Role of the amygdala and periaqueductal gray in anxiety and panic

doi:10.1016/0166-4328(93)90097-A

Behavioural Brain Research

Volume 58, Issues 1–2, 20 December 1993, Pages 123-131

https://doi.org/10.1016/0166-4328(93)90097-A Get rights and content

Abstract

The amygdala (AM) and the periaqueductal gray (PAG) represent the rostral and the caudal pole, respectively, of a longitudinally organized neural system, that is responsible for the integration of behavioral and physiological manifestations of defensive reactions against innate and learned threats. Microinjection of benzodiazepine (BDZ) anxiolytics, GABA^A receptor agonists or 5-HT receptor antagonists into the AM has anxiolytic effects in conflict tests and other models of conditioned fear, while similar administration of 5-HT or of a 5-HT_1A receptor agonist has anxiogenic effects. On the other hand, in the test of electrical stimulation of the PAG, microinjection of 5-HT, 5-HT mimetics, or of drugs that enhance the action of endogenous 5-HT into the same brain area has an antiaversive effect, like BDZ and GABA_A agonists. Furthermore, microinjection of midazolam, of the NMDA receptor antagonist AP-7, or of the $5- HT_{1A1B}$ receptor blocker propranolol increased the exploration of the open arms of the elevated plus-maze, having therefore an anxiolytic effect. These results point to an inhibitory role of the GABA-BDZ system in both the AM and the PAG. In contrast, 5-HT seemingly enhances conditioned fear in the AM, while inhibiting unconditioned fear in the PAG. Thus, $5- HT_{21C}$ antagonists reportedly release punished behavior when injected into the AM, whereas they antagonized the antiaversive effect of 5-HT, zimelidine and $5- HT_{1A1B}$ receptor blockers in the PAG. Since reported clinical studies revealed that one of such compounds, ritanserin, relieves generalized anxiety but tends to aggravate panic disorder, a relationship may be established between the AM and anxiety and the PAG and panic.

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Brain rostro-caudal interactions in memory and emotionRole of the amygdala and periaqueductal gray in anxiety and panic

Abstract

Eur. J. Pharmacol.

Eur. J. Pharmacol.

J. Psychiatry

Brain Res.

Prog. Neuro Psychopharmacol. Biol. Psychiatry

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Eur. J. Pharmacol.

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Pharmacol. Biochem. Behav.

J. Neurosci. Meth.

Neurosci. Lett.

Eur. J. Pharmacol.

Pharmacol. Biochem. Behav.

Behav. Brain Res.

Brain Res.

Brain Res.

Mediation by serotonin of the antiaversive effect of zimelidine and propranolol injected into the dorsal midbrain central grey

J. Psycopharmacol.

Microinjection of propranolol into the dorsal periaqueductal gray causes an anxiolytic effect in the elevated plus-maze antagonized by ritanserin

Psychopharmacology

The serotonin-producing neurons of the midbrain median and dorsal raphe nuclei

Attenuation of chemically induced defence response by 5-HT1 receptor agonists administered into the periaqueductal gray

Psychopharmacology

A perceptual defensive-recuperative model of fear and pain

Behav. Brain Res.

Expression of c-fos protein as a marker for neuronal activity following noxious stimulation in the rat

J. Comp. Neurol.

The influence of ritanserin, a serotonin antagonist in anxiety disorders: a double-blind placebo-controlled study versus lorazepam

Pharmacopsychiatry

5-HT and mechanisms of defence

J. Psychopharmacol.

Serotonin function in panic disorder: a double blind placebo controlled study with fluvoxamine and ritanserin

Psychopharmacology

Identity of inhibitory presynaptic 5-hydroxytryptamine (5-HT) auto-receptors in the rat brain cortex with 5-HT1B binding sites

Naunyn Schmiedeberg's Arch. Pharmacol.

The midbrain periaqueductal gray as a coordinator of action in response to fear and anxiety

Adjunctive buspirone in benzodiazepine treatment of four patients with panic disorder

Am. J. Psychiatry

Brain rostro-caudal interactions in memory and emotion
Role of the amygdala and periaqueductal gray in anxiety and panic

Attenuation of chemically induced defence response by 5-HT₁ receptor agonists administered into the periaqueductal gray

Identity of inhibitory presynaptic 5-hydroxytryptamine (5-HT) auto-receptors in the rat brain cortex with 5-HT_1B binding sites