To identify the role of spinal cyclooxygenase (COX)-1 in the development and maintenance of postoperative pain, we examined the changes of COX-1 protein expression in lumbar spinal cord by immunohistochemistry and Western blot technique in rat plantar incision model at different time points (pre-incision or 2 h, 4 h, 6 h,12 h, 1 d, 2 d, 3 d, 5 d and 7 d after incision). We also studied the anti-allodynic effects of the COX inhibitors by intrathecal administration of non-selective COX inhibitors (ketorolac), selective COX-1 (SC-560) or COX-2 inhibitor (NS-398) immediately or 2 h, 24 h after incision. The mechanical allodynia was evaluated by using paw withdrawal threshold (PWT) response to mechanical stimulation on pre-incision, 2 h, 1 d, 2 d, 3 d, 5 d and 7 d after incision or 30 min after drug treatment. The result showed that COX-1 immunoreactive cells mainly focused in the superficial laminae of lumbar spinal dorsal horn and expression of spinal COX-1 protein increased after incision, peaked at 4 h (P＜0.01) and lasted for 12 h. Postoperative treatment with both SC-560 and ketorolac significantly alleviating the mechanical allodynia induced by skin incision, but NS-398 had no such effect. This study demonstrates that spinal COX-1 involves in the development and maintenance of postoperative hypersensitivity and intrathecal COX-1 inhibitor has anti-allodynic effect on incision pain in the rat.

Whole-cell patch clamp technique was performed on acutely isolated rat dorsal root ganglion (DRG) neurons to investigate the modulatory effect of caffeine on γ-aminobutyric acid (GABA)-activated currents (IGABA). The results showed that the majority of the neurons examined (97.4%, 113/116) were sensitive to GABA. 1-1000 μmol/L GABA activated a concentration-dependent inward current which manifested obvious desensitization. After the neurons were treated with caffeine (0.01-100 μmol/L) prior to the application of GABA (100 μmol/L) for 30 s, GABA-activated membrane currents were obviously inhibited. Caffeine shifted the GABA dose-response curve downward and decreased the maximum response to 57% without changing Kd value. These results indicate that the inhibitory effect is non-competitive. Theophylline showed a similar and stronger inhibitory effect on IGABA. The pretreatment with caffeine (10 μmol/L) inhibited IGABA, which was potentized by diazepam (1 μmol/L). Intracellular application of H-8 almost completely abolished the inhibitory effect of caffeine on IGABA. The present results suggest that caffeine may be able to antagonize the effect of presynaptic inhibition of GABA in primary afferent.

Effects of urotensin II (UII) on paraventricular nucleus (PVN) neurons of hypothalamus from brain slices of rats were examined by using extracellular recording technique. The results are as follows: (1) In response to application of UII (0.3, 3.0, 30.0, 300.0 nmol/L, n=39) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 32/39 (82.05% ) neurons were significantly decreased in a dose-dependent manner; (2) Pretreatment with bicuculline (BIC, 100 μmol/L), a specific GABAA receptor antagonist, led to a marked increase in SDR of 5/7 ( 71.43% ) neurons in an epileptiform pattern. The increased discharges were not significantly changed after UII ( 30.0 nmol/L ) was applied into the perfusate for 2 min; (3) Pretreatment with picrotoxin ( PIC, 50 μmol/L ), a selective blocker of Cl- channel, led to an increase in the SDR of all 12/12 (100%) neurons. The increased discharges were not influenced by the applied UII (30.0 nmol/L) for 2 min in 11/12 (91.67%) neurons; (4) Application of nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 50 μmol/L ) into the perfusate could significantly augment the SDR of 11/12 ( 91.67% ) neurons , while UII ( 30.0 nmol/L ) applied into the perfusate for 2 min led the augmented SDR of all (12/12, 100%) neurons decrease. The results suggest that UII decreases the excitability of PVN neurons of hypothalamus by potentiating GABAA receptor-mediated Cl- current.

Previous experiments has shown that Ginsenoside Rb1 (GRb1), which is one of the most important active ingredients in ginseng (Panax ginseng C.A. Meyer), reduced infarct and neurologic deficit followed by the transient cerebral ischemia in rats. The mechanism of this neuroprotective function is unclear. In this study, we tested whether the neuroprotective effect of GRb1 is achieved through preventing the neuronal apoptosis and modulating expression of neuronal apoptosis inhibitory protein (NAIP). Focal cerebral ischemia was induced by the middle cerebral artery occlusion (MCAO) in Wistar rats. GRb1 (40 mg/kg, i.p.) was administered immediately after the onset of reperfusion. The rats with neurological deficits were randomly divided into 2 groups: the ischemia and the GRb1 group. Each group was again divided into subgroups according to the various reperfusion time (3 h, 12 h, 1, 2, 3, 5, 10 days, n=4 per time point). Apoptotic cells were analyzed using TUNEL. Immunohistochemical method was used to assess expression of NAIP. This results showed that the number of apoptotic cells elevated at 3 h of reperfusion, and peaked at 24 h, then declined, but the number of apoptotic cells at 10 d after ischemia was significantly more than those of control groups (P＜0.01). Compared with ischemia group, the apoptotic cells decreased at all subgroups of GRb1; however, the significant differences were only found from 12 h to 3 d of reperfusion. In normal and sham groups, NAIP weak immunostaining was diffusely present in the neurons of parenchyma. The number of NAIP-positive cells started to increase in ischemic regions at 3 h after ischemia, peaked at 12 h and declined up to 5 d of reperfusion. At 5 d after ischemia, the number of NAIP-positive cells was less than that of control group (P＜0.05). A few astrocytes strongly expressed NAIP in the ischemic area. In the GRb1 group, the number of NAIP-positive cells from 12 h to 10 d after ischemia was evidently higher than in the ischemia group. Thus, these results suggest that GRb1 has potential ability to prevent apoptosis, the mechanism of which is related to induce expression of NAIP.

To investigate the relationship of the rotation stimulation with motion sickness, the expression of Fos protein in the whole brain of the rat stimulated by complex double rotation on two axes was observed in the present study. The rats were randomly divided into four groups: normal contral group; double-axes rotation stimulation group; the bilateral labyrinthectomy group; group of two-axes rotation stimulation after the bilateral labyrinthectomy. Immunohistochemical staining method was used to detect the expression of Fos protein in different regions of whole brain of the rat. The present results showed that: (1) No Fos-like immunoreactivity was detected in the brain of the rats in control group and the bilateral labyrinthectomy group; (2) In the double-axes rotation stimulation group, the Fos-like immunoreactive neurons were observed in many regions of the brain and brainstem of the rats following complex double-axes rotation stimulation, and the Fos-immunoreactivities were expressed in the nucleus. These Fos-immunopositive neurons were intensively distributed in different subnuclei of the vestibular nucleus complex (including medial, superior and spinal nuclei), nucleus of the solitary tract, locus coeruleus, medial and lateral parabrachial nucleus of the brainstem, paraventricular nucleus of the diencephalons and the amygdala of the limbic system; (3) The expression of Fos protein can be scarcely detected around forementioned regions in brains of the rats following complex two-axes rotation stimulation after the bilateral labyrinthectomy. The present results suggest that the double-axes rotation stimulation can activate effectively the vestibular neurons and many neurons of other region of the brain and brainstem are further activated through direct or indirect connections with vestibular nuclei after complex double rotation stimulation. These activated neurons may be related to the complex mechanism of the motion sickness.

We examined the effects of intracerebroventricular ( i. c. v) administration of adrenomedullin (ADM) on catecholaminergic neurons and the expression of c-fos gene in rat brain nuclei involved in cardiovascular regulation using double immunohistochemical method for Fos and tyrosine hydroxylase (TH). The results showed that: ( 1 ) Following icy administration of ADM (3 nmol/kg) , double-labeled neurons for Fos and TH were significantly increased in the area postrema ( AP), the nucleus of the solitary tract ( NTS), the nucleus paragigantocelluaris laterialis (PGL) and the locus coeruleus (LC). (2) Pretreatment with calcitonin gene-related peptide receptor antagonis CGRP8-37 (30 nmol/kg) significantly reduced the action of ADM (3 nmol/kg) in the brain. The present study suggested that ADM might activate the neurons of the brain nuclei involved in cardiovascular regulation, and supported the hypothesis that the central action of ADM were induced by activating the catecholaminergic neurons of brainstem nuclei involved in cardiovascular regulation, CGRP receptor might mediate the effects of ADM.

To investigate the neurotoxic effect of human immunodeficiency virus (HIV) gp120 on cultured dorsal root ganglion (DRG)neurons in vitro, dissociated and organotypic mouse embryo's DRG cell culture models were established. Both dissociated and organotypic DRG cultures were treated with HIV gp120 in different concentration (250 pmol/L and 1 nmol/L, respectively, 2 times/7 days). For dissociated DRG cultural cells, microtubule-associated protein 2 (MAP2) immunofluorescent labeling was processed for observing the changes of neuronal cell body and neurites. The change of the ultrastructure in the organotypic cultured DRG was observed by electron microscopy.The difference of the number and length of neurites between the control group and HIV gp120 treated groups were significant (P＜0.001),whereas there was no significant difference in the diameter of neurons between them (P＞0.05). The ultrastructural changes included the decrease or loss of cristae in mitochondria and accumulation of many high densed particles between the microtubules and the neurofilaments by using both the concentrations of HIV gp120 treatment. The present results indicate that HIV gp120 had a directly neurotoxic effect on the cultured DRG neurons, especially more sensitive to mitochondria.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease. A cardinal histopathologic feature of HD is the progressive loss of striatal medium spiny neurons. As there is no effective treatment for this fatal disease so far, we explore the therapeutic potential of nortriptyline to identify drugs that might be effective treatments for HD. N548mu [ 1955-128] huntingtin stable ST14A cell line was cultured and incubated in the presence or absence of serial concentrations of nortriptyline. Then R6/2 transgenic HD mice were treated with nortriptyline from five to twenty-one weeks of age. Nortriptyline protected striatal cells expressing mutant huntingtin when shifted to a nonpermissive temperature. Nortriptyline delay the disease onset to 127 d in R6/2 mice as compared with 102 d in saline-treated controls, but nortriptyline did not significantly delay mortality. As a gross marker of lack of systemic toxicity, there was no significant difference in the weight of the treated and control R6/2 mice. The results demonstrate that clinically reasonable doses of one of the identified drugs, nortriptyline, delays disease onset in a mouse model of the disease more than any previously identified compound. The most desirable features of a drug for HD are minimal toxicity and the ability to extend symptom-free living. Nortriptyline appears to be one such good candidate.

The present study aims to investigate the survival, migration and differentiation of the neural stem cells (NSCs) transplanted into the hippocampus of adult rat damaged by kainic acid. Hippocampal CA1 pyramid neurons were degenerated by stereotaxical injection of kainic acid, one week later, NSCs labeled by Hoechst33342 were transplanted into the damaged hippocampus. The rats were sacrificed at 1,2,4 and 8 weeks, and the brains were examined by immunohistochemical analysis to observe the survival, migration and differentiation of the NSCs in the lesioned hippocampus. The results showed that transplanted neural stem cells migrate in the mode of chain in pyramid layer of hippocampus and most of them express the astrocytic marker of GFAP, others express the neuronal marker of MAP2. These results suggest that transplanted neural stem cells migrate in the mode of chain in pyramid layer of hippocampus. Most of them differentiate intoastrocytes, others differentiate into neurons.

It has been reported that the small type of neurons in the dorsal root ganglion (DRG) play an important role in pain regulation by a presynaptic mechanism via the metabotropic type-B γ-aminobutyric acid receptors ( GABABR ). In order to understand whether the 2populations of the small type of the neurons, peptidergic and nonpeptidergic, in DRG share the same role, immunoflourescent histochemical methods and confocal laser scanning microscope were employed to investigate the expression of the GABABR in the peptidergic and nonpeptidergic small DRG neurons. The results revealed that 92% of the peptidergic and 90% of nonpeptidergic small DRG neurons express GABABR in their perikarya and central processes, which distribute in the various laminae of the spinal dorsal horn. These results suggest both the peptidergic and nonpeptidergic populations of the small neurons in the DRG share similar role in pain modulation via presynaptic mechanisms but in given laminae of the spinal dorsal horn.