SHELL Part of Nucleus Accumbens and Its Laterality Has Important Role in Response to Chronic Stress in Female Rats

Abstract The nucleus accumbens shell (NAcSh) plays a role in appetitive and negative motivation with sex differences in responses. NAcSh and its laterality in metabolic and hormonal responses to chronic stress in female rats is evaluated via transient inactivation of this nucleus during stress induction. Animals in the stress groups received consecutive stress for four days and transient inactivation of NAcSh was performed by administrating lidocaine (0.2%) unilaterally or bilaterally in the nucleus for five minutes before electric foot shock induction. After stress termination, food and water intake, latency to eat, plasma glucose, corticosterone, estradiol and progesterone were measured in all groups. Results showed that stress increased food intake and blood glucose level, but there were no change in the latency to eat and the amount of water intake. The right side, the left side, and both sides of NAcSh may be dominant in latency to eat, food intake, and both water intake and plasma glucose level, respectively. Although chronic stress included no changes for corticosterone and progesterone, it increased estradiol level in plasma. Also, bilateral and right sides of NAcSh may have modulatory effects on stress in corticosterone and progesterone, respectively, without affecting estradiol. It can be concluded that the NAc shell plays a pivotal role in metabolic and hormonal responses to chronic stress in a laterality manner in female rats.

Transient inactivation of the nucleus accumbens (NAc) shell prominently ameliorates responses to acute stress in female rats.

It is clear that the stress response differs between females and males. Moreover, the nucleus accumbens shell is considered a critical area in the brain's response to stress. In the present study we investigate the effect of the transient inactivation of the NAc shell on the metabolic and hormonal disturbance induced by acute stress in female rats. Female Wistar rats were canulated uni- or bilaterally in the NAc shell before stress induction. Electric foot shock was applied to the animals and lidocaine hydrochloride was administered intra-acumbally 5min before each stress session. Food and water intake, delay to eating time, plasma corticosterone, estradiol and progesterone were measured after stress administration. Our results indicate that food intake increased whereas water intake decreased in stress group, furthermore, delay in the onset of eating also was observed. In addition, plasma corticosterone and progesterone concentrations were increased whereas estradiol was decreased. Transient inactivation of right side of NAc shell inhibited the stress effect on food intake; however, the effect of stress was exacerbated when the left part of the NAc shell was inhibited. Transient inactivation of both NAc shell sides augmented the stress effect on water intake. The same results also obtained for the effect of stress on delay to eating time. Lidocaine administration inhibited the effects of stress on all of the hormones we tested. It can be concluded that the NAc shell plays an important role in the mediation of stress responses in female rats and this influence shows asymmetrical manner.

Influence of motion pattern on apical transportation and centering ability of WaveOne single-file technique in curved root canals.

BACKGROUND: The aim of this study was to evaluate apical transportation and centering ability of single-file instruments, WaveOne primary, with full rotation versus reciprocation movement using cone-beam computed tomography (CBCT) analysis in curved mesiobuccal (MB) root canal of human mandibular molars. MATERIALS AND METHODS: Thirty MB canals of mandibular molars were randomly divided into two groups according to the instrument motion (n = 15): Group 1, reciprocation/WaveOne primary; Group 2, continuous rotation/WaveOne primary. After preparation, the amount of apical transportation and centering ability were assessed by evaluating pre- and post-instrumentation CBCT scans in three section (1, 3, and 5 mm from apical foramen). Statistical analysis of the data was performed using Mann-Whitney U-test and Friedman test (α = 0.05). RESULTS: There was no statistically significant difference between two experimental groups in terms of apical transportation and centering ratio at 1, 3, and 5 mm from apical foramen (P > 0.05). CONCLUSION: Apical transportation and centering ability of WaveOne primary reciprocating instrument did not significantly differ between two motion patterns.

Alterations of the Danger Zone after Preparation of Curved Root Canals Using WaveOne with Reverse Rotation or Reciprocation Movements.

INTRODUCTION: The aim of this study was to compare the changes that occur in the danger zone (DZ) after preparation of curved mesiobuccal (MB) canals of mandibular first molars with WaveOne instruments in two different movements [reciprocation (RCP) and counter-clockwise rotation (CCWR)] by means of cone-beam computed tomography (CBCT). METHODS AND MATERIALS: MB canals of 30 mandibular molars were randomly divided into 2 groups (n=15); WaveOne/RCP and WaveOne/CCWR. Pre- and post-instrumentation CBCT images were assessed for changes in the dentin thickness in DZ (2 and 4 mm below the highest point of the root furcation) in both groups. Data was analyzed using the repeated measures ANOVA test. RESULTS: There was no statistically significant difference between two experimental groups in terms of remaining dentin thickness at 2 and 4 mm levels below the highest point of the furcation (P>0.05). CONCLUSION: The efficacy of WaveOne instrument on changes of the dentin thickness in the DZ was not affected by different file movements.

Keratoameloblastoma, a very rare variant of ameloblastoma.

The keratoameloblastoma is a rare histologic variant of ameloblastoma. Fewer than 15 cases of keratoameloblastoma have been documented in the literature. We report a new case of keratoameloblastoma in a 21-year-old female patient with a unilocular radiolucent lesion between the roots of the right mandibular incisors. We describe the clinical, radiographic, and histopathologic features of this lesion along with a review on the characteristics of previous cases. We also discuss about classification and management of this lesion.