p-Chloroamphetamine treatment modifies evoked responses to sinusoidal gratings in the pigeon optic tectum.
This study was performed in order to establish whether selective depletion of serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the pigeon optic tectum (TeO) induced by p-chloroamphetamine (p-CA) modified tectal evoked potentials (TEPs). TEPs in response to sinusoidal gratings of different contrast, spatial and temporal frequency were recorded in control pigeons and in pigeons intraperitoneally injected with p-CA (10 mg/kg; two administrations in consecutive days). TEPs of p-CA treated pigeons, as compared to those of control pigeons, were reduced in amplitude as a function of contrast, spatial and temporal frequency. In addition, TEPs of p-CA treated pigeons differed from those recorded in controls in their transfer characteristics of contrast and spatial frequency. In particular, TEPs of p-CA treated pigeons did not saturate at moderate contrast, unlike those of controls. Furthermore, the TEP spatial tuning in p-CA treated pigeons is broader than that in controls; it thus suggests a reduction of spatial-frequency selectivity. These findings indicate that a selective neurotoxin for serotonergic systems, such as p-CA, can serve as a useful denervation tool for the study of the serotonergic function in the pigeon TeO. In addition, selective changes of TEP properties suggest the possibility that serotonergic afferents play a modulatory role on the receptive-field characteristics of tectal neurons.
Alesci
R
R
Department of Physiology and Biochemistry, University of Pisa, Italy.
Porciatti
V
V
Sebastiani
L
L
Bagnoli
P
P
D000704:Analysis of Variance; D000818:Animals; D010856:Columbidae / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D012701:Serotonin / Q000378:metabolism; D013477:Superior Colliculi / Q000378:metabolism / Q000502:physiology*; D010133:p-Chloroamphetamine / Q000494:pharmacology*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D010133:p-Chloroamphetamine