Rapid contact call-driven induction of NR2A and NR2B NMDA subunit mRNAs in the auditory thalamus of the budgerigar (Melopsittacus undulatus).
In situ hybridization histochemistry was used to assess the effect of auditory stimulation with natural contact calls on expression of NR2A and NR2B NMDA subunit mRNAs in neurons of the thalamic auditory relay nucleus ovoidalis (Ov) of a vocal learning parrot species, the budgerigar (Melopsittacus undulatus). The results showed that both the core (Ov) and ventromedial shell subdivisions (Ovm) of ovoidalis contained neurons expressing NR2A and NR2B mRNA in no-stimulation control subjects and that the distributions of neurons expressing these subunit mRNAs were very similar in both the core and shell of Ov. Contact call stimulation (5, 30 and 180 min) resulted in substantial increases of 50-60% in the number of neurons expressing NR2A and NR2B mRNAs in both the core and shell. Staining intensity, as measured by the optical density of stained somata approximately doubled compared to controls for both NR2 subunits in the 5 and 30 min conditions, but declined from 30 to 180 min. In all conditions, the density, but not staining intensity, of neurons expressing NR2B exceeded NR2A expression. Furthermore, the density of neurons expressing both subunit mRNAs in call stimulation conditions was greater in the core than in the shell despite the fact that total neuronal density was approximately 20% higher in the shell. Previous experiments have shown that call stimulation is more effective at inducing expression of the immediate early gene zenk in the Ov shell than core; however the present results do not indicate that either NR2A or NR2B mRNA expression mediates this effect since neither subunit exhibits greater expression in Ovm. Ca(++) release is needed for immediate early gene expression, however and, notably, Ovm contains large numbers of neurons containing CGRP, a peptide which has been shown to increase cytosolic Ca(++) levels.
Brauth
Steven E
SE
Department of Psychology, University of Maryland, College Park, MD 20742, USA. brauth@psyc.umd.edu <brauth@psyc.umd.edu>
Liang
Wenru
W
Tang
YeZhong
Y
Galdzicka
Ewa
E
Hall
William S
WS
D000161:Acoustic Stimulation; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D001483:Base Sequence; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D046408:Melopsittacus / Q000378:metabolism*; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D013787:Thalamic Nuclei / Q000166:cytology / Q000378:metabolism*; D014018:Tissue Distribution; D014828:Vocalization, Animal / Q000502:physiology
C120997:NR2A NMDA receptor; C121001:NR2B NMDA receptor; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate