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Objective To evaluate the effect of amitriptyline on the phosphorylation of histone deacetylase 5 (HDAC5) in the basolateral amygdala (BLA) of rats with neuropathic pain.Methods Thirty healthy male Wistar rats,weighing 250-300 g,were divided into 3 groups (n=10 each) using a random number table method:sham operation group (S group),neuropathic pain group (NP group) and amitriptyline group (A group).Spared nerve injury was produced by exposing the sciatic nerve and its branches and ligation and transection of tibial nerve and common fibular nerve in anesthetized rats.Amitriptyline 10 mg/kg was intraperitoneally injected every day on 14-35 days after establishing the model in group A,while the equal volume of normal saline was given instead of amitriptyline in S and NP groups.The mechanical paw withdrawal threshold (MWT) was measured on 3,7,14,21,28 and 35 days after establishing the model in each group.The forced swimming test was performed on day 36 after establishing the model,and immobility time,climbing time and swimming time were recorded.The rats were then sacrificed,and brain tissues in BLA were obtained for determination of the expression of HDAC5 and phosphorylated HDAC5 (p-HDAC5) (by Western blot) and expressionof HDAC5 mRNA (by real-time quantitative polymerase chain reaction).Results Compared with group S,the MWT was significantly decreased at each time point,the immobility time was prolonged,and the swimming time and climbing time were shortened in group NP,and the MWT was significantly decreased on days 14,21 and 28 after establishing the model,the expression of p-HDAC5 was down-regulated,and the expression of HDAC5 mRNA was up-regulated in group A (P＜0.05).Compared with group NP,the MWT was significantly increased on days 21,28 and 35 after establishing the model,the immobility time was shortened,the climbing time was prolonged,the expression of p-HDAC5 was up-regulated,and the expression of HDAC5 mRNA was down-regulated in group A (P＜0.05or 0.01).Conclusion The mechanism by which amitriptyline improves depression is associated with promoting the phosphorylation of HDAC5 in BLA of rats with NP.
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OBJECTIVES: Previous studies have revealed inconsistent results on amygdala volume in adult bipolar disorder (BD) patients compared to healthy controls (HC). Since the amygdala encompasses multiple subregions, the subtle volume changes in each amygdala nucleus might have not been fully reflected in the measure of the total amygdala volume, causing discrepant results. Thus, we aimed to investigate volume changes in each amygdala subregion and their association with subtypes of BD, lithium use and clinical status of BD. METHODS: Fifty-five BD patients and 55 HC underwent T1-weighted structural magnetic resonance imaging. We analyzed volumes of the whole amygdala and each amygdala subregion, including the anterior amygdaloid area, cortico-amygdaloid transition area, basal, lateral, accessory basal, central, cortical, medial and paralaminar nuclei using the atlas in the FreeSurfer. The volume difference was analyzed using a one-way analysis of covariance with individual volumes as dependent variables, and age, sex, and total intracranial volume as covariates. RESULTS: The volumes of whole right amygdala and subregions including basal nucleus, accessory basal nucleus, anterior amygdaloid area, and cortico-amygdaloid transition area in the right amygdala of BD patients were significantly smaller for the HC group. No significant volume difference between bipolar I disorder and bipolar II disorder was found after the Bonferroni correction. The trend of larger volume in medial nucleus with lithium treatment was not significant after the Bonferroni correction. No significant correlation between illness duration and amygdala volume, and insignificant negative correlation were found between right central nucleus volume and depression severity. CONCLUSIONS: Significant volume decrements of the whole amygdala, basal nucleus, accessory basal nucleus, anterior amygdaloid area, and cortico-amygdaloid transition area were found in the right hemisphere in adult BD patients, compared to HC group. We postulate that such volume changes are associated with altered functional activity and connectivity of amygdala nuclei in BD.