Expression and conditioned inhibition of fear-potentiated startle after stimulation and blockade of AMPA/Kainate and GABA(A) receptors in the dorsal periaqueductal gray.
Previous work showed that the dorsal periaqueductal gray is involved in the inhibition of fear-potentiated startle. The present study investigated the effects of blockade and stimulation of Kainate/AMPA and GABA(A) receptors within the dorsal periaqueductal gray on expression and conditioned inhibition of fear-potentiated startle. Blockade of the Kainate/AMPA receptors enhanced whereas stimulation of the Kainate/AMPA receptors decreased expression of fear-potentiated startle. These effects do not reflect conditioned inhibition since this modulation was not changed by injections of Kainate/AMPA receptor agonists or antagonists into the dorsal periaqueductal gray. Stimulation and blockade of GABA(A) receptors within the dorsal periaqueductal gray neither affected expression of fear-potentiated startle nor its conditioned inhibition. The present results together with findings from the literature indicate that glutamate in the dorsal periaqueductal gray is a critical substrate for the expression and modulation of fear-related behaviours.
Fendt
M
M
Tierphysiologie, Universität Tübingen, Auf der Morgenstelle 28, D-72076, Tübingen, Germany. markus.fendt@uni-tuebingen.de
D000161:Acoustic Stimulation; D000818:Animals; D003214:Conditioning, Classical; D004597:Electroshock; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D005239:Fear / Q000502:physiology*; D007608:Kainic Acid / Q000008:administration & dosage / Q000494:pharmacology; D008027:Light; D008297:Male; D008845:Microinjections; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D010852:Picrotoxin / Q000494:pharmacology; D010880:Piperidines / Q000008:administration & dosage / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology*; D011963:Receptors, GABA-A / Q000502:physiology*; D018092:Kainic Acid Receptors / Q000502:physiology*; D013216:Reflex, Startle / Q000502:physiology*
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D007608:Kainic Acid; D010852:Picrotoxin; D010880:Piperidines; D011810:Quinoxalines; D018091:Receptors, AMPA; D011963:Receptors, GABA-A; D018092:Kainic Acid Receptors; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; C032727:piperidine