Neuroscience letters
-
Neuroscience letters · Sep 2011
Galanin modulating effect on restraint stress-induced short- and long-term behavioral changes in Wistar rats.
The neuropeptide galanin has been recognized as a possible neurotransmitter/neuromodulator, and in addition has been implicated in anxiety- and depression-related behaviors. The present study demonstrates increased locomotion and rearing after galanin (0.3mg/kg) that was given intraperitoneally (i.p.) to intact Wistar rats which were tested 1h later in the open field (OF). These effects, which suggest an anxiolytic-like action, were blocked by i.p. administered peptidic galanin antagonist M40. ⋯ Testing performed on the 12th day after the last stress and galanin treatment with 0.3mg/kg revealed an increased locomotion compared with unstressed and stress-exposed rats. Our results demonstrate that behavioral effects of the peptide galanin are evident even after i.p. administration. These results also suggest that galanin elicits stress-modulatory action, and support the notion that the galaninergic system may serve as a drug target in stress-related conditions.
-
Neuroscience letters · Sep 2011
Controlled Clinical TrialAbnormal spontaneous brain activity in medication-naïve ADHD children: a resting state fMRI study.
Abnormal baseline brain functional connectivity in attention-deficit/hyperactivity disorder (ADHD) has been revealed in a number of studies by using resting-state functional MRI (rfMRI). The aim of this study was to investigate the spontaneous frontal activities in medication-naïve ADHD boys using the rfMRI derived index, amplitude of low-frequency fluctuation (ALFF). In total 17 ADHD boys and 17 matched controls were recruited to undergo rfMRI scan on a 3.0T MRI system. ⋯ With a corrected threshold of p<0.05 determined by AlphaSim, we found that in comparison with controls, ADHD patients demonstrated higher ALFF values in the left superior frontal gyrus and sensorimotor cortex (SMC), and lower ALFF values in the bilateral anterior, middle cingulate and the right middle frontal gyrus (MFG). Significant correlations were found between patients' WSCT measures and the peak ALFF located in the right MFG (r=0.69, p=0.02), and the left SMC (r=0.65, p=0.03). Our results revealed abnormal frontal activities at resting state associated with underlying physiopathology of ADHD, and suggested the ALFF analysis to be a potential approach in further exploration of this disorder.
-
Neuroscience letters · Sep 2011
Up-regulation of spinal glutamate transporters contributes to anti-hypersensitive effects of valproate in rats after peripheral nerve injury.
Valproate produces analgesia in animals and humans, however, its mechanisms of action are yet unknown. The present study examined effects of repeated administration of valproate on behavioral hypersensitivity and expression of glutamate transporter-1 (GLT-1) and glutamate-aspartate transporter (GLAST) in the spinal dorsal horn in rats after L5-L6 spinal nerve ligation (SNL). ⋯ This analgesia from valproate was blocked by the selective GLT-1 blocker dihydrokainic acid (DHK). These data suggest that valproate restores down-regulated expression of glutamate transporters in the spinal cord to presumably reduce glutamate signaling and to reduce hypersensitivity after nerve injury, and that combination of valproate with riluzole produces enhanced analgesia which relies on the spinal glutamate transporters.
-
Although isoflurane, a non-water soluble agent, has been known to block Na+ currents, its spinal anesthetic effect was not exposed. The aim of this experiment was to evaluate the local anesthetic effect of isoflurane in spinal anesthesia. After intrathecal injection of isoflurane on rats, the spinal anesthetic effect in motor function, proprioception and nociception were evaluated. ⋯ Isoflurane acted like lidocaine and produced dose-related spinal blockades of motor function, proprioception and nociception. Although isoflurane [27.6 (25.4-30.0)] had less potency when compared with lidocaine [1.0 (0.9-1.1)] (P<0.001) in spinal anesthesia, it caused a much longer duration of spinal blockades than lidocaine at equianesthetic doses (P<0.001). Our results showed that when compared with lidocaine, isoflurane produced a less potency but much longer duration in spinal anesthesia.
-
Neuroscience letters · Aug 2011
RGS9-2 modulates nociceptive behaviour and opioid-mediated synaptic transmission in the spinal dorsal horn.
The regulator of G protein signaling 9-2 (RGS9-2) is a constituent of G protein-coupled receptor (GPCR) macromolecular complexes with a major role in regulation of GPCR activity in the central nervous system. Previous in situ hybridization and Western blot studies revealed that RGS9-2 is expressed in the superficial dorsal horn of the spinal cord. ⋯ This modulatory role of RGS9-2 on opiate-mediated responses was further supported by electrophysiological studies showing that hyperpolarization of neurons in lamina II of the spinal dorsal horn evoked by application of DAMGO ([d-Ala2, N-MePhe4, Gly-ol]-enkephalin, a mu opioid receptor agonist) was diminished in RGS9 knockout mice. The results indicate that RGS9-2 enhances the effect of morphine and may play a crucial role in opiate-mediated analgesic mechanisms at the level of the spinal cord.