Journal of neuroendocrinology
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J. Neuroendocrinol. · Jan 1999
Changes in NADPH-d staining in the paraventricular and supraoptic nuclei during pregnancy and lactation in rats: role of ovarian steroids and oxytocin.
Staining for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), a histochemical marker for nitric oxide synthase (NOS), is increased in the supraoptic (SON) and paraventricular (PVN) nuclei in late pregnant rats. To determine whether increases in staining were evident at other times during pregnancy and lactation the number of cells that stained for NADPH-d in the SON and PVN in rats on days 4, 12, 16, and 22 of pregnancy and on days 4, 12, and 20 of lactation was compared to that in virgin females. In a second experiment the influence of ovarian hormones on NADPH-d staining was assessed by comparing staining in the SON and PVN among ovariectomized animals exposed to either a steroid hormone replacement schedule that mimics late pregnancy (oestrogen and progesterone with progesterone removal), oestrogen alone, oestrogen and progesterone, or cholesterol alone. ⋯ The number of cells showing dense staining for NADPH-d in both the SON and PVN increased on days 12 and 22 of pregnancy and 4 and 12 of lactation compared to that observed in virgins. NADPH-d staining in these areas was also increased by both the steroid treatment that mimicked late pregnancy and chronic central OT infusion in oestrogen-primed animals. These data suggest that NADPH-d staining in the SON and PVN is increased at times when oxytocinergic cells are known to be active and that the hormonal state associated with late pregnancy is sufficient to increase NADPH-d staining.
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J. Neuroendocrinol. · Jan 1999
Differential regulation of hippocampal glucocorticoid receptors mRNA and fast feedback: relevance to post-traumatic stress disorder.
Hippocampal glucocorticoid receptors (GR and MR) play an important role in glucocorticoid negative feedback. Abnormalities in negative feedback are found in depression and in post-traumatic stress disorder (PTSD), suggesting that GR and MR might be involved in the pathophysiology of these disorders. Enhanced negative feedback, the PTSD-specific neuroendocrine abnormality, can be induced in animals using a single prolonged stress (SPS) paradigm (a number of different stressors in one prolonged session, 'no stress' interval and a testing session one week later). ⋯ The MR/GR ratio was decreased only in animals that had enhanced fast feedback. These findings suggest that the increase in GR, in hippocampus is involved in the fast feedback hypersensitivity observed in the SPS animals, and might also underlie enhanced dexamethasone sensitivity found in PTSD. Since differential activation of GR and MR can modulate memory, behavioural responsivity, anxiety and fear, change in MR/GR ratio might also explain other PTSD-related phenomena.