Emerging Policy Issues and Research Priorities on Western Hemisphere Integration

International Relations/Trade,

GLOBAL CHALLENGES: LOCAL ISSUES

International Development,

HOW POLICY DECISIONS ARE MADE IN CANADIAN AGRICULTURE

Agricultural and Food Policy,

Effects of thyroliberin on mammalian neurotransmitter biochemistry

Thyroliberin (TRH) has been shown in a number of laboratories to have behavioural effects in animals unconnected with its endocrine function. Pharmacological studies have suggested the involvement of dopaminergic neurones in some of the observed effects and cholinergic neurones in others. Many of the behavioural effects of TRH in rodents appear to originate in the nucleus accumbens and septum brain regions. In this thesis the effects of TRH, one of its metabolites (cyclo HisPro) and a TRH-analogue (CG3703) on the release of dopamine and acetylcholine from rat brain tissue preparations were investigated. TRH (10-6--10-3M) stimulated the release of (3H)-dopamine from tissue-cube and P2 preparations of rat nucleus accumbens and striatum in a manner sensitive to the pH (pH 6.5 > pH7.4) and composition of the incubation medium. Cyclo-HisPro (1mM) stimulated the release of (3H)-dopamine from P2 preparations of nucleus accumbens and striatum at pH 6.5 but appeared to be no more potent than TRH in its effects. CG3703 (10-6--10-3M) stimulated the release of (3H)-dopamine from tissue cubes of rat nucleus accumbens at pH 6.5 but not at pH 7.4. Neither TRH nor its analogues (0.1mM) had any consistent effect on the release of (3H)-acetylcholine or (3H)-choline from tissue cubes of nucleus accumbens or septum at pH 7.4. 50mM-KCl in all cases stimulated the release of (3H)-dopamine from tissue preparations of nucleus accumbens and striatum at pH 6.5 and 7.4 and of both (3H)-acetylcholine and (3H)-choline from nucleus accumbens and septum. These results suggest that the stimulation of release of dopamine by TRH arise from a direct intaraction of the peptide with dopaminergic neurones, not by a modulation of dopamine release caused by TRH affecting release of acetylcholine. The increased potency of cycloHisPro and CG3703 relative to TRH in behavioural paradigms may result from their resistance to degradation

Exploring the self-assembly and energy transfer of dynamic supramolecular iridium-porphyrin systems

EZ-C acknowledges the University of St Andrews for financial support. IDWS acknowledges support from EPSRC (EP/J009016) and the European Research Council (grant 321305). IDWS also acknowledges support from a Royal Society Wolfson research merit award. DJ acknowledges the European Research Council (grant: 278845) and the RFI Lumomat for financial support.We present the first examples of dynamic supramolecular systems composed of cyclometalated Ir(III) complexes of the form of [Ir(C^N)2(N^N)]PF6 (where C^N is mesppy = 2-phenyl-4-mesitylpyridinato and dFmesppy = 2-(4,6-difluorophenyl)-4-mesitylpyridinato and N^N is 4,4':2',2'':4'',4'''-quaterpyridine, qpy) and zinc tetraphenylporphyrin (ZnTPP), assembled through non-covalent interactions between the distal pyridine moieties of the qpy ligand located on the iridium complex and the zinc of the ZnTPP. The assemblies have been comprehensively characterized by a series of analytical techniques (1H NMR titration experiments, 2D COSY and HETCOR NMR spectra and low temperature 1H NMR spectroscopy) and the crystal structures have been elucidated by X-ray diffraction. The optoelectronic properties of the assemblies and the electronic interaction between the iridium and porphyrin chromophoric units have been explored with detailed photophysical measurements, supported by time-dependent density functional theory (TD-DFT) calculations.PostprintPeer reviewe