Arginine vasopressin (AVP), released from the CNS, plays an important role in regulating several aspects of CNS functions including aggression, anxiety, and cognition. In this study, we report a novel finding that AVP induces glutamate release from astrocytes isolated from the cerebral cortex and hippocampus. We also investigated the types of AVP receptors involved in the AVP-induced increase in glutamate release from astrocytes isolated from the hippocampus and cortex of neonatal rats. We showed that the AVP (0.1-1000 nmol/L) induced increase in glutamate release and [Ca 2+ ] i is brought about by two distinct subtypes of V 1 receptors (V 1a and V 1b ). Our results suggested that V 1b receptors are predominantly expressed in astrocytes isolated from the hippocampus and V 1a receptors are solely expressed in astrocytes isolated from the cerebral cortex of neonatal rats. The results of the western blot analyses confirmed these pharmacological data. In addition, the AVP-induced increase in glutamate did not contribute to an increase in [Ca 2+ ] i , as blockade of metabotropic glutamate receptors did not alter the AVP-induced increase in [Ca 2+ ] i . In addition, the administration of a phospholipase A 2 inhibitor failed to alter AVP-induced [Ca 2+ ] i increase suggesting the lack of involvement of this enzyme. Keywords: cerebral cortex, glutamate release, hippocampus, phospholipase A 2 , V 1a receptors, V 1b receptors.
Introduction: Recent years have shown an increase in the number of patients referred from primary care to a secondary care setting for oral surgery treatment. Due to the high volume of referrals to specialist Oral Surgery services, it is paramount that the referrals from dentist to specialists be appropriate and of a high standard. Materials and methods: The first part of this study assessed patients referred to two primary care settings for oral surgery procedures in Manchester, UK, and the second part examined the quality of the referrals undertaken.
Somatostatin (SS) is a peptide hormone that inhibits insulin secretion inThese findings suggested that Arf6, but not Arf1 or Arf5, mediates the effect of SS. We further determined the involvement of the Arf6 guanine nucleotide exchange factor (GEF) EFA6A, a GEF previously thought to be found predominantly in the brain, in the activation of PLD1 in HIT-T15 cells. Using Northern and Western blot analyses, both mRNA and protein of EFA6A were found in these cells. Overexpression of dn-EFA6A mutant, EFA6A(E242K), and suppression of mRNA levels using siRNA, both abolished SS-induced PLD activation, whereas overexpression of dn-EFA6B mutant, EFA6B(E651K), failed to reduce SS-induced PLD activation. In addition, overexpression of dn-ARNO mutant, ARNO(E156K), another GEF of Arf6, had no effect on SS-induced activation of PLD. Taken together, these results suggest that SS signals through EFA6A to activate Arf6-PLD cascade.
Chapter 1. General Introduction 1 Thesis Organization 1 Literature Review 1 References Chapter 2. Arginine vasopressin increases glutamate release and intracellular Ca 2+ concentration in hippocampal and cortical astrocytes through two distinct receptors Abstract 37 Materials and Methods Results Discussion 45 References Chapter 3. Somatostatin inhibits forskolin-induced increase in cyclic AMP levels, intracellular Ca 2+ and glutamate release via SSTR4 in rat astrocytes 66
Mineral Trioxide Aggregate (MTA) is a dental material which allows a one-visit apexification and is considered an effective alternative to calcium hydroxide. It is important for the whole dental team to understand the clinical techniques used and the materials involved.
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