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Asymmetric synthesis of LY354740: A highly potent and selective group 2 mGluR agonist
41
42
ASYMMETRIC SYNTHESIS OF LY354740: A HIGHLY POTENT AND SELECTIVE GROUP 2 mGluR AGONIST CarmenDomfnguez*L. Jestis Ezquerra’. Modesta Espada*, Carmen Pedrega12. Lourdes P&d. 1 Centro de Investigaci6n Lilly S.A. Paraje de la Cruz s/n. 28130Valdeolmos. Madrid. Spain. 2 Departamento de Quimica Organica y Farmacnitica. Fact&ad de Farmacia. Universidad Complutense. 28040-Madrid. Spain.
PRESYNAPTIC
The amino diacid (t)-2.aminobicyclo[3.l,O]hexane-2,6dicarboxylate, LY314582. is a highly potent and selective group 2 metabotropic glutamate receptor agonist. The group 2 mGluR agonist activity of LY314582 has been found to reside in the (+) enamiomer, LY354740. obtained by classical resolution methodologies. We report here an asymmetric synthesis of LY354740. The key intermediate is Ihe cyclopentenone 1. obtained from the commercially available sugar lactone D(+)-ribonic lactonel. From this work, the absolute stereochemistry of LY354740 has been established as lS, 2S, 5R. 6s.
D(+)-Ribonic lactone
1
LY 354740
1 Borcherding, D.R.. Scholtz. S.A., Borchard. R.T. J.Org.Chem. 52, 5457 (1987).
OF EPSPs IN LOCUS
44
43 mGluR8 FUNCTION REl’ORT
INHIBITION
COERULEUS BY MULTIPLE mGluRs G. R. Dub& and KC. Marshall Dept. of Physiology. University of Ottawa, Ottawa, Canada. Activation of metabotropic glutamate receptors (mGluRs) by L-AP4 or r-ACPD (EC,s of 0.92 and 9.2 pM respectively) resulted in an inhibition of excitatory postsynaptic potentials (EPSPs) in intracellularly recorded locus coeruleus (LC) neurons in brain slice preparations (Dub& and Marshall, 1995, Sot. Neurosci. Abstr.). This inhibition was not observed with the potent and specific group I mGluR agonist DHPG (100 ILM). Several additional tests have been made to characterize the locus of action and the mGluR subtype(s) involved in this inhibition. Combined application of LAP4 (10 @f) and r-ACPD (30 pM), caused a significantly greater inhibition than that observed with either one alone. Both agonists produced an increase in paired-pulse facilitation, and failed lo change the LC response to focally applied glutamate, indicating a presynaptic locus of action. The L-AP4 inhibition was antagonized by MAP4 (group III antagonist) but not by MCPG or MCCG. Conversely, r-ACPD was antagonized by MCPG but not by (RS)Aminoindan dicarboxylic acid (group I antagonist), MCCG or MSOPPE (group 11 antagonists), or MAP4. Taken together, these results suggest that two pharmacologically distinct presynaptic mGluRs function in an additive fashion to inhibit EPSPs in LC neurons. Because of its specificity lo a limited number of mGluR subtypes and its antagonist profiles, we conclude that L-AP4 acts through mGluR4. The subgroup of mGluR activated by r-ACPD could not be fully resolved using the pharmacological tools currently available, but is distinct from that activated by L-AP4, and its action was not mimicked by the group I mGluR agonist DHPG. Supported by MRC Canada.
LOCALIZATION, CHROMOSOMAL AND DISTRIBUTION: A PROGRESS
ON
THE
EXCITOTOXIC
R.M. Duvoisin, A. Francesconi, A.A. Hirano, N. Min. S. Scherer*, and C. Zhang. Margaret M. Dyson Vision Research Institute, Cornell University Medical College, New York, NY, USA. and *Department of Genetics, Hospital for !3ick Children, Toronto, Canada. Eight metabotropic gltamate receptors hve been cloned to date. the most recent being mGluR8. Using somatic cell hybrd and fluorescence n situ hybridization. the human gene was localized to chromosome position 7q3 1.3-q32.1. Interestingly. the Smith-LemliOpitz syndrome has been mapped to this locus. We have also isolated the mouse mGluR8 gene and proceeded to generate mGluR8 defective transgenic mice by homologous recombina&m in ES cells. To determine the anatomical distribution of mGluR8 in fhe rodent brainm we did in stu hybridization studies and raised a polyclonal antibody against a bacteria1 fusion protein. Comparisons behveen the distribution of the mGluR8 message and protein suggests a presynaptic lo&i&on for mGluR8. This would indicate that the mGluR4, mGluR7 and mGluR8 group III receptors would all be presynnptic receptors and that mGluR6 would be distinct in its very strictly controlled localization to dendrites. Together, these studies should further our understanding of the functional roles of mGluR8. (Supported by National Institute of Health Research to prevent Blindness, Rudin Foundation, New York Academy of Medicine and Canadian Genome Analysis and Technology Program).
All
ROLE
OF
mGluR1
NEURONAL
IN
ACUTE
DEGENERATION
F. Ferraguti, C. Corti, C. Chiamulera. E. Valcrio, S. Costa, *F. Conquet and C. Pietra; GlasoWellcome S.p.A. Medicines Research Centre. Verona. Italy. *Gla..oWellcomc Research & Development S. A., Geneva, Switzerland A role for phosphoinositide (PI) hydrolysis-linked mGluRs (mGluR1 and mGluR5) in the etiology of neurodegenerative conditions involving glutamate escitotosicity has been long debated. Their physiological activation triggers PI hydrolysis, mobilization of intracellular calcium and protein kinase C activation. Excessive stimulation of these mGluRs has been postulated as having neurotosic consequences. Transient global &hernia leads to a dramatic enhancement of mGluR-stimulated PI hydrolysis confined to wlnerable brain regions. On the contra?, evidence obtained on neurons in vitro suggest a regulation of neuronal maturation, plasticity or cell survival b> these receptors. We have previously shown that administration of trans-ACPD in a rodent model of focal ischemia reduced the infarct volume. In the present study, we have further evaluated the influence of mGluRs on acute models of excitotoxicity such as permanent focal ischemia or central administration of the neurotosin kainate in mGluR1 mutant mice. This group of animals demonstrated an increase of infarct volume compared to wild bpe. Kainic acid, icv injected, produced a more severe neurodegeneration in the hippocamus but not in the cerebral cortex of mGluR1 mutant mice compared to wild type animals. These results suggest a dual role for PI-linked mGluRs in conditions: mGlnR1 with neurodegenerative associated throphidreparative phenomena whereas mGluR5 linked to the neurotosic consequences proposed for this class of receptors.
42
ASYMMETRIC SYNTHESIS OF LY354740: A HIGHLY POTENT AND SELECTIVE GROUP 2 mGluR AGONIST CarmenDomfnguez*L. Jestis Ezquerra’. Modesta Espada*, Carmen Pedrega12. Lourdes P&d. 1 Centro de Investigaci6n Lilly S.A. Paraje de la Cruz s/n. 28130Valdeolmos. Madrid. Spain. 2 Departamento de Quimica Organica y Farmacnitica. Fact&ad de Farmacia. Universidad Complutense. 28040-Madrid. Spain.
PRESYNAPTIC
The amino diacid (t)-2.aminobicyclo[3.l,O]hexane-2,6dicarboxylate, LY314582. is a highly potent and selective group 2 metabotropic glutamate receptor agonist. The group 2 mGluR agonist activity of LY314582 has been found to reside in the (+) enamiomer, LY354740. obtained by classical resolution methodologies. We report here an asymmetric synthesis of LY354740. The key intermediate is Ihe cyclopentenone 1. obtained from the commercially available sugar lactone D(+)-ribonic lactonel. From this work, the absolute stereochemistry of LY354740 has been established as lS, 2S, 5R. 6s.
D(+)-Ribonic lactone
1
LY 354740
1 Borcherding, D.R.. Scholtz. S.A., Borchard. R.T. J.Org.Chem. 52, 5457 (1987).
OF EPSPs IN LOCUS
44
43 mGluR8 FUNCTION REl’ORT
INHIBITION
COERULEUS BY MULTIPLE mGluRs G. R. Dub& and KC. Marshall Dept. of Physiology. University of Ottawa, Ottawa, Canada. Activation of metabotropic glutamate receptors (mGluRs) by L-AP4 or r-ACPD (EC,s of 0.92 and 9.2 pM respectively) resulted in an inhibition of excitatory postsynaptic potentials (EPSPs) in intracellularly recorded locus coeruleus (LC) neurons in brain slice preparations (Dub& and Marshall, 1995, Sot. Neurosci. Abstr.). This inhibition was not observed with the potent and specific group I mGluR agonist DHPG (100 ILM). Several additional tests have been made to characterize the locus of action and the mGluR subtype(s) involved in this inhibition. Combined application of LAP4 (10 @f) and r-ACPD (30 pM), caused a significantly greater inhibition than that observed with either one alone. Both agonists produced an increase in paired-pulse facilitation, and failed lo change the LC response to focally applied glutamate, indicating a presynaptic locus of action. The L-AP4 inhibition was antagonized by MAP4 (group III antagonist) but not by MCPG or MCCG. Conversely, r-ACPD was antagonized by MCPG but not by (RS)Aminoindan dicarboxylic acid (group I antagonist), MCCG or MSOPPE (group 11 antagonists), or MAP4. Taken together, these results suggest that two pharmacologically distinct presynaptic mGluRs function in an additive fashion to inhibit EPSPs in LC neurons. Because of its specificity lo a limited number of mGluR subtypes and its antagonist profiles, we conclude that L-AP4 acts through mGluR4. The subgroup of mGluR activated by r-ACPD could not be fully resolved using the pharmacological tools currently available, but is distinct from that activated by L-AP4, and its action was not mimicked by the group I mGluR agonist DHPG. Supported by MRC Canada.
LOCALIZATION, CHROMOSOMAL AND DISTRIBUTION: A PROGRESS
ON
THE
EXCITOTOXIC
R.M. Duvoisin, A. Francesconi, A.A. Hirano, N. Min. S. Scherer*, and C. Zhang. Margaret M. Dyson Vision Research Institute, Cornell University Medical College, New York, NY, USA. and *Department of Genetics, Hospital for !3ick Children, Toronto, Canada. Eight metabotropic gltamate receptors hve been cloned to date. the most recent being mGluR8. Using somatic cell hybrd and fluorescence n situ hybridization. the human gene was localized to chromosome position 7q3 1.3-q32.1. Interestingly. the Smith-LemliOpitz syndrome has been mapped to this locus. We have also isolated the mouse mGluR8 gene and proceeded to generate mGluR8 defective transgenic mice by homologous recombina&m in ES cells. To determine the anatomical distribution of mGluR8 in fhe rodent brainm we did in stu hybridization studies and raised a polyclonal antibody against a bacteria1 fusion protein. Comparisons behveen the distribution of the mGluR8 message and protein suggests a presynaptic lo&i&on for mGluR8. This would indicate that the mGluR4, mGluR7 and mGluR8 group III receptors would all be presynnptic receptors and that mGluR6 would be distinct in its very strictly controlled localization to dendrites. Together, these studies should further our understanding of the functional roles of mGluR8. (Supported by National Institute of Health Research to prevent Blindness, Rudin Foundation, New York Academy of Medicine and Canadian Genome Analysis and Technology Program).
All
ROLE
OF
mGluR1
NEURONAL
IN
ACUTE
DEGENERATION
F. Ferraguti, C. Corti, C. Chiamulera. E. Valcrio, S. Costa, *F. Conquet and C. Pietra; GlasoWellcome S.p.A. Medicines Research Centre. Verona. Italy. *Gla..oWellcomc Research & Development S. A., Geneva, Switzerland A role for phosphoinositide (PI) hydrolysis-linked mGluRs (mGluR1 and mGluR5) in the etiology of neurodegenerative conditions involving glutamate escitotosicity has been long debated. Their physiological activation triggers PI hydrolysis, mobilization of intracellular calcium and protein kinase C activation. Excessive stimulation of these mGluRs has been postulated as having neurotosic consequences. Transient global &hernia leads to a dramatic enhancement of mGluR-stimulated PI hydrolysis confined to wlnerable brain regions. On the contra?, evidence obtained on neurons in vitro suggest a regulation of neuronal maturation, plasticity or cell survival b> these receptors. We have previously shown that administration of trans-ACPD in a rodent model of focal ischemia reduced the infarct volume. In the present study, we have further evaluated the influence of mGluRs on acute models of excitotoxicity such as permanent focal ischemia or central administration of the neurotosin kainate in mGluR1 mutant mice. This group of animals demonstrated an increase of infarct volume compared to wild bpe. Kainic acid, icv injected, produced a more severe neurodegeneration in the hippocamus but not in the cerebral cortex of mGluR1 mutant mice compared to wild type animals. These results suggest a dual role for PI-linked mGluRs in conditions: mGlnR1 with neurodegenerative associated throphidreparative phenomena whereas mGluR5 linked to the neurotosic consequences proposed for this class of receptors.