The role of AE3 in the production of GABAergic excitation by chronic hyperosmotic stress and chronic lactation in hypothalamic magnocellular neurons of the rats

다국어 초록 (Multilingual Abstract)

[Back ground] In general, the activation of GABAA receptor by GABA has been known to produce inhibitory signals in the neurotransmission system. Yet, arginine vasopressin (AVP) and oxytocin neurons under chronic hyperosmotic stress and chronic lactation state switch their GABAergic transmission from inhibitory to excitatory via up-regulation of the Cl−-importing mechanisms and reverse the potential of GABAergic response (EGABA). In particular, this study focuses on to provide evidence that anion exchanger 3 (AE3) may be one of the key mechanistic factors in the up-regulation of the Cl−-importing pathway.
[Methods and Results] In order to verify the contribution of anion exchanges (AEs) in the process of Cl− uptake, 4,4'-diisothiocyano-2,2'-stilbene-disulfonic acid (DIDS), AE inhibitor, was used in the MNC neurons of rats under chronic hyperosmotic stress and chronic lactation state. The EGABA’s of MNC neurons recorded in the absence and the presence of DIDS were compared to show the contributions of AE3 in the depolarizing shift of EGABA in the MNC neurons of examined rats. In addition, western blot experiment was also conducted to illustrate the increased expression of AEs in the supraoptic nucleus (SON) under the chronic hyperosmotic stress.
[Discussion] This study demonstrates that in response to particular physiological needs, GABA can switch from functioning as an inhibitory transmitter to evoking an excitatory response in the MNC via shifting from inhibitory to excitatory transmission in postsynaptic neurons through the long-term regulation of the Cl- uptake mechanisms, including AE3.

목차 (Table of Contents)

• TABLE OF CONTENTS
• I. Introduction 6
• II. Method 7
• 1. Animal care 7
• 2. Hydration and lactation states of animals 7
• 3. Hypothalamic slice preparation 8
• 4. Intracellular recording 8
• 5. Gramicidin-perforated patch technique 9
• 6. Electrical stimulation for elicitation of GABAergic postsynaptic responses 10
• 7. Western blot 10
• 8. Immunohistochemistry 11
• 9. Statistical analysis 12
• III. Results 13
• IV. Discussion 16
• V. Reference 19
• VI. Figures and Tables 21
• Figure 1. GABAA receptor-mediated excitatory and inhibitory PSPs in hypothalamic MNCs 21
• Figure 2. Effects of bumetanide and 4,4'-diisothiocyano-2,2'-stilbene-disulfonic acid (DIDS) on EGABA in the MNCs of rats in different hydration and lactation states 22
• Figure 3. Western blot analyses of AE3 in the SON 23
• Figure 4. Immunohistochemical detection of AE3 in the SON 24
• Table I. GABAergic PSP profiles of MNCs in different groups of rats 25
• VII. Abstract 26