N-(2-Chloroethyl)-N-ethyl-2-bromobenzylamine reduces intracellular calcium response to noradrenaline in rat visual cortex.
Using the fluorescent indicator Fura-2, we investigated the effects of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), a noradrenergic neurotoxin, on intracellular calcium responses to noradrenaline, N-methyl-D-aspartate, and carbamylcholine chloride in brain slices of the rat visual cortex. Noradrenergic depletion in the visual cortex of young rats was induced by DSP-4, and its selectivity was confirmed by two different methods, i.e., immunostaining with anti-dopamine-beta-hydroxylase antibody and biochemical analysis by high-performance liquid chromatography. The treatment with DSP-4 (25 mg/kg i.p., x2) caused disruption of noradrenergic fibers throughout all cortical layers, and reduced the content of noradrenaline to 6.4% of that in the normal control. In the normal cortex, bath-applied noradrenaline (100 microM) increased the intracellular calcium to 123% of the control in terms of the F(340)/F(380) ratio of Fura-2 fluorescence. Quantitative analysis of the F(340)/F(380) ratio was performed in layers II to IV, since the increase was mainly observed in these layers. The intracellular calcium response to noradrenaline was significantly (P<0.0001) reduced in the DSP-4-treated animals to 63.2% of that in the normal control. The response to N-methyl-D-aspartate (100 microM) was also reduced, whereas the response to carbamylcholine chloride, a muscarinic cholinergic agonist (100 microM), was not affected by the DSP-4 treatment. From these findings we suggest that noradrenergic denervation by DSP-4 reduces the intracellular calcium response to noradrenaline through changes in the intracellular signal transduction.
Yamamoto
M
M
Department of Ophthalmology, Kobe University School of Medicine, Hyogo, Japan.
Imamura
K
K
Kobayashi
M
M
Nakadate
K
K
Yokoyama
C
C
Watanabe
Y
Y
Yamamoto
M
M
Negi
A
A
D018663:Adrenergic Agents / Q000494:pharmacology*; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D015151:Immunoblotting; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D014793:Visual Cortex / Q000187:drug effects* / Q000378:metabolism*
D018663:Adrenergic Agents; D001596:Benzylamines; D018679:Cholinergic Agonists; D018690:Excitatory Amino Acid Agonists; D018340:Receptors, Adrenergic, alpha-1; D002217:Carbachol; C012102:DSP 4; D002118:Calcium; D009638:Norepinephrine