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The effect of oral 5-HTP administration on 5-HTP and 5-HT immunoreactivity in monoaminergic brain regions of rats.
J Chem Neuroanat 2004; 27(2):129-38JC

Abstract

5-Hydroxytryptophan (5-HTP), which is the rate-limiting precursor in serotonin (5-hydroxytryptamine (5-HT)) biosynthesis, is used as an oral supplement to enhance serotonin levels in humans. To evaluate its effects on serotonin levels and localization, 5-hydroxytryptophan was administered to Sprague-Dawley rats either orally or via intraperitoneal injection. 5-Hydroxytryptophan-immunoreactivity was co-localized with serotonin-immunoreactivity in the serotonergic dorsal raphe nucleus of control animals and this was not changed in animals given 5-hydroxytryptophan. Oral 5-HTP administration increased the intensity of both 5-HTP and serotonin immunoreactivity in raphe neurons. However, 5-HTP treatment also caused ectopic 5-hydroxytryptophan-immunoreactivity and serotonin-immunoreactivity in normally dopaminergic neurons of the substantia nigra par compacta. Serotonin-immunoreactivity was confined to neurons that also displayed amino acid decarboxylase immunoreactivity, but in a small percentage of substantia nigra neurons, serotonin immunoreactivity was not co-localized with tyrosine hydroxylase-immunoreactivity. The intensity of the immunoreactivity to serotonin and 5-hydroxytryptophan in the substantia nigra was maximal within 2h of 5-hydroxytryptophan administration and returned to control levels by 24h. This time course mirrored changes in HPLC measurements of 5-hydroxytryptophan, serotonin, and the metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the urine. 5-Hydroxytryptophan administration did not cause ectopic appearance of either serotonin or 5-hydroxytryptophan in the noradrenergic locus coeruleus. These results suggest that a single oral dose of 5-HTP increases the 5-HTP and serotonin content of serotonergic neurons and causes the transient ectopic appearance of serotonin in some normally non-serotonergic neurons.

Authors+Show Affiliations

Department of Biology, MSC 8L0389, Georgia State University, 33 Gilmer St SE Unit 8, Atlanta, GA 30303-3088, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15121217

Citation

Lynn-Bullock, Christina P., et al. "The Effect of Oral 5-HTP Administration On 5-HTP and 5-HT Immunoreactivity in Monoaminergic Brain Regions of Rats." Journal of Chemical Neuroanatomy, vol. 27, no. 2, 2004, pp. 129-38.
Lynn-Bullock CP, Welshhans K, Pallas SL, et al. The effect of oral 5-HTP administration on 5-HTP and 5-HT immunoreactivity in monoaminergic brain regions of rats. J Chem Neuroanat. 2004;27(2):129-38.
Lynn-Bullock, C. P., Welshhans, K., Pallas, S. L., & Katz, P. S. (2004). The effect of oral 5-HTP administration on 5-HTP and 5-HT immunoreactivity in monoaminergic brain regions of rats. Journal of Chemical Neuroanatomy, 27(2), pp. 129-38.
Lynn-Bullock CP, et al. The Effect of Oral 5-HTP Administration On 5-HTP and 5-HT Immunoreactivity in Monoaminergic Brain Regions of Rats. J Chem Neuroanat. 2004;27(2):129-38. PubMed PMID: 15121217.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The effect of oral 5-HTP administration on 5-HTP and 5-HT immunoreactivity in monoaminergic brain regions of rats. AU - Lynn-Bullock,Christina P, AU - Welshhans,Kristy, AU - Pallas,Sarah L, AU - Katz,Paul S, PY - 2003/05/23/received PY - 2003/11/24/revised PY - 2004/02/02/accepted PY - 2004/5/4/pubmed PY - 2004/7/17/medline PY - 2004/5/4/entrez SP - 129 EP - 38 JF - Journal of chemical neuroanatomy JO - J. Chem. Neuroanat. VL - 27 IS - 2 N2 - 5-Hydroxytryptophan (5-HTP), which is the rate-limiting precursor in serotonin (5-hydroxytryptamine (5-HT)) biosynthesis, is used as an oral supplement to enhance serotonin levels in humans. To evaluate its effects on serotonin levels and localization, 5-hydroxytryptophan was administered to Sprague-Dawley rats either orally or via intraperitoneal injection. 5-Hydroxytryptophan-immunoreactivity was co-localized with serotonin-immunoreactivity in the serotonergic dorsal raphe nucleus of control animals and this was not changed in animals given 5-hydroxytryptophan. Oral 5-HTP administration increased the intensity of both 5-HTP and serotonin immunoreactivity in raphe neurons. However, 5-HTP treatment also caused ectopic 5-hydroxytryptophan-immunoreactivity and serotonin-immunoreactivity in normally dopaminergic neurons of the substantia nigra par compacta. Serotonin-immunoreactivity was confined to neurons that also displayed amino acid decarboxylase immunoreactivity, but in a small percentage of substantia nigra neurons, serotonin immunoreactivity was not co-localized with tyrosine hydroxylase-immunoreactivity. The intensity of the immunoreactivity to serotonin and 5-hydroxytryptophan in the substantia nigra was maximal within 2h of 5-hydroxytryptophan administration and returned to control levels by 24h. This time course mirrored changes in HPLC measurements of 5-hydroxytryptophan, serotonin, and the metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the urine. 5-Hydroxytryptophan administration did not cause ectopic appearance of either serotonin or 5-hydroxytryptophan in the noradrenergic locus coeruleus. These results suggest that a single oral dose of 5-HTP increases the 5-HTP and serotonin content of serotonergic neurons and causes the transient ectopic appearance of serotonin in some normally non-serotonergic neurons. SN - 0891-0618 UR - https://www.unboundmedicine.com/medline/citation/15121217/The_effect_of_oral_5_HTP_administration_on_5_HTP_and_5_HT_immunoreactivity_in_monoaminergic_brain_regions_of_rats_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0891061804000274 DB - PRIME DP - Unbound Medicine ER -