Prolonged effects of repeated social defeat stress on mRNA expression and function of mu-opioid receptors in the ventral tegmental area of rats.

Social defeat stress alters the activity of mesocorticolimbic dopamine projections from the ventral tegmental area (VTA), a process that has been implicated in the development of sensitization and drug-seeking behavior. We showed previously that acute brief social defeat stress increased short-term expression of mu-opioid receptor mRNA in the VTA. The present study assessed the presence and functional significance of mu-opioid receptor mRNA expression 1 week after the last episode of social defeat stress. Social defeat stress was induced in intruder rats during short confrontations with an aggressive resident rat, and subsequent exposures behind a protective screen once a day for 5 days. Regional mu-receptor mRNA levels were assessed by in situ hybridization histochemistry, and the amount of mRNA labeling was measured in the VTA and the substantia nigra (SN). Expression of mu-opioid receptor mRNA was significantly higher in defeated rats relative to handled control animals in the VTA, but not in the SN. In an additional group of rats, bilateral local intra-VTA injection of the selective mu-opioid receptor agonist DAMGO (1.0 microg per side) was performed 7-10 days after the last defeat stress or handling control procedure. Baseline motor activity did not differ between control and stressed rats. Intra-VTA DAMGO significantly increased locomotor activity in stressed rats compared to handled control rats. These results suggest that repeated social stress upregulates VTA mu-opioid receptors and can produce locomotor activation via stimulation of these receptors. This locomotor effect is probably the consequence of enhanced disinhibition of mesolimbic dopamine neurons.     

A retrospective examination of regional plus general anesthesia in children undergoing open heart surgery

The use of regional anesthesia in combination with general anesthesia for children undergoing cardiac surgery is receiving increasing attention from clinicians. The addition of regional anesthesia may improve clinical outcomes and decrease costs as a result of the reduced need for postoperative mechanical ventilation. The goal of this retrospective chart review was to evaluate whether spinal anesthesia (SAB) or epidural anesthesia (EPID) in combination with general anesthesia was associated with circulatory stability, satisfactory postoperative sedation/analgesia, and a low incidence of adverse effects. The medical records of 50 consecutive children having open heart surgery with SAB or EPID and general anesthesia between September 1996 and December 1997 were reviewed. We found no significant differences in the incidence of clinically significant changes in vital signs, oxygen desaturation, hypercarbia, or vomiting. Patients in the SAB group received significantly more sedative/analgesic interventions than those in the EPID group.     

Mono- and Diterpenes from Cell Cultures of Thuja occidentalis

Cell cultures of THUJA OCCIDENTIALIS L. were found to biosynthesize various mono- and diterpenes when grown on B5-medium. The identification of the constituents was achieved mainly by capillary GLC-MS using fused silica columns and E.I.-mass spectrometry. Monoterpenes of the menthane type were only isolated from the culture medium whereas diterpenes were found in the cell extracts. Thujaplicin derivatives, monoterpenes of an irregular type, were detected in the medium as well as in the cells. Major differences were found between the terpene composition of the cell culture extracts and those from THUJA leaves. The cell cultures accumulated some compounds which are presently unknown as constituents of THUJA plants. On the other hand, the cultures were evidently unable to synthesize the thujone type of monoterpenes.