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Increased proliferation of neuroglia and endothelial cells in the supraoptic nucleus and hypophysial neural lobe of young rats drinking hypertonic sodium chloride solution
Author(s) -
Paterson Jean A.,
Leblond C. P.
Publication year - 1977
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.901750402
Subject(s) - supraoptic nucleus , vasopressin , endocrinology , medicine , biology , nucleus , hypertonic saline , astrocyte , neuroglia , hypothalamus , central nervous system , microbiology and biotechnology
Male rats aged 30 to 35 days were provided with 1.75% sodium chloride solution as drinking fluid for two weeks, to create a chronic increase in plasma osmolality. During this time, the animals and a control group of water‐drinking rats received two injections per day of 1 μCi of 3 H‐thymidine per gram body weight to label dividing cells and their progeny. At the end of this period, the animals were sacrificed by aldehyde perfusion. Sections 1 μm‐thick were saved at intervals from a series cut throughout the length of the supraoptic nucleus; these sections and others taken from the caudate nucleus and the neural lobe of the hypophysis were processed for radioautography. Neuronal nuclei and nucleoli were enlarged in the supraoptic nucleus of salttreated rats, in accord with previous work indicative of neuronal enlargement associated with increased protein synthesis and probably enhanced vasopressin production. Furthermore, most axon terminals in the neural lobe were depleted of neurosecretory granules in the salt‐treated group, a fact suggesting increased release of vasopressin. Cell counts in radioautographs of the supraoptic nucleus revealed that 20.6% of the astrocytes were labeled in salt‐treated rats, but only 5.9% in controls, indicating a marked increase in the production of new astrocytes in the treated animals. Also, endothelial cells were more frequently labeled in salt‐treated rats (52.9%) than in controls (17.4%). In the caudate nucleus, by contrast, the labeling percentages of astrocytes or of endothelial cells did not differ between control and treated rats. In the neural lobe, the labelling percentage of pituicytes was 45.8% in treated, but only 3.1% in control animals. The endothelial cell labeling was also greater in treated (46.5%) than controls (23.9%). Thus, in young rats, a period of salt ingestion elicited both an enlargement of supraoptic neurons and an increase in the production of the astrocytes, pituicytes, and endothelial cells associated with these neurons and their processes.