Autapses selectively form in specific cell types in many brain regions. Previous studies have also found putative autapses in principal spiny projection neurons (SPNs) in the striatum. However, it remains unclear whether these neurons indeed form physiologically functional autapses. We applied whole-cell recording in striatal slices and identified autaptic cells by the occurrence of prolonged asynchronous release (AR) of neurotransmitters after bursts of high-frequency action potentials (APs). Surprisingly, we found no autaptic AR in SPNs, even in the presence of Sr²⁺. However, robust autaptic AR was recorded in parvalbumin (PV)-expressing neurons. The autaptic responses were mediated by GABA_A receptors and their strength was dependent on AP frequency and number. Further computer simulations suggest that autapses regulate spiking activity in PV cells by providing self-inhibition and thus shape network oscillations. Together, our results indicate that PV neurons, but not SPNs, form functional autapses, which may play important roles in striatal functions.
Parvalbumins/metabolism* ; Corpus Striatum/metabolism* ; Interneurons/physiology* ; Neurons/metabolism* ; Neostriatum

To study the effects of estrogen on the contents of dopamine (DA) and its metabolites in the amygdala (Amy) and striatum (Str) of rats, high performance liquid chromatography (HPLC) was used to measure the contents of DA and its metabolites in untreated ovariectomized (OVX) rats and OVX rats treated with estrogen. The contents of DA and its metabolites in Amy but not Str were significantly higher when the OVX rats were treated with a high dose of estradiol benzoate (EB). The turnover rate of DA in Amy of the OVX rats was lower than that of normal and EB-treated OVX rats. The turnover rate of DA in Amy was about twice as high as in the Str, while the content of DA in Amy was only one-sixth of that in the Str. The results obtained imply that serum concentration of estrogen is one of the important factors which affect the DA metabolism and content in the Amy of female rats, while the Str is not influenced by estrogen.
Amygdala ; metabolism ; Animals ; Corpus Striatum ; metabolism ; Dopamine ; metabolism ; Estrogens ; blood ; physiology ; Female ; Rats ; Rats, Wistar

The self-made high sensitivity and selectivity micro-biosensor was applied to monitor the change of dopamine in cerebral nucleus in rats in vivo. The micro-biosensor was prepared and used to detect dopamine level in vitro and monitor the dynamic change of dopamine in different cerebral nucleus in vivo. The results showed the lowest concentration of dopamine that could be detected by the biosensor was 32.5 nmol/L. Its positive peak was significantly different from that of AA, 5-HTP and E. The biosensor could keep working for monitoring the dopamine concentration in the cerebral tissue for more than 10 h. It was concluded that the microsensor has high sensitivity and selectivity to dopamine and can be used to dynamically monitor the change of dopamine in vivo.
Biosensing Techniques/*instrumentation ; Biosensing Techniques/methods ; Brain Chemistry ; Corpus Striatum/*metabolism ; Dopamine/*analysis ; Microelectrodes ; Monitoring, Physiologic

In order to explore the role of acetylcholine in the pathogenesis of Parkinson's disease (PD), the changes in the concentration of acetylcholine (Ach) in the striatum, the apoptosis of substantia nigra cells, the ultrastructure and the changes of Nissl cells in rats during the morbidity of PD, and the corresponding behaviors in rats with PD were observed. Rat PD model was established by using the modified Thomas method. Eighty-one rats were randomly divided into normal control, sham operation and PD groups and their behavior features were observed at post-operative day (POD) 7, 14 and 21 as three subgroups (n=9 each). The concentration of Ach in the striatum was determined by using high-performance liquid chromatography. The apoptosis of substantia nigra cells was assayed by using TUNEL method. The ultrastructural changes in the substantia nigra were observed under the electron microscopy, and the survival of neurons in the substantia nigra area was examined by using Nissl staining. In PD group at POD 7 to 21, the damage in the substantia nigra area was gradually aggravated, the concentration of Ach, apoptosis rate and turns of rotation were gradually increased, and the number of Nissl cells was gradually reduced over the time as compared with the normal control and sham operation groups (all P<0.05). It was concluded that there exist dynamic changes in Ach concentration, ethology and apoptosis of the substantia nigra cells during the morbidity of PD, suggesting the contribution of apoptosis to the morbidity of PD, and critical role of Ach in the pathogenesis of PD.
Acetylcholine ; pharmacology ; Animals ; Corpus Striatum ; drug effects ; metabolism ; pathology ; Disease Models, Animal ; Male ; Parkinson Disease ; metabolism ; pathology ; Rats ; Rats, Wistar

OBJECTIVEIn vivo Proton Magnetic Resonance Spectroscopy (1H-MRS) can be used to evaluate the levels of specific neurochemical biomarkers of pathological mechanisms in the brain.

METHODSWe conducted T2-Weighted Magnetic Resonance Imaging (MRI) and 1H-MRS with a 3.0-Tesla animal MRI system to investigate the early microstructural and metabolic profiles in vivo in the striatum of rats following carbon monoxide (CO) poisoning.

RESULTSCompared to baseline, we found significant cortical surface deformation, cerebral edema changes, which were indicated by the unclear gray/white matter border, and lateral ventricular volume changes in the brain. A significant reduction in the metabolite to total creatine (Cr) ratios of N-acetylaspartate (NAA) was observed as early as 1 h after the last CO administration, while the lactate (Lac) levels increased marginally. Both the Lac/Cr and NAA/Cr ratios leveled off at 6 h and showed no subsequent significant changes. In addition, compared to the control, the choline (Cho)/Cr ratio was slightly reduced in the early stages and significantly increased after 6 h. In addition, a pathological examination revealed mild cerebral edema on cessation of the insult and more severe cerebral injury after additional CO poisoning.

CONCLUSIONThe present study demonstrated that 1H-MRS of the brain identified early metabolic changes after CO poisoning. Notably, the relationship between the increased Cho/Cr ratio in the striatum and delayed neuropsychologic sequelae requires further research.

Animals ; Biomarkers ; Carbon Monoxide Poisoning ; metabolism ; Corpus Striatum ; drug effects ; metabolism ; Magnetic Resonance Spectroscopy ; methods ; Male ; Rats ; Rats, Sprague-Dawley

Acoustic Stimulation ; Animals ; Corpus Striatum ; physiology ; Estrogens ; metabolism ; Estrus ; physiology ; Evoked Potentials, Auditory ; physiology ; Female ; Rats ; Rats, Sprague-Dawley

The present study is to explore the change process and distribution of phosphorylated DARPP-32 (p-DARPP-32) in rat brain including cortex, hippocampus and striatum and to further deduce whether p-DARPP-32 was possibly involved in epilepsy induced by repetitive low doses of pentylenetetrazol (PTZ). PTZ-induced epilepsy model in rat was established with 30 male SD rats randomly divided into 6 groups, control group and five trial groups [PTZ 1 h, PTZ 6 h, PTZ 24 h, PTZ 48 h and PTZ 72 h respectively, after onset of status epilepticus (SE)]. Immunohistochemistry and immunofluorescence double-labeling were used to detect the temporal time change and distribution of p-DARPP-32 expression and to analyze the coexpression of DARPP-32 and p-DARPP-32 in rat brain after the onset of PTZ-induced generalized SE. The results showed that there was a temporal time change of p-DARPP-32 expression in rat brain after the onset of SE. The number of p-DARPP-32-positive cells increased significantly and reached the peaks at the ends of 1 hour and 6 hours after the onset of SE, but decreased at the end of 24 hours. The moderate to strong p-DARPP-32-immunopositive neurons were observed in cortex, hippocampus and striatum, and located in cell cytoplasm and cell nucleus. Further immunofluorescence double-labeling revealed that denser colocalization of p-DARPP-32 and DARPP-32 in the neurons existed in the area mentioned above. Therefore, PTZ-induced SE may cause phosphorylation of DARPP-32 in rat brain. The temporal time change and distribution of p-DARPP-32 suggest that phosphorylation of DARPP-32 may be involved in PTZ-induced epilepsy in rat brain including cortex, hippocampus and striatum, and p-DARPP-32 may play a central role in the onset of SE.
Animals ; Cerebral Cortex ; metabolism ; Corpus Striatum ; metabolism ; Dopamine and cAMP-Regulated Phosphoprotein 32 ; metabolism ; Hippocampus ; metabolism ; Male ; Neurons ; metabolism ; Pentylenetetrazole ; Rats ; Rats, Sprague-Dawley ; Status Epilepticus ; chemically induced ; metabolism

The aim of this study is to investigate the effect of echinacoside (ECH) on cholinergic neurotransmitter extracellular of hippocampus and striatum and its possible mechanisms of neuro-protective effect against vascular dementia rats. In this study brain microdialysis technique combined with HPLC-IMER-ECD (high-performance liquid chromatography-immobilized enzyme reactor-electrochemical detector) was used. The bilateral common carotid arteries occluded in two times operation at 72 h interval for vascular dementia model rats were used and the successful vascular dementia model rats were examined by Morris water maze. The content of acetylcholine (ACh) and choline (Ch) of microdialysate extracellular of hippocampus and striatum was determined by HPLC-IMER-ECD and the AChE activity in the hippocampus was measured. The results showed that the success rate of vascular dementia model was 83.08% after six weeks; the results also showed that echinacoside and galantamine could increase the content of ACh and reduce the content of Ch extracellular of hippocampus and striatum significantly and the AChE activity increased significantly compared with that of the model group. The results suggested that echinacoside could promote the recovery of cholinergic neurotransmitter levels in vascular dementia rats' brain, which may be one of the mechanisms of neuro-protection.
Acetylcholine ; metabolism ; Animals ; Choline ; metabolism ; Corpus Striatum ; metabolism ; Dementia, Vascular ; metabolism ; Glycosides ; pharmacology ; Hippocampus ; metabolism ; Male ; Neuroprotective Agents ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo evaluate the influence on the synaptic protein expression in different brain regions of ICR mice after lambda-cyhalothrin (LCT) exposure during postnatal period.

METHODSTwo male and 4 female healthy ICR mice were put in one cage. It was set as pregnancy if vaginal plug was founded. Offspring were divided into 5 groups randomly, and exposed to LCT (0.01% DMSO solution) at the doses of 0.1, 1.0 and 10.0 mg/kg by intragastric rout every other day from postnatal days (PND) 5 to PND13, control animals were treated with normal saline or DMSO by the same route. The brains were removed from pups on PND 14, the synaptic protein expression levels in cortex, hippocampus and striatum were measured by western blot.

RESULTSGFAP levels of cortex and hippocampus in the LCT exposure group increased with doses, as compared with control group (P < 0.05), while Tuj protein expression did not change significantly in the various brain regions of ICR mice. GAP-43 protein expression levels in the LCT exposed mouse hippocampus and in female ICR mouse cortex increased with doses, as compared with control group (P < 0.05). Presynaptic protein (Synapsin I) expression levels did not change obviously in various brain regions. However, postsynaptic density protein 95 (PSD95) expression levels of the hippocampus and striatum in male offspring of 10.0 mg/kg LCT group, of cortex of female LCT groups, and of female offspring in all exposure groups, of striatum, in 1.0 or 10.0 mg/kg LCT exposure groups significantly decreased (P < 0.05).

CONCLUSIONSEarly postnatal exposure to LCT affects synaptic protein expression. These effects may ultimately affect the construction of synaptic connections.

Animals ; Animals, Newborn ; Brain ; drug effects ; metabolism ; Corpus Striatum ; drug effects ; metabolism ; Female ; Hippocampus ; drug effects ; metabolism ; Male ; Mice ; Mice, Inbred ICR ; Nitriles ; toxicity ; Pyrethrins ; toxicity ; Synapsins ; metabolism

OBJECTIVETo study the dynamic characteristics of serotonin (5-HT), dopamine (DA) and their metabolin changes in brain during the development of exercise-induced central fatigue.

METHODSCoupling of microdialysis and capillary electrophoresis-laser induced fluorescence detection method were used to continuously monitored the changes of DA, tryptophan (Trp), tyrosine (Tyr), 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in striatum extracellular fluid during the exhaustive exercise and recovery time.

RESULTSThe concentrations of Trp, 5-HT, 5-HIAA in striatum extracellular fluid had no remarkable changes in the early time of exercise (P < 0.05), while they significantly increased during the later time of exercise and whole recovery time (P < 0.05, P < 0.01). The concentrations of DA and Tyr significantly increased over basal level in the later exercise time, exhaust and recovery time (P < 0.05, P < 0.01). DA/5-HT significantly increased in the initial time of exercise (P < 0.05, P < 0.01), while decreased during the later exercise time, the nadir occurred at 15 minutes before rats exhausted. DA/5-HT slightly recovered back to basal level during the recovery time, and there was no significant difference during later exercise, exhausted and recovery time compared with basal level (P < 0.05).

CONCLUSIONThe changes of DA and 5-HT in striatum have phase characteristics. Both of them significantly increase during the development of exercise-induced fatigue. However, the 5-HT plays the dominant role in the dynamic changes of them.

Animals ; Corpus Striatum ; metabolism ; Dopamine ; metabolism ; Fatigue ; metabolism ; physiopathology ; Male ; Physical Conditioning, Animal ; physiology ; Physical Exertion ; physiology ; Rats ; Rats, Wistar ; Serotonin ; metabolism