OBJECTIVETo explore the role of µ-opioid receptors (MOR) in the central nucleus of the amygdala (CeA) in modulating sucrose solution intake in rats.

METHODSSprague-Dawley rats received intra-CeA injection of MOR agonist DAMGO or saline, and then underwent two bottle choice test between sucrose solution and distilled water. After intake of sucrose solution or distilled water, activated neurons in the CeA were labeled and identified with MOR/Fos-double labeling immunohistochemistry.

RESULTSCompared with saline injection, intra-CeA injection of DAMGO significantly increased sucrose solution intake in rats over a 3-h period. Sucrose solution intake induced significantly more c-Fos and MOR/Fos double-labeled neurons in the CeA than distilled water intake.

CONCLUSIONSThe CeA participates in modulation of sucrose intake in rats, and MOR may partly mediate this mechanism.

Amygdala ; metabolism ; Animals ; Male ; Neurons ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, mu ; metabolism ; Sucrose ; metabolism

Epilepsy is a common neurological disorder characterized by hyperexcitability in the brain. Its pathogenesis is classically associated with an imbalance of excitatory and inhibitory neurons. Calretinin (CR) is one of the three major types of calcium-binding proteins present in inhibitory GABAergic neurons. The functions of CR and its role in neural excitability are still unknown. Recent data suggest that CR neurons have diverse neurotransmitters, morphologies, distributions, and functions in different brain regions across various species. Notably, CR neurons in the hippocampus, amygdala, neocortex, and thalamus are extremely susceptible to excitotoxicity in the epileptic brain, but the causal relationship is unknown. In this review, we focus on the heterogeneous functions of CR neurons in different brain regions and their relationship with neural excitability and epilepsy. Importantly, we provide perspectives on future investigations of the role of CR neurons in epilepsy.
Amygdala/metabolism* ; Calbindin 2/metabolism* ; Epilepsy ; GABAergic Neurons ; Hippocampus/metabolism* ; Humans

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

Amygdala ; drug effects ; metabolism ; Animals ; Conditioning (Psychology) ; Morphine ; adverse effects ; Rats ; Receptors, Opioid, kappa ; metabolism

OBJECTIVES: To explore the damage effects of chronic restraint stress (CRS) on amygdala cells through the rat CRS model. METHODS: The rat CRS model was established, and the changes in body weight and adrenal mass in control group and CRS group were monitored at 1 d, 7 d, 14 d and 21 d. The behavior changes were evaluated by the percentage of retention time of open arms and open arm entries using the elevated plus maze (EPM). ELISA was used to detect the concentrations of rat's corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol. The changes of expression of glucocorticoid receptor (GR) and glial fibrillary acidic protein (GFAP) in amygdala were determined by immunohistochemistry and Western blotting. Ultrastructure changes of glial cell were observed by transmission electron microscopy. The apoptosis rate of amygdala was measured by flow cytometry. RESULTS: Compared with the control group at the same time points, body weight of CRS 1 d, 7 d, 14 d and 21 d groups increased slowly, but adrenal mass increased significantly; the serum level of CRH, cortisol and ACTH increased significantly at 7 d, 14 d and 21 d respectively; the expression of GR in amygdala was increased while that of GFAP was decreased; EPM test suggested that the percentage of retention time of open arms and open arm entries decreased significantly after 14 d. The CRS group showed different degrees of glial cell damage in amygdala, and the apoptosis rate of glial cell was significantly increased in 21 d group. CONCLUSIONS This study successfully established a CRS model in rats, and anxiety-like behavioral changes in model rats may be caused by apoptosis of amygdala astrocytes.
Rats ; Animals ; Hydrocortisone/pharmacology* ; Amygdala/metabolism* ; Adrenocorticotropic Hormone/pharmacology* ; Apoptosis ; Body Weight

OBJECTIVETo determine whether the GABA-containing neurons in rat central nucleus of amygdala (CeA) can be activated by acute sodium deprivation.

METHODSAcute sodium depletion was induced by subcutaneous injection of furosemide in rats followed by 24 h of dietary sodium deprivation. The rats underwent 0.3 mol/L NaCl/distilled water two bottle choice test, and the activated neurons were labeled and identified with GABA/Fos-double labeling immunohistochemistry.

RESULTSThe rats with acute sodium depletion exhibited significantly more numerous c-fos-positive neurons and GABA/Fos double-labeled neurons in the CeA than the control group (P<0.01, P<0.05). Consumption of 0.3 mol/L NaCl significantly increased the number of c-fos and GABA/Fos double labeled neurons compared to the distilled water group (P<0.001, P<0.01).

CONCLUSIONGABAergic neurons in the CeA may play an inhibitory role in the regulation of sodium intake in rats with acute sodium depletion.

Amygdala ; cytology ; metabolism ; Animals ; GABAergic Neurons ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Sodium Chloride, Dietary ; metabolism ; Sodium, Dietary

OBJECTIVE: To investigate the underlying molecular mechanisms by which silence information regulator (SIRT) 2 and glutaminase (GLS) in the amygdala regulate social behaviors in autistic rats. METHODS: Rat models of autism were established by maternal sodium valproic acid (VPA) exposure in wild-type rats and SIRT2-knockout ( SIRT2 ^-/-) rats. Glutamate (Glu) content, brain weight, and expression levels of SIRT2, GLS proteins and apoptosis-associated proteins in rat amygdala at different developmental stages were examined, and the social behaviors of VPA rats were assessed by a three-chamber test. Then, lentiviral overexpression or interference vectors of GLS were injected into the amygdala of VPA rats. Brain weight, Glu content and expression level of GLS protein were measured, and the social behaviors assessed. RESULTS: Brain weight, amygdala Glu content and the levels of SIRT2, GLS protein and pro-apoptotic protein caspase-3 in the amygdala were increased in VPA rats, while the level of anti-apoptotic protein Bcl-2 was decreased (all P<0.01). Compared with the wild-type rats, SIRT2 ^-/- rats displayed decreased expression of SIRT2 and GLS proteins in the amygdala, reduced Glu content, and improved social dysfunction (all P<0.01). Overexpression of GLS increased brain weight and Glu content, and aggravated social dysfunction in VPA rats (all P<0.01). Knockdown of GLS decreased brain weight and Glu content, and improved social dysfunction in VPA rats (all P<0.01). CONCLUSIONS The glutamate circulatory system in the amygdala of VPA induced autistic rats is abnormal. This is associated with the upregulation of SIRT2 expression and its induced increase of GLS production; knocking out SIRT2 gene or inhibiting the expression of GLS is helpful in maintaining the balanced glutamate cycle and in improving the social behavior disorder of rats.
Animals ; Rats ; Amygdala/metabolism* ; Autistic Disorder/metabolism* ; Behavior, Animal ; Disease Models, Animal ; Glutamates/metabolism* ; Glutaminase/metabolism* ; Sirtuin 2/metabolism* ; Social Behavior

OBJECTIVE: To observe the expression of discs large homolog 4 (DLG4) protein in hippocampus, amygdala and frontal cortex of rats and evaluate postsynaptic density in heroin dependence. METHODS: The rat heroin dependent model was established by increasing intraperitoneal injection of heroin. DLG4 proteins in hippocampus, amygdala and frontal cortex of heroin dependent 9, 18, 36 days rats were detected with immunohistochemical staining and compared with that in the control group. RESULTS: DLG4 proteins in hippocampus, amygdala and frontal cortex were gradually reduced with extension of heroin dependent time. CONCLUSION Heroin dependence can affect postsynaptic density of hippocampus, amygdala and frontal cortex. The changes become more apparent with extension of heroin dependence time.
Amygdala/metabolism* ; Animals ; Disks Large Homolog 4 Protein ; Frontal Lobe/metabolism* ; Heroin/pharmacology* ; Heroin Dependence ; Hippocampus/metabolism* ; Injections, Intraperitoneal ; Intracellular Signaling Peptides and Proteins/metabolism* ; Membrane Proteins/metabolism* ; Rats

This study was aimed to optimize the methods of magnetic resonance spectroscopy (MRS) to improve its quality in amygdala. Forty-three volunteers were examined at right and left amygdala using stimulated-echo acquisition mode (STEAM), and point-resolved spectroscopy series (PRESS) with and without saturation bands. The Cr-SNR, water-suppression level, water full width at half maximum (FWHM) and RMS noise of three sequences were compared. The results showed that (1) the Cr-SNR and water-suppression lelvel of PRESS with saturation bands were better than that of PRESS without saturation bands and STEAM (P<0.001); (2) the left and right RMS noise was significantly different both using PRESS with saturation bands and using STEAM (P<0.05); (3) there was a positive, significant correlation between Cr-SNR and voxel size (P<0.05). Therefore, PRESS with saturation bands is better than PRESS without saturation bands or STEAM for the spectroscopy of amygdala. It is also useful to make the voxel as big as possible to improve the spectral quality.
Adult ; Algorithms ; Amygdala ; metabolism ; physiology ; Artifacts ; Female ; Humans ; Magnetic Resonance Spectroscopy ; methods ; Male ; Pattern Recognition, Automated ; standards ; Young Adult

Norepinephrine (NE)-containing locus ceruleus (LC) has been known to participate in the regulation of the sleep-wake cycle according to the differential firing rate. The aim of this study was to know the change of extracellular NE level in the rat amygdala, which are reciprocally connected with LC, during sleep-wake-fulness. Extracellular NE levels in the rat amygdala were inrestigated during different stages of the sleep-waking cycle using in vivo microdialysis and polygraphic recording. Dialysates were collected every 5 min and correlated with the results of polygraphic recording. The content of NE was measured by high-performance liquid chromatography with electrochemical detection. NE level was the highest in active waking (AW) and, when compared to AW, NE level was progressively lower in quiet waking (QW; 86%), quiet sleep (QS; 72%), and active sleep (AS or REM sleep; 61%). This result suggests that the rat amygdala also participates in the regulation of the sleep-wake cycle according to the differential NE release.
Amygdala/*metabolism ; Animals ; Arousal/*physiology ; Electroencephalography ; Extracellular Space/metabolism ; Locus Coeruleus/metabolism ; Male ; Microdialysis ; Norepinephrine/*metabolism ; Rats ; Rats, Sprague-Dawley ; Sleep/*physiology