Atrial Natriuretic Factor Concentrations in Discrete Brain Regions, Pituitary, Cardiac Atria and Plasma during the Estrous Cycle in Rats

Hoffman, Neil W.; MacPhee, Allan A.; Gerall, Arnold A.

doi:10.1159/000125715

Cited by 5 publications

(5 citation statements)

References 21 publications

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“…Both oestrogen and progesterone have renal actions of their own, progesterone in¬ creasing sodium excretion by acting as an antagonist of aldosterone (Rafestin-Oblin et al 1991) and oestrogen having aldosterone-like effects (De Vries et al 1972). Also, ovarian steroids may be responsible for cyclical variations in the release of other hormones such as atrial natriuretic peptide, aldosterone and oxytocin which are involved in fluid balance (Hoffman et al 1991, Oelkers et al 1991, Windle & Forsling 1993). Therefore the observations recorded here may represent the separate renal actions of these hormones.…”

Section: Discussionmentioning

confidence: 99%

The natriuretic actions of vasopressin in the female rat: variations during the 4 days of the oestrous cycle

Forsling

Zhou²,

Windle³

1996

Journal of Endocrinology

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The renal actions of vasopressin were studied in the conscious female rat. Vasopressin caused a dose-dependent increase in sodium excretion when administered at 40-160 pmol/min. The highest dose, which increased sodium excretion from 10.4 +/- 0.3 mumol/min (n = 32) to 18.3 +/- 0.8 mumol/min (n = 8, P < 0.001), also caused a significant rise in glomerular filtration rate (GFR). The antidiuretic and natriuretic responses to vasopressin varied significantly over the 4 days of the oestrous cycle. Both responses were greatest on pro-oestrus, being -57 +/- 3 and 52 +/- 3% above the control values with 80 pmol vasopressin/min. Responses of similar magnitude were also seen on dioestrus day 1. On these two cycle days the effects on urine flow and sodium excretion were accompanied by a significant increase in GFR. Smaller antidiuretic and natriuretic responses were seen on oestrus and dioestrus day 2, without concomitant changes in GFR. As the plasma vasopressin concentrations produced by hormone infusion were similar on each day of the cycle, the renal responsiveness to vasopressin appears to vary over the 4 days of the oestrous cycle. This may be important in terms of alteration and possible disturbances of fluid balance which may occur during reproductive cycles and pregnancy.

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Section: Discussionmentioning

confidence: 99%

The natriuretic actions of vasopressin in the female rat: variations during the 4 days of the oestrous cycle

Forsling

Zhou²,

Windle³

1996

Journal of Endocrinology

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“…Similarly, rats were least responsive to oxytocin during dioestrus days 1 and 2 when basal excretion rates were high and low respectively. The cyclical variations in basal excretion rates may result from variations in the release of other renally active hormones over the ovarian cycle -for example, vasopressin (Forsling & Peysner 1988), atrial natriuretic peptide (Hoffman et al 1991), or aldosterone (Braley et al 1996). As the plasma concentrations of oxytocin produced by hormone infusion were comparable between the different days of the cycle, the variations in the responses seen are likely to reflect altered renal responsiveness to the hormone rather than variable rates of hormone clearance.…”

Section: Discussionmentioning

confidence: 99%

“…The plasma concentrations of oxytocin vary over the rat's oestrous cycle (Windle & Forsling 1993), together with the concentrations of a number of other potentially natriuretic peptides -including vasopressin (Forsling & Peysner 1988) and atrial natriuretic peptide (Hoffman et al 1991). The disparity between the circulating hormone concentrations and the small cyclical variations in sodium balance reported in the female rat (Forsling & Peysner 1988) suggest that changes in renal responsiveness may help to maintain sodium homeostasis over the 4 days of the oestrous cycle.…”

Section: Introductionmentioning

confidence: 99%

Renal responses to oxytocin during the 4 days of the oestrous cycle in the rat

Windle

Forsling²

1997

Journal of Endocrinology

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Oxytocin was administered to virgin female rats at doses of 25-200 pmol/min during 0.077 mol NaCl/l infusion at 150 microliters/min on each day of the oestrous cycle. The resultant rates of urine flow, glomerular filtration (GFR) and electrolyte excretion were determined. Oxytocin caused significant increases in urine flow (P < 0.001) and sodium excretion (P < 0.001); both responses being dose-dependent (P < 0.02 and P < 0.01 respectively). Significant variations in the renal responsiveness to the hormone occurred over the 4 days of the oestrous cycle. On oestrus the lowest dose of 25 pmol oxytocin/min produced a significant increase in urine flow (from 139.5 +/- 4.3 to 165.6 +/- 7.1 microliters/min, P < 0.005) and a dose of 50 pmol/min produced a significant increase in sodium excretion (from 10.6 +/- 0.1 to 14.5 +/- 0.7 mumol/min, P < 0.005). Significant increases in urine flow and sodium excretion were seen on pro-oestrus with hormone administration rates of 50 and 100 pmol/min respectively and on dioestrus day 2 with a rate of 100 pmol/min. On dioestrus day 1 no increase in urine flow or sodium excretion was seen over the dose range of oxytocin administration. A dose of 100 pmol oxytocin/min significantly increased GFR on pro-oestrus and dioestrus day 2, but not on the other 2 days of the cycle. The circulating hormone concentrations produced by oxytocin infusion were similar on each day of the cycle and so could not account for the differences seen. Therefore, these results suggest varying renal responsiveness to oxytocin during the reproductive cycle of the female rat.

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“…While the direct effects of estrogen on NP content or gene expression have not been studied in the brain, there is evidence that the steroid environment may influence ANP. For example, it is known that over the course of the estrous cycle there is cyclic variation in ANP content in the hypothalamic paraventricular nucleus (PVN) and dorsal raphe nucleus (45). However, no changes were evident in the MPN or a number of other brain sites, including the arcuate nucleus-median eminence (45).…”

Section: Discussionmentioning

confidence: 99%

“…For example, it is known that over the course of the estrous cycle there is cyclic variation in ANP content in the hypothalamic paraventricular nucleus (PVN) and dorsal raphe nucleus (45). However, no changes were evident in the MPN or a number of other brain sites, including the arcuate nucleus-median eminence (45). Although these results outwardly appear to diminish the likelihood that stimulation of ERs in NP neurons in the AVPv, PVp, and MPN results in altered NP levels, the possibility exists that estrogen effects in this instance may be manifested to a lesser degree at NP-ir perikarya compared to distal portions of the neuron at the level of its axonal target.…”

Section: Discussionmentioning

confidence: 99%

Colocalization of Natriuretic Peptide and Estrogen Receptor Immunoreactivities in Preoptic Nuclei in the Female Rat

Watson

Hutchinson

Langub

et al. 1994

J Neuroendocrinology

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Estrogen IS known to play an important role in regulating reproductive function in female rats through actions exerted at the preoptic area, a part of the brain that is markedly sexually dimorphic and which contains abundant estrogen receptors. A critical question to our understanding of estrogen's action on the brain is to identify the types of neurons that contain estrogen receptors (ER). Previous studies have shown that atrial natriuretic peptide (ANP) is in abundance in the preoptic area, and that ANP and other natriuretic peptides are capable of regulating gonadotropin secretion. In an effort to determine whether ERs are present in natriuretic peptide-immunoreactive (NP-ir) neurons in the preoptic area of the rat, double label immunocytochemistry was performed. Since ER-ir, as demonstrated with antibody H222 is known to be localized predominantly in cell nuciei, while NP-ir is present in the cytoplasm, single cells can be double labeled. Diaminobenzidine tetrahydrochloride was used for localization of NP-ir neurons, while nickel-enhanced diaminobenzidine tetrahydrochloride was used for localization of ER-ir. The results revealed that many nuclei throughout the preoptic area contained neurons that were ER-ir or NP-ir and that a substantial number were double labeled. Cell counts in selected preoptic nuclei and components, including the anteroventral periventricular nucleus, periventricular preoptic nucleus, medial part of the medial preoptic nucleus, and central part of the medial preoptic nucleus revealed that 13.6%, 11.1 %, 13.5%, and 24.4%, respectively, of the NP-ir neurons in these nuclei also contained ER-ir. Collectively, a totai of 14.9% of the NP-ir neurons in these nuclei also contained ER-ir. These results support the hypothesis that estrogen may regulate the activity of NP-ir cells in the preoptic area and thereby may be capable of altering functions associated with NPs in this region of the brain, including not only regulation of gonadotropin secretion, but also control of blood pressure and fluid balance.The preoptic area contains a number of distinct sexually dimorphic nuclei, including the anteroventral periventricular nucleus (AVPv) (1, 2), (also referred to as the anterior component of the medial preoptic nucleus) (3), periventricular preoptic nucleus (PVp) (1, 4), and the medial preoptic nucleus (MPN) (4, 5). These nuclei are characterized by the presence of abundant estrogen receptor (ER)-containing neurons (6-8) and many different neurotransmitters and neuroactive peptides have been localized in neurons within these nuclei (2,4). Natriuretic peptides (NP), including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) have been described in the preoptic area and hypothalamus (9-16) and these compounds are biologically active in brain ( 17-27). ANP, BNP, and CNP share extensive sequence homology, but are coded for by separate genes (15,28,29). Using an antiserum that recognized the ANP precursor, Saper and colleagues ( 10) identif...

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Atrial Natriuretic Factor Concentrations in Discrete Brain Regions, Pituitary, Cardiac Atria and Plasma during the Estrous Cycle in Rats

Cited by 5 publications

References 21 publications

The natriuretic actions of vasopressin in the female rat: variations during the 4 days of the oestrous cycle

The natriuretic actions of vasopressin in the female rat: variations during the 4 days of the oestrous cycle

Renal responses to oxytocin during the 4 days of the oestrous cycle in the rat

Colocalization of Natriuretic Peptide and Estrogen Receptor Immunoreactivities in Preoptic Nuclei in the Female Rat

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