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Influence of dopamine receptor agonists and antagonists on calmodulin content in different brain regions
9th Meeting of the ESN
Dlh
62
hl
VULYERABILITY TO BT@WS &MD IN VIVO HIPPOCIWPAL
NOREPINBPNRI#E
RELEASE
F. Petty, G.L. Kramer and Y. Chae Veterans Affairs Medical Center and UT Southwestern Medical School, Dallas, Texas. U.S.A. Learned Helplessness (LH) is a from maladaptive behavior resulting inescapable stress. A norepinephrine (NE) deficit has been postulated in LH for over 10 years. A consistent finding in LH research been variability in has We have susceptibility to stress. developed stable LH and non-LH behavior by restressing rats 1 week and retesting after initial stress exposure. Rats were then implanted with microdialysis probes NE release was in hippocampal (HPC). measured during re-exposure to mild brief stress not sufficient to cause LH in naive animals. Rats with non-LH behavior did not differ from control NE release during mild stress, while rats with demonstrated LH had a significant increase in HPC NE These results release during mild stress. support a central role for HPC NE in LH, coping and suggest that prior poor sensitizes this system. 63
INFLUENCE OF OOPqMINE RECEPTOR AGONISTS AND ANTAGONXSTS ON CAL?@OULXN CONTENT IN DIFFERENT BRAIN REGIONS. N.S.Popov Institute of Pharmacology cology, Medical Academy, Germany
and ToxiMagdeburg,
After single ip.-applicetion of apomorphine and amphetamine to rats, an increase in cytoeolic and reduction in membrane-bound calmodulin was observed in striatua and hippocampus. On the contrary, high-dose amphetamine (5 mg/kg) lowered cytosolic and elevated membrane-bound calmodulin, an effect rather expectAccordingly, in ed for antagonists.
chronic experiments high-dose amphetamine paralleled the effects of heloperidol. Thu5, both substances lowered cytosolic and lncreeeed membrane-bound calmodulin in strletum and hippocaapus. The findings ere discussed in the light that tranemittsrs and interneuronal sigtselling systems participate not only in receptor sensitivity, complex processes
city
but
of
Fn the
neuronal
more
plasti.
as well.
64
EXTEILC~LLULM LWELS OP TAURINE IN THE RAT HIPPOCAMPUSDEPEND ON p3 Puka’ and A.Lehmann2 p*Department of Neurochemistry, Medical Research entre, Warsaw, Poland and !?Institute of Neurobiology, University of Goteborg, Goteborg, Sweden. that studies have shown Microdialysis extracellular taurine increases in response to neural cell swelling. The aim of this study was to assess if swelling induced by perfusion with low pH causes a similar taurine elevation. Microdialysis probes were implanted in the hippocampus of urethaneanesthetized rats. Sampie; were-analyzed for amino acids with HPLC. The perfusion buffer (KrebsRinger bicarbonate-KRB, pH 7.4) was then replaced by KRB with low 6.9 and 6.4 or high (8.4) pH. The effects of the Cl HCO exe ange mblbltor DIDS cian,, Taurine were studied on / ow p &ind!ced was selectively diminished by 35% at * pH 6.9, reduction of taurine (by 50%) and glutamate (by 40%) were observed at pH 6.4. Addition of DIDS to low pH-KRB prevented the drop of taurine. Perfusion with pH 8.4 induced a selective transient enhancement of taurine up to 300%. The results indicate that uptake/release of taurine depends on pH in a DIDS sensitive manner and that release of iaurine is not an universal response to increase in cell volume.
RauschW.-D., Weiser M.
Chen T. S., Reinitzer
D., Koutsilieri E. and
lnstitufe for Medical Chemislfy, Veterinary Medical University, Vienna, Austria.
Neuronal cell cultures form a valuable model to study the acute or long term action of neurotoxins. The follow up of the intracellular Ca2+-concentration and pH by fluorescent techniques are among of the most sensitive indicators of changes in the cellular equilibrium as a response to pathological or toxic conditions. Primary neuronal cell cultures were prepared from embryonic C57/Bl mouse brain at dav 14 of nestation. Cells were grown initially with s&urn analater in a serum free defined medium for 3 weeks. The cultures were characterized by immunohistological techniques for NSE, TH, GFAP. Fura- loaded cells were measured on coverslips or in suspension. Cells were consecutively challenged by extracellular Ca2+concentrations and different-netitoxic compounds as MPTP, MPP+, Daraauat and 6-hvdroxvdoDamine acutely as well asund& incubation ~onditikns: Correlations are attempted to establish morphological (cell count and size, length of processes) as well as biochemical parameters (neurotransmitter content, metabolite concentrations) .
Dlh
62
hl
VULYERABILITY TO BT@WS &MD IN VIVO HIPPOCIWPAL
NOREPINBPNRI#E
RELEASE
F. Petty, G.L. Kramer and Y. Chae Veterans Affairs Medical Center and UT Southwestern Medical School, Dallas, Texas. U.S.A. Learned Helplessness (LH) is a from maladaptive behavior resulting inescapable stress. A norepinephrine (NE) deficit has been postulated in LH for over 10 years. A consistent finding in LH research been variability in has We have susceptibility to stress. developed stable LH and non-LH behavior by restressing rats 1 week and retesting after initial stress exposure. Rats were then implanted with microdialysis probes NE release was in hippocampal (HPC). measured during re-exposure to mild brief stress not sufficient to cause LH in naive animals. Rats with non-LH behavior did not differ from control NE release during mild stress, while rats with demonstrated LH had a significant increase in HPC NE These results release during mild stress. support a central role for HPC NE in LH, coping and suggest that prior poor sensitizes this system. 63
INFLUENCE OF OOPqMINE RECEPTOR AGONISTS AND ANTAGONXSTS ON CAL?@OULXN CONTENT IN DIFFERENT BRAIN REGIONS. N.S.Popov Institute of Pharmacology cology, Medical Academy, Germany
and ToxiMagdeburg,
After single ip.-applicetion of apomorphine and amphetamine to rats, an increase in cytoeolic and reduction in membrane-bound calmodulin was observed in striatua and hippocampus. On the contrary, high-dose amphetamine (5 mg/kg) lowered cytosolic and elevated membrane-bound calmodulin, an effect rather expectAccordingly, in ed for antagonists.
chronic experiments high-dose amphetamine paralleled the effects of heloperidol. Thu5, both substances lowered cytosolic and lncreeeed membrane-bound calmodulin in strletum and hippocaapus. The findings ere discussed in the light that tranemittsrs and interneuronal sigtselling systems participate not only in receptor sensitivity, complex processes
city
but
of
Fn the
neuronal
more
plasti.
as well.
64
EXTEILC~LLULM LWELS OP TAURINE IN THE RAT HIPPOCAMPUSDEPEND ON p3 Puka’ and A.Lehmann2 p*Department of Neurochemistry, Medical Research entre, Warsaw, Poland and !?Institute of Neurobiology, University of Goteborg, Goteborg, Sweden. that studies have shown Microdialysis extracellular taurine increases in response to neural cell swelling. The aim of this study was to assess if swelling induced by perfusion with low pH causes a similar taurine elevation. Microdialysis probes were implanted in the hippocampus of urethaneanesthetized rats. Sampie; were-analyzed for amino acids with HPLC. The perfusion buffer (KrebsRinger bicarbonate-KRB, pH 7.4) was then replaced by KRB with low 6.9 and 6.4 or high (8.4) pH. The effects of the Cl HCO exe ange mblbltor DIDS cian,, Taurine were studied on / ow p &ind!ced was selectively diminished by 35% at * pH 6.9, reduction of taurine (by 50%) and glutamate (by 40%) were observed at pH 6.4. Addition of DIDS to low pH-KRB prevented the drop of taurine. Perfusion with pH 8.4 induced a selective transient enhancement of taurine up to 300%. The results indicate that uptake/release of taurine depends on pH in a DIDS sensitive manner and that release of iaurine is not an universal response to increase in cell volume.
RauschW.-D., Weiser M.
Chen T. S., Reinitzer
D., Koutsilieri E. and
lnstitufe for Medical Chemislfy, Veterinary Medical University, Vienna, Austria.
Neuronal cell cultures form a valuable model to study the acute or long term action of neurotoxins. The follow up of the intracellular Ca2+-concentration and pH by fluorescent techniques are among of the most sensitive indicators of changes in the cellular equilibrium as a response to pathological or toxic conditions. Primary neuronal cell cultures were prepared from embryonic C57/Bl mouse brain at dav 14 of nestation. Cells were grown initially with s&urn analater in a serum free defined medium for 3 weeks. The cultures were characterized by immunohistological techniques for NSE, TH, GFAP. Fura- loaded cells were measured on coverslips or in suspension. Cells were consecutively challenged by extracellular Ca2+concentrations and different-netitoxic compounds as MPTP, MPP+, Daraauat and 6-hvdroxvdoDamine acutely as well asund& incubation ~onditikns: Correlations are attempted to establish morphological (cell count and size, length of processes) as well as biochemical parameters (neurotransmitter content, metabolite concentrations) .