptides; Pelvic Floor; Random Allocation; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Vasoactive Intestinal Peptide

Gastrointestinal (GI) abnormalities resulting from spinal cord injury (SCI) are challenging disorders that have not been examined experimentally using clinically relevant models. In this study, female Sprague-Dawley rats (n=5/groupx4: T10-T11 contusion, laminectomy, or naïve) were fasted for 24 h before being submitted to dye recovery assays (Phenol Red solution, 1.5 ml/rat; per oral) on GI emptying/transiting at 48 h or 4 weeks postinjury (p.i.). Compared with controls, SCI significantly increased dye recovery rate (DRR, determined by spectrophotometry) in the duodenum (+84.6%) and stomach (+32.6%), but decreased it in the jejunum (-64.1% and -49.5%) and ileum (-73.6% and -70.1%) at 48 h and 4 weeks p.i., respectively (P

Topics: Animals; Female; Gastrointestinal Diseases; Gastrointestinal Tract; Gastrointestinal Transit; Immunohistochemistry; Membrane Potentials; Nitric Oxide Synthase Type I; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Vasoactive Intestinal Peptide

Tumor necrosis factor-alpha (TNF-alpha) production accompanies CNS insults of all kinds. Because the neuropeptide vasoactive intestinal peptide (VIP) and the structurally related peptide pituitary adenylyl cyclase-activating polypeptide (PACAP) have potent anti-inflammatory effects in the periphery, we investigated whether these effects extend to the CNS. TNF-alpha mRNA was induced within 2 hr after rat spinal cord transection, and its upregulation was suppressed by a synthetic VIP receptor agonist. Cultured rat microglia were used to examine the mechanisms underlying this inhibition because microglia are the likely source of TNF-alpha in injured CNS. In culture, increases in TNF-alpha mRNA resulting from lipopolysaccharide (LPS) stimulation were reduced significantly by 10(-7) m VIP and completely eliminated by PACAP at the same concentration. TNF-alpha protein levels were reduced 90% by VIP or PACAP at 10(-7) m. An antagonist of VPAC(1) receptors blocked the action of VIP and PACAP, and a PAC(1) antagonist blocked the action of PACAP. A direct demonstration of VIP binding on microglia and the existence of mRNAs for VPAC(1) and PAC(1) (but not VPAC(2)) receptors argue for a receptor-mediated effect. The action of VIP is cAMP-mediated because (1) activation of cAMP by forskolin mimics the action; (2) PKA inhibition by H89 reverses the neuropeptide-induced inhibition; and (3) the lipophilic neuropeptide mimic, stearyl-norleucine(17) VIP (SNV), which does not use a cAMP-mediated pathway, fails to duplicate the inhibition. We conclude that VIP and PACAP inhibit the production of TNF-alpha from activated microglia by a cAMP-dependent pathway.

Topics: Animals; Cells, Cultured; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Enzyme Inhibitors; Gene Expression; Isoquinolines; Lipopolysaccharides; Microglia; Neurons; Neuropeptides; Pituitary Adenylate Cyclase-Activating Polypeptide; Rats; Rats, Sprague-Dawley; Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; Receptors, Pituitary Hormone; Receptors, Vasoactive Intestinal Peptide; Receptors, Vasoactive Intestinal Polypeptide, Type I; RNA, Messenger; Signal Transduction; Spinal Cord Injuries; Sulfonamides; Tumor Necrosis Factor-alpha; Vasoactive Intestinal Peptide

The bladder receives an extensive nerve supply that is predominantly cholinergic, but several putative transmitters are present, some of which are colocalized. Previous studies have shown increased levels of sensory nerves, reduced inhibitory transmitters, and structural and functional changes in the excitatory input in unstable bladder conditions. The present study compared the end-organ nerve supply to the bladder in spinal cord injury (SCI) with uninjured controls. Acetylcholinesterase histochemistry and double-label immunofluorescence were used to investigate neurotransmitter content, with confocal laser scanning microscopy to assess colocalization. Organ bath studies provided functional correlates for the structural changes in the excitatory innervation. Control samples had dense innervation of the detrusor containing a diverse range of transmitters. Hyperreflexic SCI samples showed patchy denervation, and areflexic SCI samples were diffusely denervated. Vasoactive intestinal polypeptide-, neuropeptide Y-, neuronal nitric oxide synthase-, and galanin-immunoreactive nerve fibers were reduced from frequent or moderately frequent to infrequent or very infrequent in SCI. Calcitonin gene-related peptide-immunoreactive fibers were infrequent in controls and SCI samples. Patterns of colocalization were unchanged, but significantly fewer fibers expressed more than one transmitter. The subepithelial plexus was markedly reduced and several of the smaller coarse nerve trunks showed no immunoreactivity to the transmitters assessed. There was no reduction in sensitivity to electrical field stimulation of intrinsic nerves in SCI, but the maximum force generated by each milligram of bladder tissue and the peak force as a proportion of the maximum carbachol contraction were significantly reduced and the responses were protracted. There was no significant functional atropine-resistant neuromuscular transmission in controls or SCI. The reported findings have clinical implications in the management of chronic SCI and development of new treatments.

Topics: Adult; Calcitonin Gene-Related Peptide; Carbachol; Denervation; Electric Stimulation; Female; Humans; In Vitro Techniques; Male; Middle Aged; Muscle, Smooth; Neuropeptide Y; Spinal Cord Injuries; Urinary Bladder; Vasoactive Intestinal Peptide

Micturition in cats and rats with an intact neuraxis is dependent upon a spinobulbospinal reflex activated by A delta bladder afferents. This report describes changes in micturition reflexes 2 h to 14 weeks following spinal cord transection at the lower thoracic level. In acute spinal cats micturition reflexes were blocked, however, several weeks after transection, a long latency (180-200 ms) spinal reflex could be activated by C-fiber bladder afferents. This reflex was blocked by capsaicin in doses (20-30 mg/kg, s.c.) that did not affect micturition reflexes in intact cats. Micturition reflexes were unmasked in acute spinal and facilitated in chronic spinal cats by naloxone, an opioid antagonist. Spinal neurons and axons containing opioid peptides were more prominent below the level of transection in chronic spinal cats. VIP, a putative neurotransmitter in C-fiber bladder afferents, inhibited micturition reflexes when injected intrathecally (2-10 micrograms) in intact cats but facilitated micturition reflexes in spinal cats (doses 0.1-1 micrograms, i.t.). VIP-containing C-fiber afferent projections to lamina I of the sacral spinal cord expanded in spinal cats. Thus VIP afferents may have an important role in the recovery of bladder reflexes after spinal injury. Paraplegic animals also exhibit bladder-sphincter dyssynergia, which causes functional outlet obstruction. Studies in rats have revealed that outlet obstruction induced by partial urethral ligation facilitates spinal micturition reflex pathways and causes an expansion of HRP-labelled bladder afferent projections in the spinal cord. These findings raise the possibility that the alterations in central reflex connections in paraplegic animals may be induced in part by changes in peripheral afferent input secondary to outlet obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Afferent Pathways; Animals; Capsaicin; Cats; Electric Stimulation; Female; Male; Muscle, Smooth; Naloxone; Rats; Reflex; Spinal Cord Injuries; Urinary Bladder; Vasoactive Intestinal Peptide

The urethras from 1 patient with cervical (C1-2) and 2 patients with thoracic (T10) spinal cord lesions were studied histochemically and immunohistochemically for adrenergic and vasoactive intestinal polypeptide-immunoreactive nerves. Dense vasoactive intestinal polypeptide-immunoreactive but not adrenergic nerves were found in the urethral smooth muscle, around the blood vessels and at the base of the mucosa in the patients with thoracic lesions. In contrast, adrenergic but not vasoactive intestinal polypeptide-immunoreactive nerves were found associated with the smooth muscle of the urethra and around the blood vessels in the patient with a cervical lesion. In patients with cervical or thoracic lesions neither adrenergic nor vasoactive intestinal polypeptide-immunoreactive nerves were found around striated muscle fibers of the intrinsic external urethral sphincter. The results are discussed in relation to the possible function of these nerves in the urethra of patients with autonomic dysreflexia and detrusor-sphincter dyssynergia.

Topics: Adult; Autonomic Nervous System Diseases; Catecholamines; Cervical Vertebrae; Humans; Male; Middle Aged; Reflex, Abnormal; Spinal Cord Injuries; Thoracic Vertebrae; Urethra; Vasoactive Intestinal Peptide

Specimens of urethra were obtained from patients with cervical and thoracic spinal cord lesion with detrusor-sphincter dyssynergia and from patients with lower motor neurone lesion with detrusor areflexia, undergoing transurethral sphincterotomy. Neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) in nerves associated with both the smooth and striated muscle components of the urethral sphincter were studied immunohistochemically and by immunoassay. In patients with detrusor-sphincter dyssynergia following cervical and thoracic spinal cord injury, NPY- and VIP-immunoreactive varicose nerve fibres were seen in both the smooth and striated muscle components of the urethral sphincter. In the smooth muscle, NPY- and VIP-immunoreactive nerves did not appear to have any particular orientation, but in the striated muscle region they were found to run along the length of individual muscle fibres. In patients with detrusor areflexia following lower motor neurone lesion, while the pattern, density and fluorescence intensity of NPY- and VIP-immunoreactive nerves in the smooth muscle of the sphincter mechanism appeared the same as seen in patients with detrusor-sphincter dyssynergia, there was a marked increase in the density of these nerves in the striated muscle region of the sphincter mechanism. Quantitation of the peptides by immunoassay was consistent with the histochemical findings, with significantly higher levels of both NPY and VIP in the striated muscle of patients with lower motor neurone lesion, compared to those with cervical and thoracic spinal cord lesion, p = 0.04. NPY and VIP levels in urethral smooth muscle were in the same range in lower motor neurone lesion patients and cervical and thoracic spinal cord lesion patients. We conclude that there are increased NPY- and VIP-containing fibres in striated muscle of the intrinsic external urethral sphincter in patients with areflexic bladder compared with those with detrusor-sphincter dyssynergia.

Topics: Adult; Enzyme-Linked Immunosorbent Assay; Humans; Male; Muscles; Neurons; Neuropeptide Y; Radioimmunoassay; Spinal Cord Injuries; Urethra; Urinary Bladder, Neurogenic; Vasoactive Intestinal Peptide

Specimens obtained by transurethral sphincterectomy from patients with spinal cord injury and carcinoma of the bladder were studied immunohistochemically. In the smooth muscle region of the sphincter, vasoactive intestinal polypeptide-, substance P- and somatostatin-immunoreactive fluorescent, varicose nerve fibers were seen. In the striated muscle region, VIP-immunoreactive nerves were found around striated muscle fibers and bundles, while somatostatin- and substance P-immunoreactive nerves were confined to nerve bundles. In both the smooth and striated muscle regions of the intrinsic external urethral sphincter, VIP-immunoreactive nerves were seen around blood vessels. No differences were observed in the immunohistochemical localization of these peptide-containing nerves in the two groups of patients. No immunofluorescence for [Met]enkephalin, bombesin, neurotensin or serotonin was found in any nerves in the urethra.

Topics: Adolescent; Adult; Aged; Fluorescent Antibody Technique; Humans; Muscle, Smooth; Muscles; Nerve Fibers; Somatostatin; Spinal Cord Injuries; Substance P; Urethra; Urinary Bladder Neoplasms; Urinary Bladder, Neurogenic; Vasoactive Intestinal Peptide

Transplants of central nervous system to adult spinal cords are considered as potential aids in regeneration of the spinal cord and/or recovery of function after injury. The organization and development of the implant are important issues in seeking the potential for a transplant and host to become functionally integrated. This study uses embryonic cerebral cortex transplanted into the spinal cord of adult rats (T6) and examined the development and organization of the transplant with an antibody to vasoactive intestinal polypeptide (VIP). The cell bodies of VIP neurons are in the implants at 30 days postimplantation, but few of the somata have processes. By 45 days postimplantation, VIP neurons in the implant have dendrites and axons and are clearly recognizable as cortical bipolar cells which are not normally present in the thoracic spinal cord. These data show that neurons in embryonic cerebral cortical implants into the spinal cord elaborate the appropriate biochemical and morphological constituents in spite of the ectopic location. However, the cell processes develop at a slower than normal pace. Morphological interaction between the host spinal cord and the implant can be demonstrated possibly as early as 45 days postimplantation and clearly at 6 months following the implant. Thus, further examination of cerebral cortical implants as a potential aid in alleviation of paraplegia subsequent to spinal cord injury is warranted.

Topics: Animals; Cerebral Cortex; Immunoenzyme Techniques; Rats; Rats, Inbred Strains; Spinal Cord Injuries; Vasoactive Intestinal Peptide