scholarly journals Olfactory sensitivity to changes in environmental [Ca2+] in the freshwater teleost Carassius auratus: an olfactory role for the Ca2+-sensing receptor?

2002 ◽  
Vol 205 (18) ◽  
pp. 2755-2764 ◽  
Author(s):  
P. C. Hubbard ◽  
P. M. Ingleton ◽  
L. A. Bendell ◽  
E. N. Barata ◽  
A. V. M. Canário
Keyword(s):  
Olfactory System ◽  
Carassius Auratus ◽  
Sea Water ◽  
Sparus Aurata ◽  
In Situ Hybridisation ◽  
Extracellular Recording ◽  
Hill Coefficient ◽  
Olfactory Sensitivity ◽  
Goldfish Carassius Auratus

SUMMARY Olfactory sensitivity to changes in environmental Ca2+ has been demonstrated in two teleost species; a salmonid (Oncorhynchus nerka)and a marine/estuarine perciform (Sparus aurata). To assess whether this phenomenon is restricted to species that normally experience large fluctuations in external ion concentrations (e.g. moving from sea water to fresh water) or is present in a much wider range of species, we investigated olfactory Ca2+ sensitivity in the goldfish (Carassius auratus), which is a stenohaline, non-migratory freshwater cyprinid. Extracellular recording from the olfactory bulb in vivo by electroencephalogram (EEG) demonstrated that the olfactory system is acutely sensitive to changes in external Ca2+ within the range that this species is likely to encounter in the wild (0.05-3 mmol l-1). The olfactory system responded to increases in external calcium with increasing bulbar activity in a manner that fitted a conventional Hill plot with an apparent EC50 of 0.9±0.3 mmol l-1 (close to both ambient and plasma free [Ca2+]) and an apparent Hill coefficient of 1.1±0.3 (means ± S.E.M., N=6). Thresholds of detection were below 50 μmol l-1. Some olfactory sensitivity to changes in external [Na+] was also recorded, but with a much higher threshold of detection (3.7 mmol l-1). The olfactory system of goldfish was much less sensitive to changes in [Mg2+] and [K+]. Preliminary data suggest that Ca2+ and Mg2+ are detected by the same mechanism, although with a much higher affinity for Ca2+. Olfactory sensitivity to Na+ may warn freshwater fish that they are reaching the limit of their osmotic tolerance when in an estuarine environment. Olfaction of serine, a potent odorant in fish, was not dependent on the presence of external Ca2+ or Na+. Finally, the teleost Ca2+-sensing receptor (Ca-SR) was shown to be highly expressed in a subpopulation of olfactory receptor neurones by both immunocytochemistry and in situ hybridisation. The olfactory sensitivity to Ca2+ (and Mg2+) is therefore likely to be mediated by the Ca-SR. We suggest that olfactory Ca2+ sensitivity is a widespread phenomenon in teleosts and may have an input into the physiological mechanisms regulating internal calcium homeostasis.

scholarly journals Olfactory sensitivity to changes in environmental [Ca(2+)] in the marine teleost Sparus aurata

2000 ◽  
Vol 203 (24) ◽  
pp. 3821-3829 ◽  
Author(s):  
P.C. Hubbard ◽  
E.N. Barata ◽  
A.V. Canario
Keyword(s):  
Olfactory Epithelium ◽  
Olfactory System ◽  
Sea Water ◽  
Sparus Aurata ◽  
Specific Effect ◽  
Olfactory Nerve ◽  
Olfactory Response ◽  
Hill Coefficient ◽  
Gilthead Seabream ◽  
Continuous Exposure

Estuarine and/or migratory teleosts may experience large and rapid changes in external [Ca(2+)]. Previous studies have largely centred on the physiological mechanisms that maintain a constant plasma [Ca(2+)] in the face of such external fluctuations, but little work has been directed to examining how these changes may originally be detected. We present evidence that the olfactory system of the gilthead seabream (Sparus aurata) is highly sensitive to reductions in environmental [Ca(2+)] and suggest a possible mechanism by which this may be mediated. Multi-unit extracellular recordings were made from the olfactory nerve of Sparus aurata while the [Ca(2+)] of artificial sea water flowing over the olfactory epithelium was varied from 10 to 0 mmol l(−)(1). Reductions in [Ca(2+)] caused a large, non-accommodating increase in the firing rate of the olfactory nerve (apparent IC(50)=1.67+/−0.26 mmol l(−)(1), apparent Hill coefficient=−1.22+/−0.14; means +/− s.e.m., N=6). This response was not due to the concomitant reduction in osmolality and was specific for Ca(2+). During continuous exposure of the olfactory epithelium to Ca(2+)-free sea water, the apparent IC(50) and Hill coefficient in response to increases in [Ca(2+)] were 0.48+/−0.14 mmol l(−)(1) and −0.76+/−0.16 (means +/− s.e.m., N=6), respectively, suggesting an adaptation of the Ca(2+)-sensing system to low-[Ca(2+)] environments. Ca(2+) is intimately involved in signal transduction in the olfactory receptor neurones, but our data support a true olfactory response, rather than a non-specific effect to lowering of external [Ca(2+)]. The absence of Ca(2+) from sea water only partially and temporarily blunted the olfactory response to the odorant l-serine; the response amplitude recovered to control levels within 20 min. This suggests that the olfactory system in general is able to adapt to low-[Ca(2+)] environments. We suggest that the Ca(2+)sensitivity is mediated by an extracellular Ca(2+)-sensing receptor similar to the recently characterized mammalian Ca(2+)-sensing receptor.

scholarly journals In Vivo Testing System for Determining the Estrogenic Activity of Endocrine-Disrupting Chemicals(EDCs) in Goldfish (Carassius auratus).

2001 ◽  
Vol 47 (2) ◽  
pp. 213-218 ◽  
Author(s):  
Hiroshi Ishibashi ◽  
Katsuyasu Tachibana ◽  
Mutsuyosi Tsuchimoto ◽  
Kiyoshi Soyano ◽  
Yasuhiro Ishibashi ◽  
...  
Keyword(s):  
Carassius Auratus ◽  
Estrogenic Activity ◽  
Endocrine Disrupting Chemicals ◽  
Testing System ◽  
Goldfish Carassius Auratus ◽  
Endocrine Disrupting ◽  
In Vivo Testing

In-vivo evaluation of dopamine receptor-mediated inhibition of gonadotrophin secretion from the pituitary gland of the goldfish, Carassius auratus

1987 ◽  
Vol 114 (3) ◽  
pp. 449-458 ◽  
Author(s):  
R. J. Omeljaniuk ◽  
S. H. Shih ◽  
R. E. Peter
Keyword(s):  
Dopamine Receptor ◽  
Carassius Auratus ◽  
Time Course ◽  
Dopamine Antagonists ◽  
Serum Concentrations ◽  
In Vivo Evaluation ◽  
Goldfish Carassius Auratus ◽  
Dopamine Receptor Antagonists ◽  
The Brain

ABSTRACT Dopamine acts directly on the pituitary to modulate gonadotrophin (GtH) secretion in goldfish (Carassius auratus). In the light of this important role for dopamine in the regulation of goldfish reproduction, this investigation was designed to evaluate the receptor specificity of this dopamine inhibition and to describe the use of domperidone, a specific dopamine D2-receptor antagonist, in the manipulation of pituitary function in goldfish. To investigate the specificity of dopamine inhibition of GtH secretion, selected dopamine receptor antagonists were injected i.p. to block dopamine receptors thereby increasing GtH secretion as reflected by increased serum concentrations of GtH. Serum GtH levels were significantly increased by the active stereoisomer (−)-sulpiride in a dose-related fashion; (+)-sulpiride had no effect. Comparison of dopamine antagonists at low doses indicated that only domperidone and pimozide caused significant increases in serum concentrations of GtH. Dopamine antagonists potentiated the action of a gonadotrophin-releasing hormone analogue (GnRH-A) with an order of potency of domperidone = pimozide > metoclopramide = fluphenazine. [3H]Domperidone, injected i.p. with unlabelled domperidone, entered the blood and achieved maximum concentrations 12 h after injection, but did not accumulate in the brain in appreciable amounts. Gonadal 3H radioactivity was usually equal to or in excess of blood radioactivity, while [3H]domperidone was highly concentrated in the pituitary in a time-dependent fashion, with maximal accumulation occurring 24 h after injection. The time-course of pituitary accumulation of [3H]domperidone correlated well with the temporal increase in serum GtH levels in response to i.p. injected domperidone or domperidone plus an analogue of LHRH. Domperidone increased serum concentrations of GtH in a dose-related fashion; an analogue of salmon GnRH (sGnRH-A) increased the sensitivity and magnitude of the serum GtH response to domperidone. Serum concentrations of GtH were increased by sGnRH-A in a dose-related fashion; a low dose of domperidone substantially increased the sensitivity of the serum GtH response to sGnRH-A. These results indicate that dopamine inhibits GtH secretion from the goldfish pituitary by acting through a specific mechanism mediated by a dopamine D2 receptor. Domperidone increased serum concentrations of GtH, potentiated the action of gonadotrophin-releasing hormones and did not pass into the brain after i.p. injection into goldfish. The data also suggest that dopamine and GnRH, although acting through different receptors, influence the effect of each other on GtH release. J. Endocr. (1987) 114, 449–458

Sublethal effect of DDT on osmotic and ionic regulation by the goldfish Carassius auratus

1974 ◽  
Vol 52 (6) ◽  
pp. 739-744 ◽  
Author(s):  
Melvin Weisbart ◽  
Daniel Feiner
Keyword(s):  
Carassius Auratus ◽  
Total Lipid Content ◽  
Sublethal Effect ◽  
Goldfish Carassius Auratus ◽  
In Vivo Experiments ◽  
Plasma Electrolytes ◽  
Freshwater System ◽  
Higher Doses

Goldfish treated with up to 35 parts per billion (ppb), 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane(DDT) for up to 330 h in a running freshwater system showed significant but inconsistent decreases in plasma osmotic and sodium concentrations and a significant but inconsistent increase in potassium concentrations.Goldfish exposed to 17.5 ppb DDT for 330 h and subsequently transferred to brackish water (synthetic) showed no significant differences in plasma electrolytes from solvent-treated goldfish.No correlation between pesticide concentrations and total lipid content of individual goldfish was found but for one exception. Fish exposed to higher doses showed higher pesticide levels in their bodies.The lack of correlation between in vitro and in vivo experiments is discussed.

scholarly journals Influence of the diet on the microbial diversity of faecal and gastrointestinal contents in gilthead sea bream (Sparus aurata) and intestinal contents in goldfish (Carassius auratus)

2011 ◽  
Vol 78 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Flávia Cristina de Paula Silva ◽  
Jacques Robert Nicoli ◽  
José Luiz Zambonino-Infante ◽  
Sadasivam Kaushik ◽  
François-Joël Gatesoupe
Keyword(s):  
Microbial Diversity ◽  
Carassius Auratus ◽  
Sparus Aurata ◽  
Gilthead Sea Bream ◽  
Sea Bream ◽  
Goldfish Carassius Auratus ◽  
Intestinal Contents
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