Olfactory sensitivity to catecholamines and their metabolites in the goldfish

The current study assessed the olfactory sensitivity of the goldfish (Carassius auratus L.) to the catecholamines, their immediate precursors and metabolites by use of the electro-olfactogram (EOG). The olfactory system of the goldfish was found to be sensitive to both adrenaline and dopamine with thresholds of detection of 10(-7.8) and 10(-7.9) M respectively, but less so to noradrenaline (threshold of detection 10(-6.3) M). The 3-O-methoxy metabolites (metadrenaline, normetadrenaline and 3-O-methoxytyramine) evoked larger amplitude EOGs than the non-metabolized form with lower thresholds of detection. However, the olfactory system was less sensitive to the amino acid precursors L-tyrosine and L-DOPA, and markedly less so to the alpha-deaminated metabolites (3,4-dihydroxyphenyl glycol, 3,4-dihydroxy mandelic acid and dihydroxyphenyacetic acid). Sensitivity to metabolites, both alpha-deaminated and 3-O-methoxylated, was similar to the alpha-deaminated forms. Cross-adaptation studies suggested that, while there is some degree of commonality of the receptor mechanisms with L-tyrosine and L-serine, a proportion of the response to the catecholamines is due to distinct receptor subtypes. Similarly, the 3-O-methoxy metabolites also had (a) separate receptor mechanism(s), although, again, there was overlap with the adrenaline/dopamine receptor site(s). Presence of the alpha-adrenoreceptor antagonist prazosin or the peripheral DA(2) dopamine receptor antagonist domperidone caused partial attenuation of the EOG responses to adrenaline and dopamine, but had much less effect on the responses to their 3-O-methoxy metabolites. The beta-adrenoreceptor antagonist sotalol had no such effect. This suggests that the olfactory catecholamine receptors are structurally and functionally distinct from systemic adreno- and dopamine receptors. The current study raises the possibility that release of catecholamines or their 3-O-methoxy metabolites to the water may play a role in chemical communication.     

Stimulation of ethylene production by catecholamines and phenylethylamine in potato cell suspension cultures

The catecholamines (50 M dopamine, 50 M norepinephrine and 100 M epinephrine) and phenylethylamine (200 M) were found to stimulate ethylene production in potato suspension cultures. When 100 M amino-oxyacetic acid was added together with epinephrine, ethylene release returned to control levels. The endogenous 1-aminocyclopropane-1-carboxylic acid levels were increased in parallel with the release of ethylene, suggesting that the observed effect probably occurs via regulation of aCC synthase. Our results suggest that there is a link between these naturally occurring monoamines and ethylene in plants.Abbreviations AOA amino-oxyacetic acid - ACC 1-aminocyclopropane-1-carboxylic acid - DA dopamine - NE norepinephrine - E epinephrine - CA catecholamines - PEA phenylethylamine     

Regional turnover of norepinephrine and dopamine in rat brain following acute exposure to air ions

Exposure to air ions has been reported to influence serotonin (5HT), although critical reviews of these studies and previous measurements in our laboratory of the concentration, release, and utilization of brain 5HT indicate that neither the data nor the interpretations of the data are particularly convincing. Measurements of other possibly relevant neurotransmitter systems--norepinephrine (NE) and dopamine (DA)--were made in brain regions selected because of their importance in the modulation of brain functions relating to motivation, arousal, endocrine function, and motor activity, all responses that have been reported to be influenced by air ion exposure. Results indicate that exposure of male Holtzman rats to high concentrations (5.0 X 10(5)/cm3) of positive or negative air ions or to DC electric fields (3.0 kV/m) for periods up to 66 h failed to affect the concentration of NE or DA significantly in any of the brain regions.     

An analysis of avoidance generalization and food preference transitivity in goldfish,Carassius auratus

To examine the effect of novelty in food selection by fishes, goldfish were trained by feeding them on red or green food pellets. Individual fish and fish in shoals of two, three, and five were then given a choice between equal numbers of familiar pellets and novel (yellow) pellets. In experimental groups, the yellow pellets were soaked in 15% quinine hydrochloride to make them unpalatable. Fish were next presented with equal numbers of familiar and a second novel pellet. It was expected that fish would generalize from their experience with the unpalatable pellets and demonstrate avoidance to sampling a second novel food item. However, as groups, neither controls nor experimentals were reluctant to sample the second novel pellets. Also, fish did not eat significantly more familiar than novel pellets when both were palatable. A third set of experiments examined food preference transitivity in which each pellet type was presented alone and in three pair-wise combinations to individual fish. Although red and yellow pellets were preferred over green, they were preferred equally, indicating an absence of transitivity in pellet choice and, perhaps, a “preference” for a mixture of red and yellow pellets.     

Changes in catecholamine levels and turnover rates in hypothalamic,vocal control,and auditory nuclei in male zebra finches during development

The catecholamines norepinephrine (NE) and dopamine (DA) have been implicated in the sexual differentiation of brain and behavior and in species-specific learning in several species. To determine if these neurotransmitters might be involved in sexual differentiation of the vocal control system and song learning in male zebra finches, NE and DA levels and turnover rates were quantified in 10 behaviorally relevant brain nuclei [6 vocal control (VCN), 2 auditory (AN), and 2 hypothalamic (HN)] at four critical points during sexual differentiation of the VCN and the period of song learning, 25, 35, 55, and 90 days of age. Some birds were pretreated with α-methyl-para-tyrosine (αMPT) to allow estimation of NE and DA turnover rates. NE and DA levels in microdissected nuclei were quantified using high-performance liquid chromatography with electrochemical detection. αMPT treatment suppressed catecholamine synthesis just as effectively in juveniles as it does in adults and proved an effective method for estimating NE and DA turnover rates. Patterns of NE and DA function in most VCN and AN over development were quite different from those in HN in which NE and DA function changed gradually and showed no striking peaks. NE turnover rates changed significantly over development in all six VCN [nucleus interfacialis (Nlf), high vocal center (HVC), nucleus robustus of the archistriatum (RA), dorsomedial portion of the intercollicular nucleus (DM), Area X of the parolfactory lobe, and lateral portion of the magnocellular nucleus of the anterior neostriatum (IMAN)]; one AN [nucleus mesencephalicus lateralis pars dorsalis (MLd)], and one HN [preopticus anterior (POA)]. NE levels changed significantly in two VCN (Nlf and Area X). In Nlf, RA, Area X, IMAN, and MLd, NE levels and/or turnover rates showed a striking peak at day 25, which was not seen in HN. Both DA levels and turnover rates changed profoundly over development in 5 of 6 VCN (Nlf, RA, DM, Area X, and IMAN) and both AN (MLd and Field L). These nuclei showed striking peaks in DA levels and turnover rates, primarily on day 35 and/or 55, which then declined profoundly by day 90. This contrasted with the minimal change in DA turnover rates seen in one HN (POA) and the sixth VCN, HVC. In several VCN and AN, NE and DA levels and turnover rates during development reached levels never seen in adult males. Previous research has shown that catecholamine function is heightened in VCN during development compared to surrounding tissues. Our data demonstrate that NE and DA function during development shows pronounced peaks in most VCN not seen in HN. This is interesting because both VCN and HN are hormone sensitive, and both show hormone-modulated NE and DA function in adult males. The timing of these peaks suggests that increased catecholaminergic function may be involved in sexual differentiation of the VCN and song learning in finches. © 1998 John Wiley & Sons, Inc. J Neurobiol 34: 329–346, 1998     

Daily Fasting Improves Health and Survival in Male Mice Independent of Diet Composition and Calories

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The effect of dexamethasone on the occurrence and ultrastructure of rodlet cells in goldfish

In the bulbus arteriosus of goldfish Carassius auratus a subendothelial 'reticular space' was comprised of reticular-like cells, neutrophils, medium-sized granular leucocytes, phagocytes, endothelial cells and reticulo-endothelial cells; herein, rodlet cells (RCs) accumulated and probably matured. Four classes of RCs were identified: (1) Those occurring in the reticular space and contacting reticular-like cells; (2) those present in the reticular space contacting reticular-like and endothelial cells; here the RCs were discharging; (3) those occurring in the bulbar lumen anchored to lining endothelial cells or other RCs; (4) those free in the bulbar lumen. There was no significant difference in the number of RCs among control and saline- and dexamethasone-treated fish, but significant differences were found in RCs' class partition and in their discharge modality. In dexamethasone-treated goldfish class (3) RCs were almost absent (2% v. 10% of the other experimental groups), moreover 35% of the RCs developed a 'bleb' discharge modality rather than the most typical 'koronenartigen konfiguration' which developed in the vast majority (90%) of the other experimental groups.     

Measurement of adrenolutin as an oxidation product of catecholamines in plasma

Using the reverse phase high-performance liquid chromatography (HPLC) with mobile phases composed of simple acids, we have developed an assay technique for the measurement of adrenolutin, one of the oxidation products of catecholamines, in rat plasma. Ion-pairing chromatography permits the separation and quantitation of plasma adrenolutin (M) in a linear manner. Sample preparation involved the precipitation of plasma proteins with perchloric acid and it is easier to handle a large number of samples at a time. However, we were unable to demonstrate the presence of adrenochrome, another oxidation product of catecholamines, in plasma since adrenochrome was rapidly destroyed in acid as well as in blood and was quickly changed, into adrenolutin. Adrenolutin peak in HPLC was confirmed by 1) the retention time; 2) co-injection of adrenolutin and; 3) the appearance of ³H-adrenolutin after injection of ³H-norepinephrine. Administration of different catecholamines as well as adrenochrome and adrenolutin in rats also increased the level of adrenolutin in plasma. Adrenolutin was found to be present in plasma in other species including dog, rabbit and pig. High level of adrenolutin, which may represent total concentration of aminolutin in plasma, suggests the presence of an efficient mechanism for the oxidation of catecholamines under in vivo conditions.     

Isozyme expression in F1 hybrids between carp and goldfish

Interspecific genetic differences in malate dehydrogenase (MDH), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and esterase (EST) isozymes in carp (Cyprinus carpio) and goldfish (Carassius auratus) were used to examine the allelic expressions in the hybrid between these species. A unique liver SOD and muscle LDH phenotype unambiguously identifies all presumed hybrid individuals. There was no evidence of F₂ or backcross phenotypes in hybrid individuals. Liver MDH and EST phenotypes in hybrids show a preferential expression of goldfish isozymes. Variation in the levels of carp liver MDH isozymes may result from the polymorphism of a regulatory mutation affecting isozyme expression, leading to gene silencing after duplication.This work was supported through NSERC (Canada) grants to James P. Bogart and John F. Leatherland.     

Ultrastructural study on pronuclear development in fertilized eggs from goldfish, Carassius auratus

The formation of male and female pronuclei in physiologically monospermic fertilized eggs of the goldfish, Carassius auratus , has been investigated with transmission electron microscopy. Ultrastructural observations show that at 26°C the transformation of the sperm nucleus takes place very quickly. The sperm nuclear envelope degenerates and is replaced by a large number of smooth surface vesicles 1 min post-insemination. Concomitantly, most of the condensed sperm chromatin is dispersed and is surrounded by vesicles. Dispersion of the chromatin is followed by the fusion of vesicles and the formation of a new bilaminar pronuclear envelope. Within 5–10 min post-insemination, a spheroid male pronucleus with intranuclear annulate lamellae is produced. The formation of a female pronucleus is slightly different to that of the male pronucleus. The dispersing chromatin of the egg is divided into many groups, most of which are surrounded by multilaminar envelopes 5 min post-insemination. An ellipsoid female pronucleus with a continuous bilaminar pronuclear envelope and intranuclear annulate lamellae is formed 15 min post-insemination. Subsequently, the two pronuclei migrate towards one another. When the fully developed male and female pronuclei are located in the center of the blastodisc, each changes itself into a saccular complex 25 min post-insemination.     

Diel variations in carbonate incorporation into otoliths in goldfish

When D-[¹⁴C-U]-glucose was administered intraperitoneally into goldfish Carassius amatus at 20° C and 12L: 12D (dark period 1800–0600 hours) at 0600, 1200, 1800, 2400 and 0600 hours on the following day, glucose was metabolized to release ¹⁴CO₂ and then it was incorporated into otoliths as carbonate. The rate of metabolic activity, judging from the ratio of inorganic to organic radiocarbon in plasma, was low during the dark period. Carbon incorporation into otoliths was also minimized during 1800–2400 h. When fish were exposed to ambient water containing NaH¹⁴CO₃, plasma radioactivity was lowest during 1800–2400 hours, during which time carbon incorporation into otoliths was lowest. Plasma total CO₂ levels markedly increased during the dark period. These results clearly indicate that carbonate formation in otoliths has a diel variation with a nadir lasting 6 h from 1800 to 2400 hours under the photoperiod used.     

Axonal transport of proteoglycans to the goldfish optic tectum

The study addressed the question of whether³⁵SO₄ labeled molecules that the have been delivered to the goldfish optic nerve terminals by rapid axonal transport include soluble proteoglycans. For analysis, tectal homogenates were subfractionated into a souluble fraction (soluble after centrifugation at 105,000g), a lysis fraction (soluble after treatment with hypotonic buffer followed by centrifugation at 105,000g) and a final 105,000g pellet fraction. The soluble fraction contained 25.7% of incorporated radioactivity and upon DEAE chromatographys was resolved into a fraction of sulfated glycoproteins eluting at 0–0.32 M NaCl and containing 39.5% of total soluble label and a fraction eluting at 0.32–0.60 M NaCl containing 53.9% of soluble label. This latter fraction was included on columns of Sepharose CL-6B with or without 4 M guanidine and after pronase digestion was found to have 51% of its radioactivity contained in the glycosaminoglycans (GAGs) heparan sulfate and chondroitin (4 or 6) sulfate in the ratio of 70% to 30%. Mobility of both intact proteoglycans and constituent GAGs on Sepharose CL-6B indicated a size distribution that is smaller than has been observed for proteoglycans and GAGs from cultured neuronal cell lines. Similar analysis of lysis fraction, containing 11.5% of incorporated³⁵SO₄, showed a mixture of heparan sulfate and chondroitin sulfate containing proteoglycans, apparent free heparan sulfate and few, if any, sulfated glycoproteins. Overall, the result support the hypothesis that soluble proteoglycans are among the molecules axonally transported in the visual system.     

Fasting heat production and metabolic BW in group-housed broilers

Fasting heat production (FHP) is used for characterizing the basal metabolic rate of animals and the corresponding maintenance energy requirements and in the calculation of net energy value of feeds. In broilers, the most recent FHP estimates were obtained in the 1980s in slow-growing and fatter birds than nowadays. The FHP values (n=73; six experiments) measured in 3 to 6-week-old modern lines of broilers weighing 0.6 to 2.8 kg and growing at 80 to 100 g/day were used to update these literature values. Each measurement was obtained in a group of fasting broilers (5 to 14 birds) kept in a respiration chamber for at least 24 h. The FHP estimate corresponds to the asymptotic heat production corrected for zero physical activity obtained by modeling the decrease in heat production during the fasting day. The compilation of these data indicates that FHP was linearly related to the BW^0.70 (in kg), which can be considered as the metabolic BW of modern broilers. The 0.70 exponent differs from the conventional value of 0.75 used for mature animals. The FHP per kg of BW^0.70 ranged between 410 and 460 kJ/day according to the experiment (P<0.01). An experiment conducted with a shorter duration of fasting (16 h) indicated that FHP values are higher than those obtained over at least 24 h of fasting. Our values are similar to those obtained previously on fatter and slow-growing birds, even though the comparison is difficult since measurement conditions and methodologies have changed during the last 30 years. The FHP values obtained in our trials represent a basis for energy nutrition of modern broilers.     

High-density lipoprotein remodeling affects the osmotic properties of plasma in goldfish under critical salinity

To investigate the stress response and physiological adaptations of goldfish (Carassius auratus) to critical salinity (CS) waters, we analyzed high-density lipoprotein (HDL) stoichiometry, stress markers (cortisol, glucose), and plasma osmotic properties (Na⁺, osmolality, water content) using ichthyology, biochemistry, and proteomics approaches. After 21 days of exposure to CS, plasma concentrations of cortisol, glucose, and Na⁺ increased, indicating stress. Total plasma osmolality (Osm_total) and osmolality generated by inorganic (Osm_inorg) and organic osmolytes (Osm_org) also increased, the latter by ~2%. We associated the increase of Osm_org with (1) increased metabolite concentration (glucose), (2) dissociation of HDL particles resulting in increased HDL number per unit plasma volume (~1.5–2-fold) and (3) increased HDL osmotic activity. HDL remodeling may be the reason for the redistribution of bound and free water in plasma, which may contribute to water retention in plasma and, at the same time, to hemodynamic disturbances under CS conditions. The study's findings suggest that HDL remodeling is an important mechanism for maintaining osmotic homeostasis in fish, which is consistent with current capillary exchange models in vertebrates.     

Rotational stimulation-related changes of the motor asymmetry in the goldfish

We studied changes in the motor asymmetry of the goldfish induced by single-session long-lasting vestibular stimulations (clockwise and counter clockwise rotations around the rostro-caudal body axis) and repetitive everyday short sessions of such stimulation (training); the latter mode led to the development of adaptation (resistance to fatigue). Rotational stimulation of different durations and directions elicited effects of different patterns and intensities. Such stimulation enhanced or, vice versa, smoothed the motor asymmetry in “dextral” and “ sinistral” fishes, up to full symmetry or even a change of the preferred turning direction. Adaptation to unilateral rotational stimulation allows an experimenter to selectively and gradually induce the resistivity of the left-or right-ward asymmetry to fatigue effects. Earlier, we found that the motor asymmetry in the goldfish, which is determined by the functional asymmetry of the brain, correlates with the morphological asymmetry of Mauthner neurons localized in the medulla in a mirror manner and playing a crucial role in the control of turnings in the course of locomotion (swimming). Experimental rotational stimulation-induced gradual modification of the motor asymmetry in the goldfish can serve as a physiological model for more detailed studies of the structural base of the functional brain asymmetry and some mechanisms of adaptation on the level of single neurons. Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 432–442, September–December, 2005.     

Susceptibility of carp, roach and goldfish to a Dermocystidium-like organism

A visceral form of a Dermocystidium -like organism was found at 13% prevalence in a carp and in 7·4% in a roach population from Greece. Successful experimental transmission was recorded only in carp. Pathology of the parasite in experimental fish and naturally infected fish was similar. ©1998 The Fisheries Society of the British Isles