Manipulation of prenatal blood glucocorticoid level affects development ofthe hypothalamic paraventricular nuclei in rats

In order to examine the influence of prenatal alterations of glucocorticoid level on the development of the hypothalamic paraventricular (PVN) and sup raoptic (SON) nuclei, pregnant rats were either injected with dexamethasone (DEX; 1.5 mg/kg/b.w.) or bilaterally adrenalectomized on day 16 of gestati on. Morphometric analysis of neurosecretory cell nuclei was performed on ei ght topographically distinct levels of the PVN and two parts of the SON in 20-day-old fetuses and 3- and 14-day-old neonatal offspring. Significant ch anges were found only in the PVN. Administration of DEX to dams resulted in decreased cell nuclei at level 3 of the PVN, both in fetal and neonatal an imals. On the other hand, removal of maternal adrenals significantly increa sed the size of neurosecretory cell nuclei at levels 5-8 in fetuses, wherea s these changes progressively diminished during the examined postnatal peri od. In the fetuses and 3-day-old pups from adrenalectomized mothers a decre ase of neurosecretory cell nuclei was observed at level 1 and 4. These resu lts demonstrate that prenatal alterations in glucocorticoid level affected different subpopulations of the PVN neurosecretory cells indicating changes in the synthesis of different peptides and/or neurotransmitters. They conf irm and extend the data on the dependence of brain development on prenatal levels of glucocorticoids.