Effect of FMRFamide on voltage-dependent currents in identified centrifugal neurons of the optic lobe of the cuttlefish, Sepia officinalis

Abstract Whole-cell patch-clamp recordings from identified centrifugal neurons of the optic lobe in a slice preparation allowed the characterization of five voltage-dependent currents; two outward and three inward currents. The outward currents were; the 4-aminopyridine-sensitive transient potassium...

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Bibliographic Details
Published inbioRxiv
Main Author Chrachri, Abdesslam
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 01.10.2020
Subjects
Ammonium
Barium
Brain slice preparation
Cadmium
Calcium channels (L-type)
Calcium channels (T-type)
Calcium channels (voltage-gated)
Calcium currents
Cobalt
Dihydropyridine
FMRFamide
Information processing
Neurons
Neuropeptides
Nifedipine
Optic lobe
Tetrodotoxin
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Summary:Abstract Whole-cell patch-clamp recordings from identified centrifugal neurons of the optic lobe in a slice preparation allowed the characterization of five voltage-dependent currents; two outward and three inward currents. The outward currents were; the 4-aminopyridine-sensitive transient potassium or A-current (IA), the TEA-sensitive sustained current or delayed rectifier (IK). The inward currents were; the tetrodotoxin-sensitive transient current or sodium current (INa). The second is the cobalt- and cadmium-sensitive sustained current which is enhanced by barium and blocked by the dihydropyridine antagonist, nifedipine suggesting that it could be the L-type calcium current (ICaL). Finally, another transient inward current, also carried by calcium, but unlike the L-type, this current is activated at more negative potentials and resembles the low-voltage-activated or T-type calcium current (ICaT) of other preparations. Application of the neuropeptide FMRFamide caused a significant attenuation to the peak amplitude of both sodium and sustained calcium currents without any apparent effect on the transient calcium current. Furthermore, FMRFamide also caused a reduction of both outward currents in these centrifugal neurons. The fact that FMRFamide reduced the magnitude of four of five characterized currents could suggest that this neuropeptide may act as a strong inhibitory agent on these neurons. Summary FMRFamide modulate the ionic currents in identified centrifugal neurons in the optic lobe of cuttlefish: thus, FMRFamide could play a key role in visual processing of these animals. * List of symbols and abbreviations o.gr. outer granule cell layer i.gr. inner granule cell layer pl plexiform zone 4AP 4-aminopryridine TEA tetra-ethyl ammonium TTX tetrodotoxin
DOI:10.1101/2020.09.29.318691