Effect of mutations affecting coat color on the blood lymphocyte structure in the american mink (<Emphasis Type="Italic">Mustela vison</Emphasis> Schreber, 1777)

American minks with different genotypes containing the Aleutian coat color allele in the homozygous state, including the single recessive Aleutian (a/a); double recessive sapphire (a/a p/p) and lavender (m/m a/a); triple recessive violet (m/m a/a p/p); and dominant-recessive cross sapphire (S/+ a/a p/p), sapphire leopard (S ^K /+ a/a p/p), and shadow sapphire (S ^H /+ a/a p/p) minks, as well as American minks without the Aleutian allele, including the standard (+/+); single recessive silver-blue (p/p) and hedlund-white (h/h); double recessive pearl (k/k p/p), Finnish topaz (t ^S /t ^S b/b); incompletely dominant royal silver (S ^R /+), standard leopard (S ^K /+), and black crystal (C _R /+); and dominant-recessive snowy topaz (C _R /+ t ^S /t ^S b/b) and Kujtezhyspotted (S ^K /+ b/b) minks have been studied. Homozygosity for the a allele has been found to disturb the subcellular structure of leukocyte, namely the formation of abnormally large granules.     

Effect of mutations affecting coat color on the blood lymphocyte structure in the American mink (Mustela vison Schreber, 1777)

American minks with different genotypes containing the Aleutian coat color allele in the homozygous state, including the single recessive Aleutian (a/a); double recessive sapphire (a/a p/p) and lavender (m/m a/a); triple recessive violet (m/m a/a p/p); and dominant-recessive cross sapphire (S/+ a/a p/p), sapphire leopard (S(K)/+ a/a p/p), and shadow sapphire (S(H)/+ a/a p/p) minks, as well as American minks without the Aleutian allele, including the standard (+/+); single recessive silver-blue (p/p) and hedlund-white (h/h); double recessive pearl (k/k p/p), Finnish topaz (t(S)/t(S) b/b); incompletely dominant royal silver (S(R)/+), standard leopard (S(K)/+), and black crystal (C(R)/+); and dominant-recessive snowy topaz (C(R)/+ t(S)/t(S) b/b) and Kujtezhy-spotted (S(K)/+ b/b) minks have been studied. Homozygosity for the a allele has been found to disturb the subcellular structure of leukocyte, namely the formation of abnormally large granules.     

Concentration of monoamines in the brain of minks differing in their reaction to man

Content of dopamine in the striatum; of serotonin, 5-hydroxyindolacetic acid and noradrenaline in the hypothalamus, striatum and midbrain was studied in three groups of minks from population of an animal farm, differing by their reaction to humans (cowardly, calm, aggressive). The reaction to humans was estimated by a system of marks at the attempt to catch the mink with a mitten. Aggressive animals had a lowered level of serotonin in the hypothalamus and striatum, a lesser content of serotonin metabolite--5-hydroxyindolacetic acid in the striatum. Minks of different groups did not differ by noradrenaline content, but dopamine level in the striatum of cowardly minks was higher than in calm and aggressive animals. Conclusion is made that polymorphism of behaviour corresponds to polymorphism of the state of monoaminergic systems.     

Effects of drugs on brain neurotransmitter and pituitary-testicular function in male rats.

The effects of different drugs influencing brain neurotransmitter contents have been tested on the pituitary-testicular function in male rats. L-dopa (200 mg/kg body weight, i.p.) increased the dopamine and noradrenaline contents of the hypothalamus, amygdala, striatum and mesencephalon, but it was ineffective as regards the 5-hydroxytryptamine contents of the same brain areas, and increased the plasma testosterone level. alpha-Methyl-p-tyrosine (250 mg/kg b.w., i.p.) decreased the dopamine and noradrenaline contents of these brain areas, but it was ineffective to 5-hydroxytryptamine, and decreased the plasma testosterone level. Diethyldithiocarbamate (400 mg/kg b.w., i.p. twice a day) increased the dopamine levels in the hypothalamus, amygdala, striatum and mesencephalon, decreased the noradrenaline contents in the same brain regions but had no effect on the 5-hydroxytryptamine contents of these brain areas or on the testosterone level in the peripheral blood. p-Chlorophenylalanine (300 mg/kg b.w., i.p.) decreased the 5-hydroxytryptamine contents of the different brain areas, while it had no effect on the dopamine and noradrenaline levels or on the plasma testosterone level. 5-Hydroxytryptophan (200 mg/kg b.w., i.p.) increased the 5-hydroxytryptamine contents of all brain areas studied, but was without effect on the dopamine and noradrenaline contents or the plasma testosterone level. The data suggest that both dopamine and noradrenaline may be involved in the regulation of the pituitary-testicular function, and the ratio of the two transmitters might be more important that their actual levels in definite brain areas.     

EFFECTS OF AMINO-OXYACETIC ACID, ETHANOLAMINE-O-SULPHATE AND GABA ON THE CONTENTS OF GABA AND VARIOUS AMINES IN BRAIN SLICES

—The effects of amino-oxyacetic acid, ethanolamine-O-sulphate and γ-aminobutyric acid (GABA) on the contents of GABA, noradrenaline, dopamine and serotonin (5-HT) in slices of rat hypothalamus and midbrain were studied in vitro using a simultaneous fluorimetric assay procedure. Following control incubations the levels of 5-HT were raised, while the levels of the other substances remained steady. Amino-oxyacetic acid caused a reduction in the contents of noradrenaline and 5-HT, but had no effect on either GABA or dopamine. Ethanolamine-O-sulphate both raised the GABA content and lowered the noradrenaline content of slices, while the levels of dopamine and 5-HT were not altered. The presence of GABA in the incubation medium produced complex changes in these levels, depending both on the dose of GABA used and the brain area studied. In the hypothalamus, 0·07 mm -GABA caused an elevation in 5-HT, a drop in noradrenaline, and no change in either GABA or dopamine. With 5 mm -GABA, the noradrenaline level was raised slightly above control values and the endogenous GABA level doubled, while 5-HT and dopamine levels were not different from controls. Similar changes in 5-HT and GABA contents were observed with midbrain slices, but noradrenaline and dopamine were not affected. The possible modes of action of amino-oxyacetic acid and ethanolamine-O-sulphate on the amino acid and amine systems in the brain are discussed.     

Effects of L-Tryptophan on Indoleamines and Catecholamines in Discrete Brain Regions of Wild Type and Lurcher Mutant Mice

The biochemical parameters of the serotoninergic system were examined in wild type mice and Lurcher mutants after chronic treatment (40 days) with the serotonin (5-HT) precursor L-tryptophan (50 mg/kg; i.p.). Tissue contents in 5-HT, dopamine and noradrenaline, as well as some of their metabolites, were measured in frontal cortex, neostriatum, thalamus, brainstem, cerebellum and spinal cord by high-performance liquid chromatography. The tissue levels were used as a biochemical index of the function of the monoamine innervations in this animal model of cerebellar ataxia. The results show that Lurcher mutants retain higher concentrations of L-tryptophan and total indoleamines, but that 5-HT is probably stored in a non-releasable compartment. In the particular case of the hypoplastic cerebellum, the reorganization of 5-HT nerve terminals leads to an accrued indoleamine synthesis, indicating that the Lurcher mutants can accumulate 5-HT, but do not utilize it efficiently in synaptic transmission.     

Dose-related effects of cysteamine treatment on hypothalamic and striatal dopamine, noradrenaline and serotonin neurotransmission

The dose-related effects of cysteamine treatment on hypothalamic and striatal neurotransmission were investigated. Cysteamine pretreatment with a dose of 150 mg/kg slightly increased the dopamine, and markedly decreased the noradrenaline, content of the hypothalamus in a dose-related manner. The serotonin levels of the hypothalamus and striatum were not affected. Cysteamine pretreatment with a higher dose (300 mg/kg sc) slightly increased the uptake of noradrenaline into hypothalamic slices. The drug did not influence dopamine and serotonin uptake into hypothalamus and striatal slices. These results suggest that cysteamine decreases rather selectively the noradrenaline content of the hypothalamus.     

Interplay between aggression,brain monoamines and fur color mutation in the American mink

Domestication of wild animals alters the aggression towards humans, brain monoamines and coat pigmentation. Our aim is the interplay between aggression, brain monoamines and depigmentation. The Hedlund white mutation in the American mink is an extreme case of depigmentation observed in domesticated animals. The aggressive (?2.06 ± 0.03) and tame (+3.5 ± 0.1) populations of wild‐type dark brown color (standard) minks were bred during 17 successive generations for aggressive or tame reaction towards humans, respectively. The Hedlund mutation was transferred to the aggressive and tame backgrounds to generate aggressive (?1.2 ± 0.1) and tame (+3.0 ± 0.2) Hedlund minks. Four groups of 10 males with equal expression of aggressive (?2) or tame (+5) behavior, standard or with the Hedlund mutation, were selected to study biogenic amines in the brain. Decreased levels of noradrenaline in the hypothalamus, but increased concentrations of the serotonin metabolite, 5‐hydroxyindoleacetic acid and dopamine metabolite, homovanillic acid, in the striatum were measured in the tame compared with the aggressive standard minks. The Hedlund mutation increased noradrenaline level in the hypothalamus and substantia nigra, serotonin level in the substantia nigra and striatum and decreased dopamine concentration in the hypothalamus and striatum. Significant interaction effects were found between the Hedlund mutation and aggressive behavior on serotonin metabolism in the substantia nigra (P < 0.001), dopamine level in the midbrain (P < 0.01) and its metabolism in the striatum (P < 0.05). These results provide the first experimental evidence of the interplay between aggression, brain monoamines and the Hedlund mutation in the American minks.     

A candidate gene approach identifies variants in SLC45A2 that explain dilute phenotypes,pearl and sunshine,in compound heterozygote horses

Variations in the SLC45A2 gene are responsible for the dilution phenotypes cream and pearl in domestic horses. Cream dilution is inherited in an incomplete dominant manner, diluting only red in the heterozygous state but both red and black pigments when two alleles are present. The pearl dilution is recessive and dilutes only the red and black pigment in the homozygous state or when paired with a cream allele. Horses that inherit one copy of pearl (C^prl) and one copy of the dominant cream allele (C^Cr) display a dilution phenotype similar to that of homozygous cream, suggesting that pearl is the result of a different variation in the same gene responsible for cream. We sequenced SLC45A2 in two ‘false double dilute’ horses that appeared phenotypically homozygous cream but tested as possessing only a single C^Cr allele. We also sequenced one known pearl carrier to screen for putative causal variants. The missense variant ECA21:SLC45A2:c.985G>A; p.Ala329Thr (C^prl) was present in one false double dilute and the pearl carrier and was also genotyped in an additional 126 horses for statistical evaluation. The genotype matched the expected phenotype in all horses (P‐value = 6.5 × 10^?41) and is identical to a pearl variant found previously. The second false double dilute horse and one non‐dilute offspring genotyped as heterozygous for a novel missense variant ECA21:SLC45A2:c.568G>A (p.Gly190Arg), the proposed C^sun variant (for the name of the horse). This variant produces a recessive dilution similar to pearl and indicates that multiple alleles of SLC45A2 result in dilution phenotypes in the domestic horse.     

The effect of medial forebrain bundle lesion on thyrotropin secretion in the rat

The medial forebrain bundle (MFB) was partially lesioned with 6-hydroxydopamine (6-OHDA) in order to investigate the effect of deficient central noradrenergic regulation on thyrotropin (TSH) secretion in the rat. 6-OHDA injection into the MFB significantly reduced the noradrenaline (NA), dopamine (DA) and serotonin (5-HT) content of the whole hypothalamus. NA and 5-HT concentrations were also significantly decreased in the paraventricular nucleus (PVN). The MFB lesion did not affect the clonidine (250 g/kg, i.p.) induced stimulation of TSH release or the isoproterenol (1 mg/kg i.p.) induced decrease in TSH levels. Thyrotropin releasing hormone (TRH, 5 g/kg i.v.) caused a similar significant stimulation of TSH secretion in lesioned and non-lesioned rats. The present results do not support the hypothesis that the blunted TSH response to TRH observed in depressed patients results from a deficiency in noradrenergic neurotransmission.     

Distribution and function of biogenic amines in the heart of <Emphasis Type="Italic">Nautilus pompilius</Emphasis> L. (Cephalopoda,Tetrabranchiata)

Summary Biogenic amines (serotonin and catecholamines), play an important role in the control of the blood flow not only in vertebrates, but also in invertebrates such as cephalopods. In contrast to the well investigated hearts of the ȁ8modern,ȁ9 coleoid cephalopods, the innervation of the heart of the archaic Nautilus pompilius L. has not been studied in detail. In this study the distribution and effects of biogenic amines in the Nautilus heart were investigated. Serotonin and catecholamines were visualised by the glyxoylic acid induced fluorescence. High performance liquid chromatotography analysis was performed to discriminate between the catecholamines, which showed a high content of noradrenaline in the 4 auricles, the aorta and the ventricle, whereas the ventricle showed a high dopamine content. Adrenaline was found at a very low concentration in the ventricle. Serotonin and dopamine were also immunohistochemically localised to larger nerves and throughout the heart, respectively. In organ bath experiments, the auricles showed little spontaneous activity. After adding serotonin, they displayed rhythmical contractions, which were accelerated dose-dependently by noradrenaline. In summary, these data suggest an important role for biogenic amines in the control of the heart of Nautilus pompilius L., with serotonin possibly stimulating excitatory nerve fibres, whereas noradrenaline is likely to influence the muscle contraction itself.     

Catecholamines in Regulation of Development of GnRH Neurons of Rat Fetuses

The contents of dopamine, serotonin, and noradrenaline in rat fetuses developing under the conditions of their deficiency induced by administration of α-methyl-para-tyrosine to females during 11th to 16th or 20th day of pregnancy and in fetuses, whose mothers were given saline at the same time, were determined using HPLC with subsequent electrochemical detection. Administration of α-methyl-para-tyrosine led to decreased levels of dopamine and noradrenaline in the areas of migration of GnRH-neurons in fetuses on days 17 and 21 of prenatal development. The concentration of serotonin remained unchanged, except in the head nasal area in males on day 21. The areas of interaction between the brain catecholaminergic systems and migrating and differentiating GnRH-neurons were determined by double immunohistochemical labeling. Close topographical location of GnRH-immunoreactive neurons and tyrosine hydroxylase-immunoreactive in the area of nucleus accumbens on days 17 and 20, as well as in the median eminence on day 20. The GnRH concentration in the caudal areas of migration of GnRH-neurons under the normal conditions and in the case of catecholamine deficiency was determined using radioimmunoassay. After administration of α-methyl-para-tyrosine the GnRH concentration in the anterior hypothalamus decreased in females. The data obtained suggest the involvement of catecholamines in the regulation of development of GnRH-Neurons during prenatal development. In addition, the adequacy and efficiency of the used model of catecholamine deficiency for studying the development of such neurons was confirmed.     

Control of peptide release from cells of the intermediate lobe of the rat pituitary

Summary When rats were injected with 6-hydroxydopamine the catecholaminergic nerve terminals in their intermediate lobes exhibited distinct signs of degeneration. Morphometric examination of the Golgi apparatus in cells of the intermediate lobe of these rats showed significant enlargement of Golgi cisternae. The release of adrenocorticotropin, -endorphin/lipotropin and -melanotropin from intermediate-lobe cells in vitro was measured by radioimmunoassay. The high basal peptide release was inhibited by dopamine and stimulated by methyl-isobutyl-xanthine. In contrast, -aminobutyric acid, serotonin, histamine and noradrenaline, or corticotropin-releasing hormone, rat hypothalamic extract and vasopressin had no or only very weak effects. These observations indicate that the synthetic apparatus of intermediate-lobe cells is constantly depressed by dopaminergic nerves. We were not able to stimulate peptide release from intermediate-lobe cells by use of the abovementioned endogenous agents.Supported by Deutsche Forschungsgemeinschaft: Ausbildungsstipendium Sto 162 (G.S.), SFB 87/B2, and Heisenberg Stipendium (K.H.V.)     

The cytochrome P450 2D‐mediated formation of serotonin from 5‐methoxytryptamine in the brain in vivo: a microdialysis study

The cytochrome P450 2D (CYP2D) mediates synthesis of serotonin from 5‐methoxytryptamine (5‐MT), shown in vitro for cDNA‐expressed CYP2D‐isoforms and liver and brain microsomes. We aimed to demonstrate this synthesis in the brain in vivo. We measured serotonin tissue content in brain regions after 5‐MT injection into the raphe nuclei (Model‐A), and its extracellular concentration in rat frontal cortex and striatum using an in vivo microdialysis (Model‐B) in male Wistar rats. Naïve rats served as control animals. 5‐MT injection into the raphe nuclei of PCPA‐(tryptophan hydroxylase inhibitor)‐pretreated rats increased the tissue concentration of serotonin (from 40 to 90% of the control value, respectively, in the striatum), while the CYP2D inhibitor quinine diminished serotonin level in some brain structures of those animals (Model‐A). 5‐MT given locally through a microdialysis probe markedly increased extracellular serotonin concentration in the frontal cortex and striatum (to 800 and 1000% of the basal level, respectively) and changed dopamine concentration (Model‐B). Quinine alone had no effect on serotonin concentration; however, given jointly with 5‐MT, it prevented the 5‐MT‐induced increase in cortical serotonin in naïve rats and in striatal serotonin in PCPA‐treated animals. These results indicate that the CYP2D‐catalyzed alternative pathway of serotonin synthesis from 5‐MT is relevant in the brain in vivo, and set a new target for the action of psychotropics.

     

Effects of acute and prolonged naphthalene exposure on brain monoaminergic neurotransmitters in rainbow trout (Oncorhynchus mykiss)

We have shown previously that acute (1 to 6 h) and prolonged (1 to 5 days) exposure of rainbow trout to naphthalene resulted in decreased plasmatic cortisol and 17-beta-estradiol levels. In order to elucidate the mechanisms through which naphthalene might disrupt endocrine regulation, the present study investigated whether brain monoaminergic neurotransmitters are altered by the action of this polycyclic aromatic hydrocarbon. In a first experiment, immature rainbow trout were injected with vegetable oil alone or containing naphthalene (10 and 50 mg/kg, i.p.), and sacrificed 1, 3 and 6 h after treatment. In a second experiment, slow-coconut oil implants alone or containing naphthalene (doses of 10 and 50 mg/kg) were i.p. located and fish sacrificed 1, 3 and 5 days after treatment. Levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and noradrenaline (NA) were measured in several brain regions by HPLC. The results show that short-term naphthalene increases DA and 5-HT contents in hypothalamus and telencephalon, but differentially alter contents of the acid metabolites. Implants with naphthalene reduced DA content in hypothalamus and preoptic region but increased in telencephalon. 5-HT metabolism was decreased in hypothalamus, preoptic region, pituitary and brain stem after 3 to 6 days of treatment. In addition, the levels of NA were increased in hypothalamus and telencephalon after acute treatment and in hypothalamus and preoptic area after several days of exposure to naphthalene. These data suggest that brain neurotransmitter systems are sensitive to polycyclic aromatic hydrocarbons and could represent a target of the naphthalene-induced neuroendocrine disruption.     

Hormonal status in different phenotypic forms of Black Sea trout <Emphasis Type="Italic">Salmo trutta labrax</Emphasis>

In three phenotypic forms (parrs, trout form, and kumzha form) of fish-farm Black Sea trout (age 1+) and wild Black Sea trout (age 1+ and 2+), Salmo trutta labrax, inhabiting the basin of the Mzymta River, the content of monoamines (dopamine, noradrenalin, and serotonin) and of their metabolites (3,4-dihydroxyindolacetic acid, 3-methoxy-4-hydroxyphenyl glycol, and 5-hydroxyindolacetic acid) was investigated in brain regions (forebrain, optic tectum, brainstem, hypothalamus, and hypophysis) and the level of cortisol, thyroxin, triiodothyronine, growth hormone, and adrenocorticotropic hormone was investigated in blood. Data on length and weight of fish body and maturation stage of gonads are indicated. The hormonal level differs in the fish of different phenotypic forms. It is the highest in specimens of the kumzha form which completed parr-smolt transformation. Among wild fish, numerous mature females at age 1+ were found which indicated the presence of a dwarf form of the Black Sea trout in the Caucasus in the Mzymta River.     

Monoamines and reproduction in Pecten maximus,a preliminary approach

Summary

The distribution of serotonin-like immunoreactivity was studied in the central nervous system and the gonad of Pecten maximus. Cerebral and pedal ganglia contain a well developed serotonin-immunoreactive neuronal subpopulation, whereas positive neurons are scarce in the visceral ganglion. The distribution pattern of immunoreactive elements in the gonad indicate that serotonin is involved in peripheral neurotransmission of this organ. Seasonal variations of monoamines (serotonin, dopamine and noradrenaline) have been investigated in the nervous system using HPLC. Lower concentrations of serotonin are observed during winter in the central nervous system; dopamine levels of the visceral ganglion are correlated to gonadal growth.     

Neonatal 6-hydroxydopamine treatment: noradrenaline levels and in vitro 3Hcatecholamine synthesis in discrete brain regions of adult rats

Endogenous noradrenaline levels are elevated in medulla oblongata, mesencephalon, pons and thalamus of adult rats which had been treated with 6-hydroxydopamine on days 1, 2, 8 and 15 after birth. Levels in spinal cord, cerebellum, hippocampus/amygdala and cortex are depressed, whereas no significant changes are observed in striatum, hypothalamus and medulla spinalis. The rate at which medulla oblongata synthesizes tritiated noradrenaline and dopamine from tritiated tyrosine $\text{in}$$\text{vitro}$ is markedly enhanced. No effect was apparent on catecholamine synthesis in hypothalamus. Tritiated noradrenaline synthesis, but not tritiated dopamine synthesis, in the cortex is depressed. These results support the view that neonatal 6-hydroxydopamine treatment causes a degeneration of noradrenaline nerve terminals in the cortex and induces an increase in noradrenaline terminals in the medulla oblongata.     

Effect of monoamine receptor agonists and antagonists on cyclic AMP accumulation in human cerebral cortex slices.

In human cerebral cortex slices noradrenaline, isoproterenol (a beta-adrenergic agonist), dopamine, apomorphine (a dopaminergic agonist), and serotonin stimulated cyclic AMP formation: noradrenaline greater than or equal to isoproterenol greater than dopamine = apomorphine = serotonin. Clonidine (and alpha-adrenergic agonist) was ineffective in stimulating cyclic AMP formation in temporal cortex slices. The stimulatory effect of noradrenaline and isoproterenol was blocked by propranolol (a beta-adrenergic blocker) but not by phentolamine (an alpha-adrenergic blocker). Pimozide (a selective dopaminergic antagonist) inhibited the increase of cyclic AMP formation induced by dopamine or apomorphine but not that induced by noradrenaline, isoproterenol, or serotonin. Neither propranolol or phentolamine had any effect on dopamine- or serotonin-stimulated cyclic AMP formation. Chlorpromazine blocked the increase of cyclic AMP formation induced by noradrenaline, dopamine or serotonin, while cyproheptadine, a putative central serotonergic antagonist, was ineffective. These observations suggest that there may be at least two monoamine-sensitive adenylate cyclases in human cerebral cortex which have the characteristics of a beta-adrenergic and a dopaminergic receptor, respectively, and also possibly a serotonergic receptor.     

N-Benzyl-N-(pyrrolidin-3-yl)carboxamides as a new class of selective dual serotonin/noradrenaline reuptake inhibitors

The structure–activity relationship and the synthesis of novel N-benzyl-N-(pyrrolidin-3-yl)carboxamides as dual serotonin (5-HT) and noradrenaline (NA) monoamine reuptake inhibitors are described. Compounds such as 18 exhibited dual 5-HT and NA reuptake inhibition, good selectivity over dopamine (DA) reuptake inhibition and drug-like physicochemical properties consistent with CNS target space. Compound 18 was selected for further preclinical evaluation.