Effects of 5, 7-dihydroxytryptamine on serotonin1 and serotonin2 receptors throughout the rat central nervous system using quantitative autoradiography

doi:10.1016/0006-8993(87)91296-0

Brain Research

Volume 421, Issues 1–2, 22 September 1987, Pages 263-279

https://doi.org/10.1016/0006-8993(87)91296-0 Get rights and content

Abstract

The effects of the serotonin neurotoxin 5, 7-dihydroxytryptamine (5, 7-DHT), on serotonin₁ (5-HT₁) and 5-HT₂ receptors were investigated using the high degree of resolution provided by quantitative autoradiography in an effort to determine the synaptic location of these receptors 5, 7-DHT treatment resulted in a decrease in 5-HT₁ binding in the dentate gyrus and CA_3c/4 of the anterior hippocampus and in the dorsal raphe nucleus, whereas no changes were observed in the posterior hippocampus nor in many other brain structures. 5-HT₂ receptors exhibited no changes in any brain area examined in response to 5, 7-DHT treatment, despite over 90% serotonin depletion in most of the forebrain nuclei examined. The results indicate that at least some of the 5-HT₁ sites labelled by [³H]5-HT in the hippocampus and dorsal raphe nucleus are presynaptic, whereas 5-HT₂ receptors are probably postsynaptic. In addition, the distribution profiles of 5-HT₁ and 5-HT₂ binding sites were compared in the rat central nervous system at various anatomical levels. 5-HT₁ binding sites were identified using [³H]5-HT, while 5-HT₂ binding sites were labelled with [³H]ketanserin. Both receptor subtypes displayed distinctly different localization patterns, which, in most cases was the inverse of the other pattern. In the brainstem it is significant that 5-HT₂ receptors are concentrated in the facial nucleus and the motor nucleus of the trigeminal nerve, areas known to influence head and facial movement. The serotonin-mediated head-shake response occurs when 5-HT₂ receptors are activated. In contrast, 5-HT₁ receptors are distributed throughout the brainstem and in specific portions of the spinal cord. These areas are thought to control the serotonin behavioral syndrome and this behavior is 5-HT_1A-mediated. All raphe nuclei were devoid of 5-HT₂ receptors; only 5-HT₁ receptor were found in these nuclei. Correlations with serotonin terminal distribution patterns are discussed. The pattern of 5-HT₂ receptor distribution was also compared with the pattern of α₁ receptors, using [³H]prazosin in order to determine whether [³H]ketanserin significantly labels α₁ receptors. Although some similarities exist, overlap of binding did not occur in other nuclei, indicating that α₁ contamination of this system is probably negligible.

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Effects of 5, 7-dihydroxytryptamine on serotonin1 and serotonin2 receptors throughout the rat central nervous system using quantitative autoradiography

Abstract

Neuropharmacology

Brain Research

Life Sci.

Eur. J. Pharmacol.

TINS

Life Sci.

Life Sci.

Brain Research

TINS

TINS

TINS

Brain Research

Life Sci.

Brain Research

Brain Research

Eur. J. Pharmacol.

Brain Research

Brain Research

Eur. J. Pharmacol.

Neurosci. Lett.

Life Sci.

TINS

Eur. J. Pharmacol.

Effects of 5, 7-dihydroxytryptamine on serotonin₁ and serotonin₂ receptors throughout the rat central nervous system using quantitative autoradiography