Responses of the PAS-positive pars intermedia cells in the cichlid fish Sarotherodon mossambicus to ambient calcium and background adaptation

Eys, Guillaume J.J.M. van; Bonga, S.E. Wendelaar

doi:10.1007/bf00216529

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…Such responses are not con sistently found in PIPAS cells. For the cichlid fish Oreochromis mossambicus we have shown that these cells do not respond to alLnges in external or internal calcium concen trations and we have concluded that in this species the PIPAS cells are unlikely to be involved in the endocrine control of calcium emtabolism (Van Eys and Wendelaar Bonga 1984). The present data on goldfish support this conclusion.…”

Section: / Pi Pas Cells and Calciumsupporting

confidence: 67%

“…PIPAS cells are exclusively found in teleosts (Ball and Batten 1981). Their function is still in dispute (Ball and Batten 1981;Pang 1981;Ball et al 1982;Olivereau et al 1982a, b;Van Eys and Wendelaar Bonga 1984). In some fish species these cells respond to changes in osmolar ity of the ambient water, or to changes in background re flectivity (Ball and Batten 1981;Van Eys 1980).…”

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confidence: 99%

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Response of PAS-positive cells of the pituitary pars intermedia in the teleost Carassius auratus to acid water

1986

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Summary. The PAS-positive or PIPAS cells in the pars in termedia of goldfish are activated after reduction of the pH of the ambient freshwater from 7.5 to 3.5. The cells increase in number and exhibit a five-fold increase in cell volume. Granular endoplasmic reticulum occupies most of the cytoplasm. Goldfish PIPAS cells (also termed calciumsensitive cells) are thought to have a hypercalcemic func tion. Therefore, their activation in acid water may be caused by the severe drop in plasma calcium concentration follow ing exposure of the fish to low water pH. However, activa tion of the PIPAS cells in response to acidification of the water is not prevented when the calcium concentration of the water is increased to levels that result in hypercalcemia instead of hypocalcemia. Activation of the PIPAS cells oc curs also in fish exposed to acidified freshwater enriched with NaCl to an osmolarity similar to that of the blood. This prevents the reduction in plasma osmolarity and Na ' and Cl" concentrations that follow exposure of goldfish to acidified normal freshwater. Our observations do not support the hypothesis that the PIPAS cells in goldfish pro duce a hypercalcemic hormone, or indeed any hormone involved in calcium metabolism or osmoregulation. The cells may be implicated in ¡icid-base regulation (a character istic of many types offish when exposed to acidified water) but the evidence is indirect.

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Section: / Pi Pas Cells and Calciumsupporting

confidence: 67%

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confidence: 99%

Response of PAS-positive cells of the pituitary pars intermedia in the teleost Carassius auratus to acid water

1986

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Environmental influences on prolactin cell development in the cyprinodont fish, Cynolebias whitei

Kemenade

Bonga

1984

Cell Tissue Res.

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Summary.A combined immunocytochemical and morphometric study on the development of the prolactin (PRL) cells of the annual cyprinodont Cynolebias whitei, trans ferred as newly hatched larvae to water with different salini ties and/or C a2 ' -concentrations, was carried out. The per centage of the pituitary volume occupied by PRL cells and the affinity of PRL cells for immunocytochemical staining were used as criteria for their activity. Exposure of the lar vae for one day to salt water (260 mOsm/kg) led to a signifi cant reduction in the pituitary volume occupied by PRL cells, indicating an osmoregulatory function of PRL shortly after hatching. In fish reared in diluted artificial seawater (70 and 260 mOsm/kg) or Na f -enriched fresh water the development of PRL cells was significantly retarded, but such an effect was not observed in fish placed in Ca2 -enriched fresh water. These experiments show that in C. whitei the development and activity of PRL cells are influenced by changes in environmental osmolarity and not by changes in ambient Ca2 -concentration.

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The effect of water acidification on prolactin cells and pars intermedia PAS-positive cells in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus and Carassius auratus

et al. 1984

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Although exposure to acid water (pH 3.5) induces severe and prolonged reduction in plasma osmolarity and total plasma calcium concentration in tilapia (Oreochromis mossambicus) and goldfish (Carassius auratus), the responses of the hypophyseal cells are clearly different. In tilapia, the size of the rostral pars distalis of the pituitary gland is enlarged as a result of the increase in size and number of prolactin cells. The pars intermedia PAS-positive (PIPAS) cells are not noticeably changed. Conversely, in goldfish, prolactin cells are unaffected, whereas the number of enlarged PIPAS cells increases markedly. Stimulation of prolactin secretion may be responsible for the partial restoration of plasma osmolarity and calcium levels observed in tilapia after two weeks exposure to acid water. Prolactin cells apparently play a role in the adaptation to acid stress by counteracting osmoregulatory disturbances. Goldfish show no restoration of plasma osmolarity during the course of the experiment. Plasma calcium levels tend to increase. Although prolactin may have an osmoregulatory function in goldfish under steady state conditions, goldfish prolactin cells do not seem to participate in the physiological adaptation to environmental changes that disturb water and ion homeostasis. The function of PIPAS cells in tilapia remains unclear and is apparently unconnected with ion regulation. The observations on these cells in goldfish are consistent with the hypercalcemic activity suggested for them.

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Responses of the PAS-positive pars intermedia cells in the cichlid fish Sarotherodon mossambicus to ambient calcium and background adaptation

Cited by 4 publications

References 18 publications

Response of PAS-positive cells of the pituitary pars intermedia in the teleost Carassius auratus to acid water

Response of PAS-positive cells of the pituitary pars intermedia in the teleost Carassius auratus to acid water

Environmental influences on prolactin cell development in the cyprinodont fish, Cynolebias whitei

The effect of water acidification on prolactin cells and pars intermedia PAS-positive cells in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus and Carassius auratus

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