Boonrit Thongsong

Inhibition of Amino Acid Transport System A by Interleukin-1β in Trophoblasts

Objective: The current study sought to investigate the influence of interleukin-1β (IL-1β) on the function of the amino acid transport system A in trophoblasts. Methods: BeWo choriocarcinoma cells were exposed to recombinant human IL-1β in serum-free medium. Cells incubated with serum-free medium in the absence of IL-1β were used as control. System A activity was determined in control and treated cells by measuring the uptake of α-(methylamino)isobutyric acid. The results obtained were confirmed by measuring system. A activity in placental brush border membrane vesicles isolatewd from pregnant rats injected with IL-1β. Results: Treatment of BeWe cells with IL-1β resulted in a time- and dose- dependent inhibition of system A. Treatment with IL-1β also inhibited the uptake of arginine, and glutamate but had no significant effect on the uptake of leucine, tryptophan, and ascorbate. The inhibition of system A activity by IL-1β was abolished in the presence of IL-1β receptor antagonist. The inhibitory effect was associated with a decrease in the maximal velocity of the transport system with no effect on the substrate affinity. Steady-state levels of both SNAT1 and SNAT2 mRNA were reduced by IL-1β treatment as evidenced by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. In rat placental brush border membrane vesicles isolated from IL-1β-treated pregnant rats, system. A activity was found to be decreased by approximately 40% compared to activity in control membrane vesicles. Conclusions: IL-1β decreases SNAT1 and SNAT2 mRNA levels in trophoblasts, which is associated with a decrease in system A-mediated transport activity at the functional level. These findings may have important consequences under both physiologic conditions and pathologic conditions during pregnancy that are associated with elevated levels of IL-1β.

Effects of time of estrogen deprivation on anxiety-like behavior and GABAA receptor plasticity in ovariectomized rats

Ovariectomized animals have frequently been used to study the effects of estrogen deficiency on mood disorders, particularly anxiety disorder. However, a range of results including anxiolytic, anxiogenic, and no behavioral effects have been reported. One discrepancy was the different in behavioral testing time following ovariectomized; therefore, the aim of this study was to examine the effects of time of estrogen deprivation on anxiety-like behavior and on GABAA receptor subunit gene expressions in ovariectomized rats. The GABAA receptor was of special interest as it had been shown to be influenced by estrogen. In this study, adult female Wistar rats were ovariectomized and randomly assigned into 2 groups: ovariectomized-rat (Ovx) and ovariectomized-rat treated with estrogen (E2) at the dosage of 1μg/kg BW. At 7, 14, 21 and 28 days after ovariectomy, the rats were tested with elevated T-maze (ETM) and open field. We found that after ovariectomy, the Ovx showed signs of anxiety as demonstrated by the increased in inhibitory avoidance latency in the ETM with significant effect at day 21 and even higher at day 28. On the other hand, the escape latency was not differed between each time point. These behavioral data implied that the anxiety in term of generalized anxiety disorder as interpreted from impaired inhibitory avoidance in the ETM was affected by estrogen depletion; while, the anxiety disorder in term of panic disorder as shown by escape latency was unaffected. For gene expression analysis, the GABAA receptor α2-, α3- and α4-subunits in Ovx groups were significantly increased in the midbrain compared to E2 groups; whereas, in the amygdala, the gene expressions were not different between Ovx and E2 groups. In conclusion, these results indicated that ovariectomized as early as 21 day can induce anxiety and the altered GABAA receptor subunit may be partially responsible for anxiety following estrogen deprivation.