Serotonergic Projections to the Suprachiasmatic Nucleus and the Median Eminence of the Rat: Identification by Fluorescence and Electron Microscope

Overview

Journal J Anat

Specialty Anatomy & Histology

Date 1978 Dec 1

PMID 744749

Citations 2

Authors

K Ajika

J Ochi

Affiliations

Soon will be listed here.

Abstract

The identification of serotonergic input to the rat median eminence and nucleus suprachiasmaticus was carried out by fluorescence and electron microscopy. The clear differentiation of serotonin (5-HT) from catecholamine (CA) neurons was possible with an improved new filter system. 6-hydroxytryptamine (6-HT) was selectively taken up by 5-HT terminals and produced an intense yellow fluorescence. The yellow fluorescence of 5-HT disappeared 2 weeks after treatment with 5,6-dihydroxytryptamine (5,6-DHT), whereas the blue-green fluorescence of CA persisted. Combined treatment with either 6-HT and reserpine with addition to alpha-methyl-p-tyrosine, or with 6-HT and 6-hydroxydopamine, caused a marked reduction of CA and yellow fluorescence prominent only in 5-HT terminals. Under the electron microscope, 6-HT and 5,6-DHT were selectively taken up by the 5-HT terminals and produced electron-dense cores in the small vesicles with a diameter of 50 nm. The quantitative study revealed that the density of serotonin boutons marked with such dense-cored vesicles was 4.3 +/- 0.5% (mean +/- S.E.M.) in the suprachiasmatic nucleus and 4.8 +/- 0.8% in the perivascular region of the median eminence. Several studies have indicated an important functional role of 5-HT in the control of gonadotrophin secretion. The present study suggests that the serotonergic terminals exert their influence on the anterior pituitary function, not only at the level of the suprachiasmatic nucleus, but also at the level of the perivascular region of the median eminence, either through the axo-axonic synapses with the axons containing the releasing hormone or by the direct release of 5-HT into the portal vessels.

Citing Articles

Physiologically relevant changes in serotonin resolved by fast microdialysis.

Yang H, Thompson A, McIntosh B, Altieri S, Andrews A ACS Chem Neurosci. 2013; 4(5):790-8.

PMID: 23614776 PMC: 3656759. DOI: 10.1021/cn400072f.

Circadian variation in sensitivity of suprachiasmatic and lateral geniculate neurones to 5-hydroxytryptamine in the rat.

Mason R J Physiol. 1986; 377:1-13.

PMID: 3795084 PMC: 1182818. DOI: 10.1113/jphysiol.1986.sp016172.

References

OSteen W . SEROTONIN SUPPRESSION OF LUTEINIZATION IN GONADOTROPHIN-TREATED, IMMATURE RATS. Endocrinology. 1964; 74:885-8. DOI: 10.1210/endo-74-6-885. View

Fuxe K . CELLULAR LOCALIZATION OF MONOAMINES IN THE MEDIAN EMINENCE AND THE INFUNDIBULAR STEM OF SOME MAMMALS. Z Zellforsch Mikrosk Anat. 1964; 61:710-24. DOI: 10.1007/BF00342620. View

Ajika K, Hokfelt T . Ultrastructural identification of catecholamine neurones in the hypothalamic periventricular-arcuate nucleus-median eminence complex with special reference to quantitative aspects. Brain Res. 1973; 57(1):97-117. DOI: 10.1016/0006-8993(73)90571-4. View

Barry J, Dubois M, Carette B . Immunofluorescence study of the preoptico-infundibular LRF neurosecretory pathway in the normal, gastrated or testosterone-treated male guinea pig. Endocrinology. 1974; 95(5):1416-23. DOI: 10.1210/endo-95-5-1416. View

LABHSETWAR A . Effects of serotonin on spontaneous ovulation in rats. Nature. 1971; 229(5281):203-4. DOI: 10.1038/229203a0. View

Schneider H, McCANN S . Mono- and indolamines and control of LH secretion. Endocrinology. 1970; 86(5):1127-33. DOI: 10.1210/endo-86-5-1127. View

Jonsson G, Fuxe K, Hokfelt T . On the catecholamine innervation of the hypothalamus, with special reference to the median eminence. Brain Res. 1972; 40(2):271-81. DOI: 10.1016/0006-8993(72)90133-3. View

Kordon C, Glowinski J . Role of hypothalamic monoaminergic neurones in the gonadotrophin release-regulating mechanisms. Neuropharmacology. 1972; 11(2):153-62. DOI: 10.1016/0028-3908(72)90088-3. View

Meyerson B, Carrer H, Eliasson M . 5-Hydroxytryptamine and sexual behavior in the female rat. Adv Biochem Psychopharmacol. 1974; 11(0):229-42. View

10.

Kamberi I . The role of brain monoamines and pineal indoles in the secretion of gonadotrophins and gonadotrophin-releasing factors. Prog Brain Res. 1973; 39:261-80. DOI: 10.1016/S0079-6123(08)64083-2. View

11.

Ochi J, Hosoya Y . Fluorescence microscopic differentiation of monoamines in the hypothalamus and spinal cord of the lamprey, using a new filter system. Histochemistry. 1974; 40(3):263-6. DOI: 10.1007/BF00501961. View

12.

Baumgarten H, Lachenmayer L . Indolemine-containing nerve terminals in the rat median eminence. Z Zellforsch Mikrosk Anat. 1974; 147(2):285-92. DOI: 10.1007/BF00582802. View

13.

Bjorklund A, Nobin A, Stenevi U . Effects of 5,6-dihydroxytryptamine on nerve terminal serotonin and serotonin uptake in the rat brain. Brain Res. 1973; 53(1):117-27. DOI: 10.1016/0006-8993(73)90771-3. View

14.

Bjorklund A, Nobin A . Fluorescence histochemical and microspectrofluorometric mapping of dopamine and noradrenaline cell groups in the rat diencephalon. Brain Res. 1973; 51:193-205. DOI: 10.1016/0006-8993(73)90372-7. View

15.

Baumgarten H, Bjorklund A, HOLSTEIN A, Nobin A . Chemical degeneration of indolamine axons in rat brain by 5,6-dihydroxytryptamine. An ultrastructural study. Z Zellforsch Mikrosk Anat. 1972; 129(2):256-71. DOI: 10.1007/BF00306939. View

16.

Baumgarten H, Lachenmayer L, SCHLOSSBERGER H . Evidence for a degeneration of indoleamine containing nerve terminals in rat brain, induced by 5,6-dihydroxytryptamine. Z Zellforsch Mikrosk Anat. 1972; 125(4):553-69. DOI: 10.1007/BF00306659. View

17.

SETALO G, Vigh S, Schally A, Arimura A, Flerko B . Immunohistological study of the origin of LH-RH-containing nerve fibers of the rat hypothalamus. Brain Res. 1976; 103(3):597-602. DOI: 10.1016/0006-8993(76)90462-5. View

18.

Ajika K, Hokfelt T . Projections to the median eminence and the arcuate nucleus with special reference to monoamine systems: effects of lesions. Cell Tissue Res. 1975; 158(1):15-35. DOI: 10.1007/BF00219949. View

19.

Jonsson G, Sandler M . Fluorescence of indolylethylamines condensed with formaldehyde. Histochemie. 1969; 17(3):207-12. DOI: 10.1007/BF00309865. View

20.

Jonsson G, Fuxe K, Hamberger B, Hokfelt T . 6-hydroxytryptamine--a new tool in monoamine fluorescence histochemistry. Brain Res. 1969; 13(1):190-5. DOI: 10.1016/0006-8993(69)90156-5. View