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Accumulation of Thyrotropin Releasing Hormone by Rat Hypothalamic Slices
Author(s) -
Charli JeanLouis,
Ponce Georgina,
McKelvy Jeffrey F.,
JosephBravo Patricia
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb12700.x
Subject(s) - thyrotropin releasing hormone , medicine , endocrinology , chemistry , hypothalamus , ouabain , dinitrophenol , hormone , extracellular , incubation , neurotransmission , biology , biochemistry , receptor , sodium , organic chemistry
It has been postulated that thyrotropin releasing hormone (TRH) may play an active role in synaptic transmission. If such is the case, an inactivation mechanism must exist, in analogy to other neuroactive substances. In these studies we have considered the possibility that TRH may be taken up by rat hypothalamic slices. We observed that in the presence of bacitracin TRH was stable in the medium up to 90 min. We detected intact [ 3 H]Pro‐TRH associated with the slices as evidenced by TLC and paper electrophoresis; the association was time‐dependent up to 60 min, and the maximum tissue‐to‐medium ratio was 1.3 at this time. At 5 min incubation, 30‐50% of the TRH was not extracellular, and the plot of TRH‐associated tissue versus the total amount of tissue was linear up to two hypothalami per flask. The association was saturable (K m 1.07 μM) and temperature‐dependent, and the saturable part of the accumulation was inhibited by ouabain, dinitrophenol, and the absence of glucose. These results suggest that an uptake mechanism for TRH exists in the hypothalamus; its physiological relevance remains to be elucidated.