Jiuan Miaw Liao

Colon mustard oil instillation induced cross-organ reflex sensitization on the pelvic-urethra reflex activity in rats.

ABSTRACT We investigated the participation of cyclin‐dependent kinase‐5 (Cdk5)‐mediated N‐methyl‐d‐aspartate receptor (NMDAR) NR2B subunit phosphorylation in cross‐organ reflex sensitization caused by colon irritation. The external urethral sphincter electromyogram (EUSE) reflex activity evoked by the pelvic afferent nerve test stimulation (TS, 1 stimulation/30 s) and protein expression in the spinal cord and dorsal root ganglion tissue (T13‐L2 and L6‐S2 ipsilateral to the stimulation) in response to colon mustard oil (MO) instillation were tested in anesthetized rats. When compared with a baseline reflex activity with a single action potential evoked by the TS before the administration of test agents, MO instillation into the descending colon sensitized the evoked activity characterized by elongated firing in the reflex activity in association with increased protein levels of Cdk5, PSD95, and phosphorylated NR2B (pNR2B) but not of total NR2B (tNR2B) in the spinal cord tissue. Both cross‐organ reflex sensitization and increments in protein expression were reversed by intra‐colonic pretreatments with ruthenium red (a non‐selective transient receptor potential vanilloid, TRPV, antagonist), capsaizepine (a TRPV1‐selective antagonist), lidocaine (a nerve conduction blocker) as well as by the intra‐thecal pretreatment with APV (a NRMDR antagonist) Co‐101244 (a NR2B‐selective antagonist) and roscovitine (a Cdk5 antagonist). Moreover, compared with the control group, both the increase in pNR2B and the cross‐organ reflex sensitization were attenuated in the si‐RNA of NR2B rats. All these results suggested that Cdk‐dependent NMDAR NR2B subunit phosphorylation mediates the development of cross‐organ pelvic–urethra reflex sensitization caused by acute colon irritation which could possibly underlie the high concurrence of pelvic pain syndrome with irritable bowel syndrome.

Estrous cycle variation of TRPV1-mediated cross-organ sensitization between uterus and NMDA-dependent pelvic-urethra reflex activity

Cross-organ sensitization between the uterus and the lower urinary tract (LUT) underlies the high concurrence of pelvic pain syndrome and LUT dysfunctions, and yet the role of gonadal steroids is still unknown. We tested the hypothesis that cross-organ sensitization on pelvic-urethra reflex activity caused by uterine capsaicin instillation is estrous cycle dependent. When compared with the baseline reflex activity (1.00 +/- 0.00 spikes/stimulation), uterine capsaicin instillation significantly increased reflex activity (45.42 +/- 9.13 spikes/stimulation, P < 0.01, n = 7) that was corroborated by an increase in phosphorylated NMDA NR2B (P < 0.05, n = 4) but not NR2A subunit (P > 0.05, n = 4) expression. Both intrauterine pretreatment with capsazepine (5.02 +/- 2.11 spikes/stimulation, P < 0.01, n = 7) and an intrathecal injection of AP5 (3.21 +/- 0.83 spikes/stimulation, P < 0.01, n = 7) abolished the capsaicin-induced cross-organ sensitization and the increment in the phosphorylated NR2B level (P < 0.05, n = 4). The degrees of the cross-organ sensitization increased in a dose-dependent manner with the concentration of instilled capsaicin from 100 to 300 microM in both the proestrus and metestrus stages, whereas they weakened when the concentrations were higher than 1,000 microM. Moreover, the cross-organ sensitization caused by the uterine capsaicin instillation increased significantly in the rats during the proestrus stage when compared with the metestrus stage (P < 0.01, n = 7). These results suggest that estrogen levels might modulate the cross-organ sensitization between the uterus and the urethra and underlie the high concurrence of pelvic pain syndrome and LUT dysfunctions.

Effects of a calcineurin inhibitor, tacrolimus, on glutamate-dependent potentiation in pelvic-urethral reflex in anesthetized rats

Effects of tacrolimus, a protein phosphatase 2B inhibitor, on the reflex plasticity between the pelvic afferent nerve fibers and the urethra were examined in urethane-anesthetized rats. Repetitive stimulation (1 Hz) induced a potentiation (0.9+/-0.2 and 10.5+/-1.6 spikes in control and repetitive stimulation groups, respectively, P<0.01, N=10) in the activities of the pelvic-urethral reflex. Intrathecal tacrolimus (0.1 mM, 10 microl, bolus) blocked repetitive stimulation-induced potentiation in pelvic-urethral reflex activities (3.2+/-0.9 spikes in tacrolimus group versus 10.5+/-1.6 spikes in repetitive stimulation group, P<0.01, N=10). Glutamate (intrathecal, 0.1 mM, 10 microl, bolus) and N-methyl-D-aspartic acid (intrathecal, 0.1 mM, 10 microl, bolus) both reversed the blocking effects exerted by tacrolimus on repetitive stimulation-induced pelvic-urethral reflex potentiation (15.0+/-1.4 spikes in glutamate group and 11.4+/-1.4 spikes in N-methyl-D-aspartic acid group versus 3.2+/-0.9 spikes in tacrolimus-treated repetitive stimulation group, P<0.01, N=7). In addition, the reversal effect elicited by these two agonists of glutamate receptors showed no statistical difference (P=NS, N=7). All these results demonstrated that tacrolimus could block glutamatergic N-methyl-D-aspartic acid receptor-mediated potentiation in pelvic-urethral reflex activities. This finding may be pathologically relevant in patients who take tacrolimus as immunosuppressant therapy. Whether tacrolimus will induce urine incontinence in such patients or not needs further investigation.

Electroacupuncture at Hoku elicits dual effect on autonomic nervous system in anesthetized rats

To address the effect of electroacupuncture (Ea) on the autonomic nerve activity, responses of arteriole blood pressure (BP), intragastric pressure (IGP) and parasympathetic vagal nerve activity (VNA) to Ea were investigated in alpha-chloralose anesthetized rats. The acupoint: Hoku (Li-4) was tested with two different stimulation frequencies (2 and 20 Hz). Decrease in VNA and basal IGP associated with elevation of BP were elicited during Ea at Hoku with stimulation intensity of 20 times of motor threshold. The pattern of response induced by the low frequency Ea (LFEa) was different from that by the high frequency Ea (HFEa), i.e. a tonic effect was elicited by the LFEa, while a phasic one was induced by the HFEa. All the results in this study implicated that: (1) Ea at Hoku may activate the sympathetic and simultaneously inhibit the gastric parasympathetic nerve; (2) Ea at Hoku with different stimulation frequencies may elicit distinct mechanism to induce therapeutic effect; (3) Ea at Hoku may ameliorate the hyperactive stomach in clinical therapy.

Depressor effect on blood pressure and flow elicited by electroacupuncture in normal subjects

To clarify the effect of electroacupuncture (Ea) on the activity of the cardiovascular system in normal individuals, hemodynamic parameters including arterial blood pressure (BP), finger blood flow (FBF) and heart rate (HR) as well as paravertebral temperature (PVT) were non-invasively recorded under Ea stimulation. Surface stimulation electrode was placed on the Hoku point (Li-4). Square wave pulses (0.05 ms) were applied from a stimulator with a stimulation frequency of 2 Hz (3 min). The stimulation intensity was five times of sensory threshold. BP and FBF were decreased (68.5+/-6.0%, P<0.01 and 96.8+/-1.1%, P<0.01 of control, respectively, n=7) while HR and PVT were increased significantly (115.0+/-5.1 of control, P<0.05 and 0.054+/-0.004 degree C, P<0.01, respectively, n=7) during Ea treatment. The results suggested an inhibition in sympathetic outflow, which induced vasodilatation of systemic arteriole and decrease in BP and FBF were elicited by Ea stimulation.

Impairment of cerebral hemodynamic response to the cold pressor test in patients with Parkinson's disease.

BACKGROUND AND PURPOSE Disturbance of the autonomic nervous system (ANS) is frequently encountered in Parkinsons disease (PD). In this study, we examined changes in systemic and cerebral hemodynamics during the cold pressor test (CPT) to determine whether cerebrovascular reactivity, controlled by the sympathetic nervous system, is intact or impaired in patients with PD. METHODS Forty-nine patients with PD and 49 sex- and age-matched non-PD subjects were evaluated. Measurements were performed in the resting state and over a period of 1min of CPT. The cerebral blood flow velocity (CBFV) and pulsatility index (PI) of the middle cerebral artery (MCA) were recorded by transcranial color-coded Doppler ultrasonography (TCCS). Mean arterial blood pressure (MAP), heart rate (HR), and end-tidal CO(2) (Et-CO(2)) were investigated simultaneously. The resistance of the cerebrovascular bed (CVR) was calculated as the ratio of mean arterial blood pressure to mean cerebral blood flow velocity (Vm). Changes of Vm, PI and CVR in response to the cold pressor test were evaluated. RESULTS Baseline values for control and PD subjects showed no statistical difference. CPT induced a significant increase in MAP, HR, and Vm in both groups. Pulsatility index (PI) and CVR were decreased in both groups during CPT. Percent increases of Vm (P<0.001) and MAP (P=0.011) were significantly higher while the percent decreases of PI (P=0.002) and CVR (P=0.007) were significantly decreased more in the non-PD group. CONCLUSIONS This study indirectly shows that ANS-mediated cerebrovascular reactivity is impaired in patients with PD. Further investigations are needed to confirm the hypothesis that using the cold pressor test to evaluate cerebrovascular reactivity might be beneficial in early diagnosis of impairment of ANS-mediated cerebrovascular autoregulation in patients with PD.

Pressor effect on blood pressure and renal nerve activity elicited by electroacupuncture in intact and acute hemorrhage rats

The neural mechanism underlying the effect of electroacupuncture (Ea) on arterial blood pressure (BP) and renal nerve activity (RNA) in the intact state and during acute hemorrhage was investigated in anesthetized rats. Two acupoints, Hoku (Li-4, at the junction of the first and the second metacarpal bone) and Tsusanli (St-36, at the lateral upper tibia bone), were tested using Ea of two different frequencies (2 and 20 Hz). In the intact state, Ea at Hoku elicited an elevation of BP in parallel with RNA, while Ea found no response with identical parameters at Tsusanli. The pattern of the pressor response caused by a low frequency Ea (2 Hz) at Hoku was different than a high frequency one (20 Hz), i.e. a tonic effect was elicited with 2 Hz, while a phasic one was induced with 20 Hz. In mild hemorrhage conditions (10% of BP decrease), similar pressor effects, as in intact rats, were also elicited by Ea. However, in severe hemorrhage conditions (20 and 30% BP decrease), Ea induced a pressor effect on RNA and an attenuated effect on BP. BP and RNA showed a significant correlation in intact and mild hemorrhage conditions, but not in severe hemorrhage conditions. All the results suggested that Ea at Hoku with appropriate stimulation parameters can increase and maintain BP in normal and hemorrhage conditions, and such a therapeutic technique has potential in clinical practice.

Nicotine-activated descending facilitation on spinal NMDA-dependent reflex potentiation from pontine tegmentum in rats

This study was conducted to investigate the possible neurotransmitter that activates the descending pathways coming from the dorsolateral pontine tegmentum (DPT) to modulate spinal pelvic-urethra reflex potentiation. External urethra sphincter electromyogram (EUSE) activity in response to test stimulation (TS, 1/30 Hz) and repetitive stimulation (RS, 1 Hz) on the pelvic afferent nerve of 63 anesthetized rats were recorded with or without microinjection of nicotinic cholinergic receptor (nAChR) agonists, ACh and nicotine, to the DPT. TS evoked a baseline reflex activity with a single action potential (1.00 +/- 0.00 spikes/stimulation, n = 40), whereas RS produced a long-lasting reflex potentiation (16.14 +/- 0.96 spikes/stimulation, n = 40) that was abolished by d-2-amino-5-phosphonovaleric acid (1.60 +/- 0.89 spikes/stimulation, n = 40) and was attenuated by 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline (7.10 +/- 0.84 spikes/stimulation, n = 40). ACh and nicotine microinjections to DPT both produced facilitation on the RS-induced reflex potentiation (23.57 +/- 2.23 and 28.29 +/- 2.36 spikes/stimulation, P < 0.01, n = 10 and 20, respectively). Pretreatment of selective nicotinic receptor antagonist, chlorisondamine, reversed the facilitation on RS-induced reflex potentiation caused by nicotine (19.41 +/- 1.21 spikes/stimulation, P < 0.01, n = 10) Intrathecal WAY-100635 and spinal transection at the T(1) level both abolished the facilitation on reflex potentiation resulting from the DPT nicotine injection (12.86 +/- 3.13 and 15.57 +/- 1.72 spikes/stimulation, P < 0.01, n = 10 each). Our findings suggest that activation of nAChR at DPT may modulate N-methyl-d-aspartic acid-dependent reflex potentiation via descending serotonergic neurotransmission. This descending modulation may have physiological/pathological relevance in the neural controls of urethral closure.

Impaired micturition reflex caused by acute selective dorsal or ventral root(s) rhizotomy in anesthetized rats

PURPOSE To clarify the contributions of parasympathetic inputs and outputs to the micturition reflex. MATERIALS AND METHODS Intra-vesical pressure (IVP), external urethral sphincter electromyogram (EMG), pelvic afferent nerve activities (PANA), and pelvic efferent nerve activities (PENA) as well as the time-derived IVP (dIVP, an index of bladder contractility) were evaluated in intact and acute dorsal or ventral root(s) rhizotomized (DRX and VRX, respectively) rats. RESULTS In DRX rats, when compared with that in intact stage, the voiding frequency was decreased (75 +/- 15% of intact, P < 0.05, n = 8), while the threshold pressure to trigger voiding contractions was significantly increased (187 +/- 75% of intact, P < 0.05, n = 8). In addition, several insufficient contractions (5.3 +/- 3.5 contractions/voiding, P < 0.05, n = 8) occurred in ahead of each voiding contraction. On the other hand, in VRX rats, the peak and rebound IVP were significantly decreased (90 +/- 3.5% and 75 +/- 11.3% of intact, P < 0.01, n = 8), while the threshold pressure was not affected (102 +/- 11% of intact, P = NS, n = 8). The time-derived parameters were significantly decreased in VRX (peak dIVP, 78 +/- 10.2%, rebound dIVP, 75 +/- 15.6%, minimal dIVP, 68 +/- 14% of intact, P < 0.01, n = 8) but only peak dIVP was decreased (85 +/- 11% of intact, P < 0.01, n = 8) in DRX rats. CONCLUSION Acute selective DRX and VRX rat can be an animal model to investigate peripheral neural control in micturition functions.

Effects of bilateral T2-sympathectomy on static and dynamic heart rate responses to exercise in hyperhidrosis patients

The static/dynamic changes of gas exchange, heart rate (HR) and blood pressure in terms of work rate (WR) and WR changes in ramp exercise were investigated by cardio-pulmonary exercise tests (CPETs) in hyperhidrosis patients before (W0), one week (W1) and four weeks (W4) after bilateral T2-sympathectomy. Accompanied by constant oxygen consumption and WR at peak exercise and similar oxygen debt in recovery, the HR significantly (p<0.05) decreased statically in all stages of CPET, but was not altered dynamically, i.e., similar slope but significantly diminished intercept in HR changes versus WR changes (70+/-6.0 vs. 82+/-19 beats/min, p<0.01), in W1 (n=11), compared to W0 (n=13). However, this surgical effect on static HR changes seemed to have disappeared in W4 (n=8), albeit at that time the static blood pressure decreased significantly during exercise. These findings suggest that bilateral T2-sympathectomy will reduce static HR without causing cardiovascular insufficiency in one week, and would then recover by one month in hyperhidrosis patients.