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 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 In goldfish the discriminative ability for odours persists after reduction of the olfactory epithelium, and rapidly returns after olfactory nerve axotomy and crossing bulbs

2000 ◽  
Vol 355 (1401) ◽  
pp. 1219-1223 ◽  
Author(s):  
Hans Peter Zippel
Keyword(s):  
Amino Acid ◽  
Olfactory Epithelium ◽  
Functional Recovery ◽  
Olfactory System ◽  
Olfactory Nerve ◽  
Sensory Cells ◽  
Similar Concentration ◽  
Olfactory Bulbs ◽  
Discriminative Ability ◽  
Bilateral Lesions

Goldfish are ideal vertebrates for the study of regeneration within the peripheral and the central olfactory system. The present behavioural investigations studied the effects of bilateral lesions on the animals' ability to qualitatively discriminate two amino acids (107 -6 M) and their performance in two more difficult tasks: (i) rewarded amino acid applied in a lower concentration, and (ii) rewarded stimulus contaminated. A 50 and 85% reduction of the olfactory epithelium resulted in no recordable behavioural deficit. After axotomy of olfactory nerves and lateral olfactory tractotomy, fishes were anosmic for seven to ten days. Following replacement of sensory cells in the epithelium, and after regeneration of olfactory tract fibres a full functional recovery, i.e. a highly specific regeneration, was recorded. After three surgical modifications of the olfactory bulbs' position, (i) crossing olfactory tracts and bulbs, (ii) crossing tracts and turning bulbs, and (iii) turning bulbs upside down, a full functional recovery was recorded for amino-acid discrimination in a similar concentration. A permanent, and similar slight deficit was, however, found during application of different concentrations, and of contaminated stimuli when medial lateral halves of the bulb were in ‘incorrect’ position (i) and (iii), or olfactory bulbs were positioned in the vicinity of the contralateral epithelium (i) and (ii).

scholarly journals GABA receptors in the olfactory epithelium of the gilthead seabream (Sparus aurata)

2022 ◽  
Author(s):  
Rita A. Costa ◽  
Zélia Velez ◽  
Peter C. Hubbard
Keyword(s):  
Gabaa Receptor ◽  
Olfactory Epithelium ◽  
Gabaa Receptors ◽  
Gaba Receptors ◽  
Sparus Aurata ◽  
Receptor Protein ◽  
High Pco2 ◽  
Gilthead Seabream ◽  
Exact Function ◽  
Gabaa Receptor Antagonist

Exposure to high PCO2/low pH seawater induces behavioural alterations in fish; a possible explanation for this is a reversal of Cl−/HCO3− currents through GABAA receptors (the GABAA receptor theory). However, the main evidence for this is that gabazine, a GABAA receptor antagonist, reverses these effects when applied to the water, assuming that exposure to systems other than the CNS would be without effect. Here, we show the expression of both metabotropic and ionotropic GABA receptors, and the presence of GABAA receptor protein, in the olfactory epithelium (OE) of gilthead seabream. Furthermore, exposure of the OE to muscimol (a specific GABAA receptor agonist) increases or decreases the apparent olfactory sensitivity to some odorants. Thus, although the exact function of GABAA receptors in the OE is not yet clear, this may complicate the interpretation of studies wherein water-borne gabazine is used to reverse the effects of high CO2 levels on olfactory-driven behaviour in fish.

Olfactory responses of a euryhaline fish, the rainbow trout: adaptation of olfactory receptors to sea water and salt-dependence of their responses to amino acids

1996 ◽  
Vol 199 (2) ◽  
pp. 303-310 ◽  
Author(s):  
T Shoji ◽  
KI Fujita ◽  
E Furihata ◽  
K Kurihara
Keyword(s):  
Amino Acids ◽  
Rainbow Trout ◽  
Fresh Water ◽  
Olfactory Epithelium ◽  
Sea Water ◽  
Olfactory Receptors ◽  
Large Change ◽  
Pond Water ◽  
Olfactory Nerve ◽  
Euryhaline Fish

Salmonid fishes are able to survive in both fresh water and sea water. Concentrations of NaCl in fresh water and sea water are 0.5 and 493 mmol l-1, respectively, and, hence, salt concentrations in the medium at the olfactory epithelium are greatly changed when the fish migrate between fresh water and sea water. We used the rainbow trout, which is a salmonid fish, to examine the adaptation mechanisms of the olfactory receptors to high concentrations of salts in sea water. Application of sea water to the olfactory epithelium elicited only a very small response in the olfactory nerve, but 500 mmol l-1 NaCl elicited a large response which did not adapt to a spontaneous level with time. It is considered that the olfactory nerve becomes fatigued when the olfactory epithelium is exposed to 500 mmol l-1 NaCl for long periods. We found that the presence of 10 mmol l-1 Ca2+ in sea water inhibited the response to 500 mmol l-1 NaCl, suggesting that Ca2+ in sea water is essential for adaptation of the olfactory receptors to sea water. In the second part of the study, we examined whether the olfactory nerve responses to amino acids, potent stimulants for fish, were altered between fresh water and sea water. The magnitudes of the responses to the six amino acids examined were similar in artificial pond water and artificial sea water, indicating that a large change in NaCl concentration between fresh and sea water does not affect the olfactory nerve responses to amino acids. We used fish reared in fresh water and fish acclimated to sea water and obtained similar results. It was concluded that the tolerance of the olfactory receptors for large changes in osmotic pressure is not acquired while fish are maintained in fresh or sea water, but that the receptors of these euryhaline fish naturally provide the tolerance.

Olfactory mucosal and neural responses in the frog

1962 ◽  
Vol 203 (2) ◽  
pp. 353-358 ◽  
Author(s):  
Maxwell Mark Mozell
Keyword(s):  
Stimulus Intensity ◽  
Olfactory Epithelium ◽  
Flow Rate ◽  
Olfactory Nerve ◽  
Neural Responses ◽  
Criterion Measure ◽  
Repeated Stimulation ◽  
Two Measures ◽  
Electrophysiological Technique

A comparatively recent electrophysiological technique for studying peripheral olfactory events is to record sustained negative potentials from the olfactory epithelium. This method is rapidly replacing the older technique of recording multifiber discharges from the olfactory nerve or bulb. Therefore, the extent to which the results from the two methods correlate with each other was studied by simultaneously recording from the nerve and from the mucosa under several conditions. Although most often parallel, some differences between the two measures were found. Their response maxima did not always temporally coincide. Their amplitudes did not always correlate. Certain stimuli reduced subsequent mucosal responses but not the neural. Repeated stimulation sometimes produced similar differences. Finally, the two responses were not linearly related as a function of stimulus intensity or flow rate. However, for reasons discussed, it is difficult to conclude that these discrepancies necessarily reflect unfavorably upon the reliability of the mucosal potential as the criterion measure of peripheral olfactory activity. Nevertheless, the mucosal potential should not be accepted unequivocally as such a criterion measure until it is more thoroughly understood.

Genetic parameters for quality traits by non-invasive methods and their G x E interactions in ocean cages and estuaries on gilthead seabream (Sparus aurata)

Aquaculture ◽  
2021 ◽  
Vol 537 ◽  
pp. 736462
Author(s):  
I. Elalfy ◽  
H.S. Shin ◽  
D. Negrín-Báez ◽  
A. Navarro ◽  
M.J. Zamorano ◽  
...  
Keyword(s):  
Genetic Parameters ◽  
Sparus Aurata ◽  
Gilthead Seabream ◽  
Quality Traits ◽  
Non Invasive

Effects of subcutaneous injection of λ/κ‐carrageenin on the immune and liver antioxidant status of gilthead seabream ( Sparus aurata )

2021 ◽  
Author(s):  
José Carlos Campos‐Sánchez ◽  
Francisco A. Guardiola ◽  
José María García Beltrán ◽  
Diana Ceballos‐Francisco ◽  
María Ángeles Esteban
Keyword(s):  
Subcutaneous Injection ◽  
Antioxidant Status ◽  
Sparus Aurata ◽  
Gilthead Seabream

scholarly journals Extinction reverses olfactory fear-conditioned increases in neuron number and glomerular size

2015 ◽  
Vol 112 (41) ◽  
pp. 12846-12851 ◽  
Author(s):  
Filomene G. Morrison ◽  
Brian G. Dias ◽  
Kerry J. Ressler
Keyword(s):  
Olfactory Bulb ◽  
Learning And Memory ◽  
Olfactory Epithelium ◽  
Olfactory System ◽  
Structural Changes ◽  
Freezing Behavior ◽  
Extinction Training ◽  
Odor Stimulus ◽  
Main Olfactory Epithelium ◽  
Odor Learning

Although much work has investigated the contribution of brain regions such as the amygdala, hippocampus, and prefrontal cortex to the processing of fear learning and memory, fewer studies have examined the role of sensory systems, in particular the olfactory system, in the detection and perception of cues involved in learning and memory. The primary sensory receptive field maps of the olfactory system are exquisitely organized and respond dynamically to cues in the environment, remaining plastic from development through adulthood. We have previously demonstrated that olfactory fear conditioning leads to increased odorant-specific receptor representation in the main olfactory epithelium and in glomeruli within the olfactory bulb. We now demonstrate that olfactory extinction training specific to the conditioned odor stimulus reverses the conditioning-associated freezing behavior and odor learning-induced structural changes in the olfactory epithelium and olfactory bulb in an odorant ligand-specific manner. These data suggest that learning-induced freezing behavior, structural alterations, and enhanced neural sensory representation can be reversed in adult mice following extinction training.

scholarly journals Aflatoxicosis Dysregulates the Physiological Responses to Crowding Densities in the Marine Teleost Gilthead Seabream (Sparus aurata)

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 753
Author(s):  
Andre Barany ◽  
Juan Fuentes ◽  
Gonzalo Martínez-Rodríguez ◽  
Juan Miguel Mancera
Keyword(s):  
Mrna Expression ◽  
Sparus Aurata ◽  
Stocking Density ◽  
Head Kidney ◽  
Dietary Exposure ◽  
Experimental Period ◽  
Gilthead Seabream ◽  
Marine Teleost ◽  
Lipid Metabolites ◽  
Period Duration

Several studies in fish have shown that aflatoxin B1 (AFB1) causes a disparity of species-dependent physiological disorders without compromising survival. We studied the effect of dietary administration of AFB1 (2 mg AFB1 kg−1 diet) in gilthead seabream (Sparus aurata) juveniles in combination with a challenge by stocking density (4 vs. 40 g L−1). The experimental period duration was ten days, and the diet with AFB1 was administered to the fish for 85 days prior to the stocking density challenge. Our results indicated an alteration in the carbohydrate and lipid metabolites mobilization in the AFB1 fed group, which was intensified at high stocking density (HSD). The CT group at HSD increased plasma cortisol levels, as expected, whereas the AFB1-HSD group did not. The star mRNA expression, an enzyme involved in cortisol synthesis in the head kidney, presented a ninefold increase in the AFB1 group at low stocking density (LSD) compared to the CT-LSD group. Adenohypophyseal gh mRNA expression increased in the AFB1-HSD but not in the CT-HSD group. Overall, these results confirmed that chronic AFB1 dietary exposure alters the adequate endocrinological physiological cascade response in S. aurata, compromising the expected stress response to an additional stressor, such as overcrowding.

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