title: Enhanced brain cell proliferation following early adrenalectomy in rats.
abstract: We have previously demonstrated an increase in adult brain DNA content in rats adrenalectomized on postnatal day 11. The present studies examined cell proliferation in cerebral cortex, cerebellum, hippocampus, and midbrain-diencephalon following adrenalectomy at this age. Compared to sham-operated controls, adrenalectomized animals showed increased [3H]thymidine incorporation into DNA (measured at 1 h following a pulse injection) in all brain regions at 7 and 14 days postsurgery. In some areas, the effect was already present as early as 2 days following adrenalectomy. Chronic replacement with corticosterone prevented this increase in DNA labelling in a dose-dependent manner. When cell proliferation in the cerebral cortex and cerebellum was independently assessed by measuring changes in thymidine kinase activity, enzyme activity was significantly elevated in both areas at 7 and 14 days postsurgery. Finally, histological examination of the cerebellar cortex suggested a delayed disappearance of the external granular layer in several cerebellar lobules of adrenalectomized animals. Overall, these findings indicate that day-11 adrenalectomy leads to a prolonged stimulation of mitotic activity in areas where cell formation at this time is exclusively glial (i.e., cerebral cortex and mid-brain-diencephalon) as well as in areas where postnatal neurogenesis is also occurring (cerebellum and hippocampus). It is hypothesized that this stimulation results from the removal of a tonic inhibitory effect exerted by circulating glucocorticoids in the normal intact animal.
authors.affiliation: Department of Psychology, University of Massachusetts, Amherst 01003.
authors.forename: R
authors.initials: R
authors.lastname: Yehuda
authors.forename: K R
authors.initials: KR
authors.lastname: Fairman
authors.forename: J S
authors.initials: JS
authors.lastname: Meyer
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001921:Brain / Q000166:cytology* / Q000201:enzymology; D002455:Cell Division; D003345:Corticosterone / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D005260:Female; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013936:Thymidine / Q000378:metabolism; D013937:Thymidine Kinase / Q000378:metabolism; D013997:Time Factors
chemical_list: D004247:DNA; D013937:Thymidine Kinase; D013936:Thymidine; D003345:Corticosterone