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Estradiol‐concentrating forebrain and midbrain neurons project directly to the medulla
Author(s) -
Corodimas Keith P.,
Morrell Joan I.
Publication year - 1990
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902910408
Subject(s) - medulla , stria terminalis , biology , hypothalamus , midbrain , nucleus , central nucleus of the amygdala , forebrain , anatomy , adrenal medulla , extended amygdala , endocrinology , medicine , neuroscience , central nervous system , catecholamine
The location and number of estradiol (E 2 )‐concentrating neurons afferent to the dorsal medulla were determined by combining retrograde fluorescent tract tracing with steroid hormone autoradiography. Injections of Fluoro‐Gold were made into the medulla of 80 day old, ovariectomized, and adrenalectomized female rats. After 7 days survival to allow for retrograde transport, females were injected with [ 3 H] estradiol; they were then perfused and their brains processed for steroid hormone autoradiography. Following a 4hyphen;12 month exposure period, autoradiograms were developed and microscopically analyzed for the presence of E 2 ‐concentrating neurons that project to the medulla. Numerous E 2 ‐concentrating neurons were identified that send axons directly to the medulla; the majority were found in the bed nucleus of the stria terminalis, paraventricular nucleus of the hypothalamus, central nucleus of the amygdala, and the central gray. Of the E 2 ‐concentrating neurons in the bed nucleus of the stria terminalis, 12.7% also projected to the medulla. E 2 ‐concentrating neurons that sent axons to the medulla were also identified in and ventromedial to the lateral parvicellular subdivision in the caudal half of the paraventricular nucleus of the hypothalamus (69.4%). Over one‐third of the E 2 ‐concentrating neurons found in the central nucleus of the amygdala coursed to the medulla. The central gray was the only mesencephalic brain region that contained E 2 ‐concentrating neurons that projected to the medulla (41.9%). The medulla‐bound E 2 ‐concentrating forebrain and midbrain neurons identified in the present study may influence autonomic tone via direct projections.