Neither peripheral nerve input nor cortical NMDA receptor activity are necessary for recovery of a disrupted barrel pattern in rat somatosensory cortex.
Elevating cortical serotonin (5-HT) in rats from postnatal day (P-) 0 to P-6 by administering the monoamine oxidase (MAO(A)) inhibitor, clorgyline, produces a dose-dependent spectrum of effects on rat somatosensory organization, ranging from enlarged with indistinct septa to a complete lack of vibrissae-related patterns. However, if clorgyline treatment is stopped on P-6, a qualitatively and quantitatively normal vibrissae-related pattern of thalamocortical afferents appears in somatosensory cortex (S-I) on P-10. We employed high performance liquid chromatography (HPLC), infraorbital nerve (ION) transection, N-methyl-D-aspartate (NMDA) receptor blockade, 1,1'-dioctadecyl-3,3,3"3'-tetramethylindocarbocyanine perchlorate (DiI) labeling of thalamic afferents, and CO histochemistry to determine whether peripheral nerve input and/or cortical NMDA receptor activity were required for the recovery of vibrissae-related patterns in clorgyline-treated animals. Clorgyline administration from P-0 to P-6 produced a 1589.4+/-53.3% increase in cortical 5-HT over control animals on P-6 and a 268.8+/-6.3% elevation over controls at P-10. Postnatal day 6 pups had significantly altered vibrissae-related patterns in S-I following 6 days of clorgyline treatment but by P-10, the characteristic vibrissae-related patterns were restored. Neither transection of the ION nor application of the NMDA antagonist, DL-2-amino-5-phosphonovaleric acid (APV), to the cortices of P-6 pups that were treated with clorgyline from birth had any significant effect on the recovery of the vibrissae-related patterns by P-10. These results indicate that neither peripheral nerve input nor cortical NMDA receptor activity are necessary for the restoration of cortical vibrissae-related patterns in rats that have sustained transient elevations of 5-HT.
Boylan
C B
CB
Department of Anatomy and Neurobiology, Medical College of Ohio, 3035 Arlington Avenue, Toledo, OH 43614-5804, USA. cboylan@mco.edu
Kesterson
K L
KL
Bennett-Clarke
C A
CA
Chiaia
N L
NL
Rhoades
R W
RW
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography; D001933:Brain Stem / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D002232:Carbocyanines; D002851:Chromatography, High Pressure Liquid; D003010:Clorgyline / Q000494:pharmacology; D003714:Denervation; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D005456:Fluorescent Dyes; D007457:Iodine Radioisotopes; D008297:Male; D008442:Maxillary Nerve / Q000166:cytology* / Q000502:physiology*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D009475:Neurons, Afferent / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development*; D013788:Thalamus / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D014738:Vibrissae / Q000294:innervation
C035005:3,3'-dihexadecylindocarbocyanine; D002232:Carbocyanines; D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D007457:Iodine Radioisotopes; D008996:Monoamine Oxidase Inhibitors; D016194:Receptors, N-Methyl-D-Aspartate; D012701:Serotonin; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate; D003010:Clorgyline