TY - JOUR
T1 - Studies on the subsynaptosomal localization of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone in the rat hypothalamus
AU - Parker, C. R.
AU - Neaves, W. B.
AU - Barnea, A.
AU - Porter, J. C.
PY - 1978/4
Y1 - 1978/4
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0018150648&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0018150648&partnerID=8YFLogxK
U2 - 10.1210/endo-102-4-1167
DO - 10.1210/endo-102-4-1167
M3 - Article
C2 - 105875
AN - SCOPUS:0018150648
SN - 0013-7227
VL - 102
SP - 1167
EP - 1175
JO - Endocrinology
JF - Endocrinology
IS - 4
ER -