OBJECTIVETo identify the effects of NMDA receptor subunits NR2A and NR2B expression in rat's hippocampus after exposure to 1800 MHz radiofrequency radiation.

METHODSFour-week old female Wistar rats were randomly divided into four groups, with 12 animals for each. The subjects in two experimental groups had been continuously exposed to 1800 MHz microwave radiation (CW) with respective power density of 0.5 mW/cm(2) and 1.0 mW/cm(2) 12 hours each day for 21 days. Meanwhile, sham-controls were carried out. The brain tissue sections were performed by immunohistochemistry to demonstrate both expressions of NR2A, NR2B immune-activity in the hippocampal CA1, CA3 and DG by using computer-assisted image analysis system.

RESULTSIn NR2A: the expression of 0.5 mW/cm(2) power density group was significantly lower than 0 mW/cm(2) power density group in CA3 [(8.5 +/- 1.5) vs (11.1 +/- 1.8), P < 0.01] and had not been significantly changed in CA1 and DG. The expression of 1.0 mW/cm(2) power density group was significantly lower than 0 mW/cm(2) power density group in CA1 and CA3 [(7.9 +/- 1.6) vs (9.7 +/- 1.5); (8.4 +/- 1.7) vs (11.1 +/- 1.8), respective P < 0.05, P < 0.01] and had not been significantly changed in DG. In NR2B: the expression of 0.5 mW/cm(2) power density group was significantly lower than 0 mW/cm(2) power density group in CA1 and CA3 [(16.4 +/- 1.0) vs (17.8 +/- 1.6); (9.6 +/- 1.9) vs (11.2 +/- 2.1), respective P < 0.05]. The expression of 1.0 mW/cm(2) power density group was significantly lower than 0 mW/cm(2) power density group in CA1, CA3 and DG [(13.1 +/- 2.4) vs (17.8 +/- 1.6); (9.3 +/- 1.4) vs (11.2 +/- 2.1); (7.3 +/- 0.1) vs (8.5 +/- 1.0), respective P < 0.01, P < 0.05, P < 0.05].

CONCLUSIONThere were findings of the effects on NMDA receptor subunits in different hippocampus sections after exposure to 1800 MHz radiofrequency radiation.

Animals ; Female ; Hippocampus ; metabolism ; radiation effects ; Immunohistochemistry ; Radio Waves ; Rats ; Rats, Wistar ; Receptors, N-Methyl-D-Aspartate ; biosynthesis

OBJECTIVE: To determine the regulation of the expression of NMDA receptor-1 induced by NMDA in the brain of neonatal SD rats. METHODS: Neonatal SD rats (n=90) were randomly divided into normal control (n=6) and NMDA injected group (subdivided into 10 nmol-0 min, 15 min, 30 min, 1 h, 2 h, 4 h groups, and 10, 20, 50 nmol groups, each n=6). NMDA fluorescent inmmunohistological staining and TTC (2,3,5-triphenyltetrazoliun chloride) staining techniques were used. RESULTS: At 30 min after the injection of 10 nmol NMDA, a few NR1 positive cells could be observed along the injection tract. At 1 h after the injection, NR1 positive cells in large quantity could be observed in the hippocampal CA1 region and paraventricular thalamus of the ipsilateral hemisphere. The number and location of positive cells at 2 h and 4 h after the injection were not much different from that at 1 h after the injection. At 2 h after injection, stronger NR1 expression was observed in the 50 nmol injection group. In addition, slight crinkle of the cell wall with mild condensation of the nuclei was also observed in the 50 nmol injection group. At 2 h after the injection, no abnormality was observed in 10, 20, or 50 nmol group after TTC staining. CONCLUSION The NR1 induced by NMDA is expressed in a time-dependent and dose-dependent pattern after a short period of "delay", providing a possible "therapeutic window" for using NMDA receptor antagonist to treat diseases relating to the NMDA receptor activation.
Animals ; Animals, Newborn ; Brain ; metabolism ; Dose-Response Relationship, Drug ; Mice ; N-Methylaspartate ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; Time Factors

OBJECTIVETo observe the change of the gene expression of N-methyl-D-aspartate receptors (NMDAR) subunits in rat hippocampus after scalding.

METHODSThe backs of the rats were shaved and immersed in warm water for 10 sec. to make control group (C), and the backs shaved and immersed in hot water (90 degrees C) for 10 sec to make 30% full skin scalding model as the scalding group (S). The mRNA expression of the subunits of rat hippocampus NMDAR-NMDAR1, NMDAR2A, NMDAR2B, NMDAR2D was determined with RT-PCR technique in C group and at 0.5, 1, 2 and 4 postburn hours (PBHs) in S group.

RESULTS(1) There exhibited no obvious change of the mRNA expression of all the subunits of NMDAR at 0.5 and 1 PBH in S group when compared with that in C group. But the mRNA expression of NMDAR1 increased for 24.3% and 20.9% and that of NMDAR2A increased for 27.8% and 27.6% at 2 and 4 PBHs respectively when compared with that in C group (P < 0.05). In addition, the mRNA expression of NMDAR2B and NMDAR2D revealed no change after scalding.

CONCLUSIONThe receptor channel constructed by NMDAR1/NMDAR2A demonstrated increased mRNA expression at 2 PBH, which might lead to the further opening of NMDAR after scalding which might participate in the maladjustment of HPA axis during scalding stress and the following pathophysiological changes.

Animals ; Burns ; metabolism ; pathology ; Disease Models, Animal ; Female ; Gene Expression ; Hippocampus ; metabolism ; pathology ; Male ; Rats ; Rats, Wistar ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; genetics

OBJECTIVE: To investigate the effects of N-methyl-D-aspartate receptor (NMDAR) in the spinal dorsal horn in visceral hypersensitivity in rats with colonic inflammation. METHODS: Seventy adult male Sprague-Dawley (SD) rats were randomly divided into the experimental group and the control group. Colonic inflammation was induced in the experimental rats by intraluminal administration of trinitrobenzenesulfonic acid (TNBS). Saline was administered intraluminally in the control rats. After 3, 7, 14, and 28 days of administration, abdominal contractions induced by inflation of a balloon colonically inserted were recorded in rats by implanting electrodes in the abdominal striated muscles. Immunohistochemistry method was used to study the expression of NMDAR1 and NMDAR2A/B in lumbarsacral spinal cord after inflammation. RESULTS: Colonic distension evoked a significant increase of abdominal contractions after 3, 7 and 14 days of TNBS administration. After 28 days of TNBS administration, abdominal contractions were still significantly increased in 2 TNBS-treated rats compared with the control rats. After 7 and 14 days of TNBS administration, NMDAR1 and NMDAR2A/B-immunoreactive cells were significantly increased compared with the control group (P <0.05). Twenty-eight days after TNBS administration, the number of NMDAR1-IR and NMDAR2A/B-IR neurons was still significantly increased in 4 TNBS-treated rats compared with the saline-treated rats (P < 0.05). CONCLUSION NMDAR was involved in the transmission of visceral nociceptive stimuli. After the remission of colonic inflammation, increased expression of NMDAR1 and NMDAR2A/B in the spinal dorsal horn may induce persistent neuronal hyperactivity, which results in visceral hypersensitivity.
Animals ; Colitis ; chemically induced ; metabolism ; Male ; Posterior Horn Cells ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; genetics ; Trinitrobenzenesulfonic Acid

To study the antiepileptic mechanism of vagus nerve stimulation (VNS), we used the methods of in situ hybridyzation and image analysis to detect the expression of NMDAR1 mRNA and GABAA receptor alpha 1 subunit mRNA (GABAAR alpha 1 mRNA) in the thalamic reticular nuclus. The results show that the NMDAR1 mRNA expression of rats administered pentylenetetrazole(PTZ) is higher than that of control group. By treating with VNS, it decreased. On the contrary, the expression of GABAAR alpha 1 mRNA in the thalamic reticular nuclus of PTZ group rats is lower than that of control group. For rats treated with VNS, it increased. Therefore, it is concluded that VNS may reduce the excitability of cerebral cortices by depressing the activities of glutamic acid receptors (GluR) and by promoting the activities of gamma-aminobutyric acid receptors(GABAR) in thalamic reticular nuclus. So the formation and development of seizures are inhibited.
Animals ; Electric Stimulation Therapy ; methods ; Epilepsy ; chemically induced ; therapy ; Intralaminar Thalamic Nuclei ; metabolism ; Male ; Pentylenetetrazole ; toxicity ; RNA, Messenger ; biosynthesis ; Rats ; Rats, Wistar ; Receptors, GABA-A ; biosynthesis ; genetics ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; genetics ; Vagus Nerve ; physiopathology

To observe the effect of multiple electroacupuncture (EA) on the pain threshold and the regulation of N-methyl-D-aspartate (NMDA) receptor in dorsal root ganglia (DRG) of neuropathic pain rats. Rats were prepared with a unilateral chronic constriction injury (CCI) to the sciatic nerve. EA was done in acupoints "Huan Tiao" and "Yang Ling Quan" for 30 min every day and the thermal thresholds were detected after EA at 3, 5, 7, 10, 14 days after operation. On day 14 after nerve injury, the in situ hybridization method was used to investigate the change of NMDA R1 mRNA in L4-L5 DRG. The thermal threshold reduced significantly from day 3 after operation in CCI rats. After multiple EA treatment, the ipsilateral thermal hyperalgesia relieved gradually and the thermal threshold had no difference with control side after day 5 (P > 0.05). From Day 7 after operation, the thermal threshold at each time point were significantly different compared with CCI group respectively (P > 0.05). Moreover the EA had accumulative effect. On Day 14 after operation, the NMDAR1 mRNA positive neurons and the mean optic density in ipsilateral L4-5 DRG were less than that of control side (P < 0.05), mainly in medium and small neurons. After EA treatment, the NMDAR1 mRNA positive neurons in ipsilateral DRG had no considerable difference comparing with those of control side, significantly increased comparing with CCI group (P < 0.05). It's concluded that the NMDA receptors in DRG relate closely with the generation and development of neuropathic pain. The multiple EA treatment can attenuate the thermal hyperlagesia of neuropathic pain rats and regulate the NMDA receptor.
Animals ; Electroacupuncture ; Ganglia, Spinal ; metabolism ; Hyperalgesia ; physiopathology ; Male ; Neuralgia ; metabolism ; physiopathology ; Pain Measurement ; Pain Threshold ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; genetics ; Sciatic Nerve

To investigate the effect of N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 on the formalin-induced cyclooxygenase-2 (COX-2) expression in the dorsal horn of the rat spinal cord. Forty-eight male Sprague-Dawley rats were divided into 4 groups: control, formalin, formalin+normal saline (NS) and formalin+MK-801 groups. Rats in formalin, formalin+NS and formalin+MK-801 groups were subcutaneously injected with 0.2 ml 5% formalin into the plantar surface of the right hind paw. NS or MK-801 solution (10 microl) was intrathecally injected under transient ether anesthesia 15 min prior to the formalin injection in the formalin+NS and formalin+MK-801 groups, respectively. Flinch reflex was measured within 1 h after the formalin injection and expression of COX-2 in the dorsal horn of the L(5) segment of the spinal cord was assayed 24 h after the formalin injection using immunohistochemistry. Formalin evoked a biphasic flinch reflex. MK-801 produced a limited effect on the flinch reflex of phase 1, but produced significant and dose-dependent suppression on the flinch reflex of phase 2. The number and immunostaining density, shown by grey degree which was inversely proportional to the immunostaining density, of immunoreactive soma in the superficial (mainly I-II) and deep (IV-VI) laminae of the L(5) spinal cord in formalin and formalin+NS groups increased significantly, in contrast to those in the control group (p<0.01). The number and immunostaining density of immunoreactive soma decreased significantly in formalin+MK-801 group, in comparison with the formalin+NS group (p<0.05). The degree of the decrease was proportional to the dosage of MK-801 used. In addition, there were some immunoreactive processes especially in the superficial laminae, which extended as a continuous band across the dorsal horn after the formalin injection. Change in immunostaining density of the processes after administration of MK-801 was similar to that in the immunoreactive soma. The results showed that intrathecal injection of MK-801 significantly inhibited the increase of COX-2 expression in the spinal dorsal horn induced by the formalin injection in a dose-dependent manner, suggesting that the activation of NMDA receptor is one of the mechanisms for the formalin-induced increase of COX-2 expression in the spinal dorsal horn.
Animals ; Cyclooxygenase 2 ; Dizocilpine Maleate ; pharmacology ; Formaldehyde ; Isoenzymes ; biosynthesis ; genetics ; Posterior Horn Cells ; enzymology ; Prostaglandin-Endoperoxide Synthases ; biosynthesis ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; Spinal Cord ; enzymology

The effect of zinc on the damage of primary cultured hippocampal neurons induced by corticosterone (CORT) was studied. Neuronal injury and expression of NMDA receptor subunits (NR1,NR2A,NR2B) mRNA were detected by using in situ staining and RT-PCR, respectively. Neurons treated with 5 micromol/L CORT for 24 h showed decreased survival rates and increased apoptotic rates compared with the controls; co-application of CORT and 10 or 100 micromol/L Zn(2+) attenuated apoptotic rates while 250 micromol/L Zn(2+) worsened CORT-induced neuronal injury. Expression of NR1, NR2B mRNA in neurons treated by 5 micromol/L CORT for 24 h was significantly increased, while those concurrently added with 10 or 100 micromol/L Zn(2+) showed no changes. No statistic difference in NR2A mRNA was obtained under any treatment. These results suggest that zinc can bilaterally regulate neuronal injuries induced by CORT, among while NMDA receptors probably play an important role.
Animals ; Animals, Newborn ; Apoptosis ; drug effects ; Cells, Cultured ; Corticosterone ; pharmacology ; Hippocampus ; pathology ; Neurons ; pathology ; Neuroprotective Agents ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; classification ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Zinc ; pharmacology

Neuronal migration disorders (NMDs) constitute the main pathologic substrate of medically intractable epilepsy in human. This study is designed to investigate the changes in expression of glutamate receptor subtypes on radiation-induced NMD in rats. The lesion was produced by intrauterine irradiation (240 cGy) on E17 rats, and then 10 weeks old rats were used for the study. The pathologic and immunohistochemical findings for glutamate receptor subunit proteins on NMD cortex were correlated with development of behavioral seizures and EEG abnormality. Spontaneous seizures uncommonly occurred in NMD rats (5%); however, clinical stages of seizures were significantly increased in NMD rats by an administration of kainic acid. Brains taken from irradiated rats revealed gross and histopathologic features of NMD. Focal cortical dysplasia was identified by histopathology and immunohistochemistry with neurofilament protein (NF-M/H). Significantly strong NR1 and NR2A/B immunoreactivities were demonstrated in cytomegalic and heterotopic neurons of NMD rats. The results of the present study indicate that epileptogenesis of NMD might be caused by upregulation of glutamate receptor expression in dysplastic neurons of the rat cerebral cortex with NMDs.
Animals ; Cell Movement ; Cerebral Cortex/*metabolism ; Electroencephalography ; Glutamic Acid/metabolism ; Immunohistochemistry ; Kainic Acid/pharmacology ; Neurons/*metabolism/pathology ; Rats ; Rats, Wistar ; Receptors, Glutamate/metabolism ; Receptors, N-Methyl-D-Aspartate/*biosynthesis ; Support, Non-U.S. Gov't ; Time Factors ; *Up-Regulation

The antisense approach and RT-PCR were used to study the effects of muscarinic receptors on the scores of morphine-withdrawal syndrome and the expression of NMDA receptor subtypes (NR(1A) and NR(2A)) mRNA in rat spinal cord and brainstem. The concentrations of glutamate in periaqueductal grey (PAG) of morphine-withdrawal rats were determined by capillary electrophoresis with laser-induced fluorescence detection. The data showed that the NR(1A) and NR(2A) mRNA levels were increased significantly in the spinal cord and brainstem 1 h after the injection of naloxone (4 mg/kg, i.p.) in morphine-dependent rats. Moreover, in morphine-dependent rats pretreated (i.p.) with scopolamine (0.5 mg/kg), or pirenzepine (10 mg/kg), MK801 (0.125 mg/kg), L-N-nitroarginine methylester (10 mg/kg) 30 min before naloxone injection, the NR(1A) and NR(2A) mRNA levels were significantly lower than those of 1 h morphine-withdrawal rats. Intrathecal injection of NR(1A) or M(2) receptor antisense oligonucleotides (A-oligo, 4 microg/per rat) 24 h prior to naloxone challenge could block the morphine withdrawal symptoms including wet dog shaking, irritability, salivation, diarrhea, chewing and weight loss. Meanwhile, in morphine-dependent rats the NR(1A) mRNA levels in the spinal cord and brainstem were down-regulated by intrathecal injection of M(2) receptor A-oligo. The glutamate concentrations in PAG microdialysis were increased to a maximal level 15 min after naloxone injection. The glutamate response was inhibited by pretreatment with M(2) receptor A-oligo but not by M(1) A-oligo. The results suggest that the expression of NMDA receptors and the release of glutamate in brainstem are involved in the processes of morphine withdrawal and that the NMDA receptor expression is possibly regulated by the muscarinic receptors during morphine withdrawal.
Animals ; Brain Stem ; metabolism ; Glutamic Acid ; metabolism ; Male ; Morphine ; adverse effects ; Periaqueductal Gray ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Muscarinic ; physiology ; Receptors, N-Methyl-D-Aspartate ; biosynthesis ; genetics ; Spinal Cord ; metabolism ; Substance Withdrawal Syndrome ; genetics ; metabolism