Studies on the subsynaptosomal localization of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone in the rat hypothalamus

C. R. Parker, W. B. Neaves, A. Barnea, J. C. Porter

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Abstract

In the current investigation, subcellular particles (synaptosomes) of hypothalamic homogenates were isolated by differential centrifugation and discontinuous sucrose density gradient fractionation and found to be rich in LHRH, TRH, and the neuronal marker, norepinephrine (NE). Of the total quantity of LHRH, TRH, or NE in the nuclei-free homogenate, 52-65% was recovered in synaptosomes, whereas the cytosol, myelin/microsomes, and mitochondria contained only 1-12%. To determine the subsynaptosomal localization of LHRH and TRH, purified synaptosomes were lysed and the resulting suspensions were fractionated on discontinuous sucrose density gradients. LHRH (30-40%) was found to be localized primarily in subsynaptosomal particles which banded at sucrose densities between 0.6-1.0 M. Electron microscopic analysis of these particles revealed the presence of dense-cored granules (70-80 nm diameter) and synaptosomal membrane remnants. Norepinephrine was found in two pools within the isolated nerve endings: 15-25% of synaptosomal NE was associated with the synaptic vesicles (45-55-nm diameter); about 40% was in the cytosol. TRH was present primarily as a soluble component of the nerve ending. No apparent association of TRH with densecored granules was demonstrable in this study; however, there may be some TRH in synaptic vesicles.

Original languageEnglish (US)
Pages (from-to)1167-1175
Number of pages9
JournalEndocrinology
Volume102
Issue number4
StatePublished - 1978

Fingerprint

Thyrotropin-Releasing Hormone
Gonadotropin-Releasing Hormone
Hypothalamus
Synaptosomes
Norepinephrine
Sucrose
Nerve Endings
Synaptic Vesicles
Cytosol
Myelin Sheath
Microsomes
Centrifugation
Suspensions
Mitochondria
Electrons
Membranes

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Studies on the subsynaptosomal localization of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone in the rat hypothalamus. / Parker, C. R.; Neaves, W. B.; Barnea, A.; Porter, J. C.

In: Endocrinology, Vol. 102, No. 4, 1978, p. 1167-1175.

Research output: Contribution to journalArticle

Parker, C. R. ; Neaves, W. B. ; Barnea, A. ; Porter, J. C. / Studies on the subsynaptosomal localization of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone in the rat hypothalamus. In: Endocrinology. 1978 ; Vol. 102, No. 4. pp. 1167-1175.
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