Glomerular actions of arginine vasotocin in the in situ perfused trout kidney

Amer, Shehla; Brown, J. Anne

doi:10.1152/ajpregu.1995.269.4.r775

Cited by 49 publications

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“…The TmG found in this study is similar to findings in another in vivo study (Gray and Brown, 1985;Table·2). However, it is approximately double compared with findings on in situ perfused trout kidney studies (Amer and Brown, 1995;Brown et al, 2000;Table·2). Part of these differences could be accounted for by variations in experimental temperatures, as TmG varies with temperature, with higher temperatures yielding higher TmGs (MacKay and Beatty, 1967).…”

Section: Discussionmentioning

confidence: 86%

Renal regulation of plasma glucose in the freshwater rainbow trout

Bucking

Wood

2005

Journal of Experimental Biology

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SUMMARY This study examined the effects of prolonged hyperglycemia on renal handling of glucose and explored the in vivo pharmacological effects of phlorizin on glucose transport in the rainbow trout. The transport of glucose was examined by experimentally elevating the rate of renal glucose reabsorption via infusion of the fish with exogenous glucose at a rate of 70 μmol kg–1 h–1 and by inactivating the glucose transporters via the simultaneous administration of phlorizin (1 μmol kg–1h–1). Glucose was reabsorbed against a concentration gradient, until plasma glucose levels reached ∼22 μmol l–1 and the transport maximum of glucose in the kidney(∼145 μmol kg–1 h–1) was exceeded. At this point, glucose was lost to the urine, resulting in glucosuria. Glucosuria affected water reabsorption, approximately doubling the water clearance ratio,and resulted in osmotic diuresis. This in turn reduced Na+reabsorption, increasing the amount lost to the urine from 0.5% to 2% of the filtered load. Glucose reabsorption was found to be correlated with Na+ reabsorption, though the latter was almost 10-fold higher than glucose transport rates. Phlorizin treatment reduced glucose reabsorption,although it did not block it entirely until 48–72 h of infusion. The glucosuria resulting from the blockade of the glucose transporters resulted in a similar osmotic diuresis and a greater Na+ loss to the urine (9%of filtered load). The results are discussed with respect to the net renal`wasting' of glucose and the detrimental osmoregulatory and ionoregulatory effects associated with glucosuria caused by carbohydrate-rich diets.

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Section: Discussionmentioning

confidence: 86%

Renal regulation of plasma glucose in the freshwater rainbow trout

Bucking

Wood

2005

Journal of Experimental Biology

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“…In contrast to its predominant tubular effects in mammals, the antidiuretic effect of AVT in fish is achieved by decreasing glomerular filtration rates which results in an increase in water reabsorption and a decrease in urine flow (Amer and Brown, 1995;Konno et al, 2010;Warne et al, 2002). As a first investigation of this hypothesis we collected data on volumes of urine stored by dominant and subordinate males.…”

Section: Discussionmentioning

confidence: 99%

“…Since in this species dominant males use urine to communicate social status (Almeida et al, 2005;Barata et al, 2007) and since AVT is known to have an antidiuretic effect in fish by decreasing glomerular filtration rate (Amer and Brown, 1995;Balment et al, 1993), we have also tested the hypothesis that higher volumes of urine stored by dominant males are associated with lower levels of systemic AVT. Therefore, this study has the following specific aims:…”

Section: Introductionmentioning

confidence: 99%

Brain levels of arginine–vasotocin and isotocin in dominant and subordinate males of a cichlid fish

Almeida

Gozdowska

Kulczykowska

et al. 2012

Hormones and Behavior

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The nonapeptides arginine-vasotocin (AVT) and isotocin (IT), which are the teleost homologues of argininevasopressin and oxytocin in mammals, have well established peripheral effects on osmoregulation and stress response, and central effects on social behavior. However, all studies that have looked so far into the relationship between these nonapeptides and social behavior have used indirect measures of AVT/IT activity (i.e. immunohistochemistry of AVT/IT immunoreactive neurons, or AVT/IT or their receptors mRNA expression with in situ hybridization or qPCR) and therefore direct measures of peptide levels in relation to social behavior are still lacking. Here we use a recently developed high-performance liquid chromatography analysis with fluorescence detection (HPLC-FL) method to quantify the levels of both AVT and IT in macro-dissected brain areas [i.e. olfactory bulbs, telencephalon, diencephalon, optic tectum, cerebellum, and hindbrain (= rhombencephalon minus cerebellum)] and pituitary of dominant and subordinate male cichlid fish (Oreochromis mossambicus). The pituitary shows higher levels of both peptides than any of the brain macroareas, and the olfactory bulbs have the highest AVT among all brain areas. Except for IT in the telencephalon there is a lack of correlations between central levels and pituitary peptide levels, suggesting an independent control of hypophysial and CNS nonapeptide secretion. There were also no correlations between AVT and IT levels either for each brain region or for the pituitary gland, suggesting a decoupled activity of the AVT and IT systems at the CNS level. Subordinate AVT pituitary levels are significantly higher than those of dominants, and dominant hindbrain IT levels are significantly higher than those of subordinates, suggesting a potential involvement of AVT in social stress in subordinate fish and of IT in the regulation of dominant behavior at the level of the hindbrain. Since in this species dominant males use urine to communicate social status and since AVT is known to have an antidiuretic effect, we have also investigated the effect of social status on urine storage. As predicted, dominant males stored significantly more urine than subordinates. Given these results we suggest that AVT/IT play a key role in orchestrating social phenotypes, acting both as central neuromodulators that promote behavioral plasticity and as peripheral hormones that promote integrated physiological changes.

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“…The presence of these receptors in a variety of tissues, such as the brain, liver, gills and head kidney, has previously been demonstrated while assessing the effects of AVT and IT administration or even analysing its mRNA expression (e.g. Motais and Maetz, 1967;Henderson and Wales, 1974;Guibbolini et al, 1988;Guibbolini et al, 2000;Amer and Brown, 1995;Conklin et al, 1996;Konno et al, 2009;Konno et al, 2010;Lema, 2010;Martos-Sitcha et al, 2014a), suggesting that physiological processes within these tissues are regulated by the vasotocinergic and/or isotocinergic systems. Interestingly, our results …”

Section: Expression Of the Avt And It Receptor Genes Following Cortismentioning

confidence: 96%

Cortisol modulates vasotocinergic and isotocinergic pathways in the gilthead sea bream (Sparus aurata, Linnaeus 1758)

Cádiz

Román-Padilla

Gozdowska

et al. 2014

Journal of Experimental Biology

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In the present study, we assessed the responses of the vasotocinergic and isotocinergic systems to chronic stress induced by cortisol administration in the gilthead sea bream (Sparus aurata). Pituitary and plasma arginine vasotocin (AVT) and isotocin (IT) levels, as well as hypothalamic pro-vasotocin (pro-VT) and pro-isotocin (pro-IT) mRNA expression levels, were analysed. In addition, the mRNA levels of three receptors, AVTR type V1a2, AVTR type V2 and ITR, were analysed in several target organs associated with the following physiological processes: (i) integration and control (hypothalamus), (ii) metabolism and its control (liver and hypothalamus), (iii) osmoregulation (gills) and (iv) stress response (head kidney). Specimens were injected intraperitoneally with slow-release implants (5 μL g −1 body mass) containing coconut oil alone (control group) or with cortisol (50 μg g −1 body mass; cortisol group). Both AVT and IT synthesis and release were correlated with plasma cortisol values, suggesting a potential interaction between both hormonal systems and cortisol administration. Our results suggest that the activation of hepatic metabolism as well as the hypothalamic control of metabolic processes provide the energy necessary to overcome stress, which could be partly mediated by AVTRs and ITR. Upregulation of branchial AVT and IT receptor expression following cortisol treatment suggests an involvement of the vasotocinergic and isotocinergic systems in the regulation of ion channels/transporters during stressful situations. Finally, changes in AVT and IT receptor mRNA expression in the head kidney suggest these nonapeptides participate in feedback mechanisms that regulate the synthesis/release of cortisol. Our results indicate a relationship between cortisol and both the vasotocinergic and isotocinergic systems during simulated chronic stress in S. aurata.

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Glomerular actions of arginine vasotocin in the in situ perfused trout kidney

Cited by 49 publications

References 0 publications

Renal regulation of plasma glucose in the freshwater rainbow trout

Renal regulation of plasma glucose in the freshwater rainbow trout

Brain levels of arginine–vasotocin and isotocin in dominant and subordinate males of a cichlid fish

Cortisol modulates vasotocinergic and isotocinergic pathways in the gilthead sea bream (Sparus aurata, Linnaeus 1758)

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