Effects of subchronic exposure to waterborne cadmium on H-P-I axis hormones and related genes in rare minnows (Gobiocypris rarus).

The H (hypothalamic)-P (pituitary)-I (interrenal) axis is critical in the stress response and other activities of fish. To further investigate cadmium (Cd) toxicity on the H-P-I axis and to identify its potential regulatory genes in fish, the adult female rare minnows (Gobiocypris rarus) were exposed to subchronic (5weeks) levels of waterborne Cd in the present study. This kind of treatment caused dose-dependent decline in fish growth, with significance in the high dose group (100µg/L). Correspondingly, low dose (5-50µg/L) waterborne Cd disrupted the endocrine system of H-P-I axis just at the secretion level, while high dose Cd disrupted both the secretion and synthesis of cortisol and its downstream signals in rare minnows, revealed by the significantly upregulation and positive correlation of corticosteroidogenic genes including MC2R, StAR, CYP11A1, and CYP11B1 in the kidney (including the interrenal tissue) (P<0.05), and the significant alteration of Glcci1, Hsp90AA and Hsp90AB in the hepatopancreas, gill and intestine as well (P<0.05). The expression of Glcci1 was significantly decreased in hepatopancreas, gill and intestine of tested fish following treatment, and its positive correlation with GR (Glucocorticoid receptor) suggested its potential regulation on the cortisol and/or H-P-I axis in fish. The expression of FKBP5 in the intestine was positively and significantly correlated with that of Hsp90AA (P<0.05), and the Hsp90AB transcript in the hepatopancreas was positively correlated with that of Hsp90AA (P<0.05), which indicated that Hsp90AA and Hsp90AB were more likely to serve as cofactors of GR and FKBP5 in response to Cd exposure.

Stress in Atlantic salmon: response to unpredictable chronic stress.

Combinations of stressors occur regularly throughout an animal's life, especially in agriculture and aquaculture settings. If an animal fails to acclimate to these stressors, stress becomes chronic, and a condition of allostatic overload arises with negative results for animal welfare. In the current study, we describe effects of exposing Atlantic salmon parr to an unpredictable chronic stressor (UCS) paradigm for 3 weeks. The paradigm involves exposure of fish to seven unpredictable stressors three times a day. At the end of the trial, experimental and control fish were challenged with yet another novel stressor and sampled before and 1 h after that challenge. Plasma cortisol decreased steadily over time in stressed fish, indicative of exhaustion of the endocrine stress axis. This was confirmed by a lower cortisol response to the novel stressor at the end of the stress period in chronically stressed fish compared with the control group. In the preoptic area (POA) and pituitary gland, chronic stress resulted in decreased gene expression of 11ßhsd2, gr1 and gr2 in the POA and increased expression of those genes in the pituitary gland. POA crf expression and pituitary expression of pomcs and mr increased, whereas interrenal gene expression was unaffected. Exposure to the novel stressor had no effect on POA and interrenal gene expression. In the pituitary, crfr1, pomcs, 11ßhsd2, grs and mr were down-regulated. In summary, our results provide a novel overview of the dynamic changes that occur at every level of the hypothalamic-pituitary gland-interrenal gland (HPI) axis as a result of chronic stress in Atlantic salmon.

Metabolic response in liver and Brockmann bodies of rainbow trout to inhibition of lipolysis; possible involvement of the hypothalamus-pituitary-interrenal (HPI) axis.

We previously demonstrated in rainbow trout that the decrease in circulating levels of fatty acid (FA) induced by treating fish with SDZ WAG 994 (SDZ) induced a counter-regulatory response in which the activation of the hypothalamus-pituitary-interrenal (HPI, equivalent to mammalian hypothalamus-pituitary-adrenal) axis was likely involved. This activation, probably not related to the control of food intake through FA sensor systems but to the modulation of lipolysis in peripheral tissues, liver and Brockmann bodies (BB, the main site of pancreatic endocrine cells in fish), would target the restoration of FA levels in plasma. To assess this hypothesis, we lowered circulating FA levels by treating fish with SDZ alone, or SDZ in the presence of metyrapone (an inhibitor of cortisol synthesis). In liver, the changes observed were not compatible with a direct FA-sensing response but with a stress response, which allows us to suggest that the detection of a FA decrease in the hypothalamus elicits a counter-regulatory response in liver, resulting in an activation of lipolysis to restore FA levels in plasma. The activation of these metabolic changes in liver could be attributable to the activation of the HPI axis and/or to the action of sympathetic pathways. In contrast, in BB, changes in circulating FA levels induce changes in several parameters compatible with the function of FA-sensing systems informing about the decrease in circulating FA levels.

Melanocortin receptor subtypes in interrenal cells and corticotropic activity of α-melanocyte-stimulating hormones in barfin flounder, Verasper moseri.

The aim of this study was to characterize the pituitary-interrenal axis in barfin flounder, a flatfish. Adrenocorticotropic hormone (ACTH) and melanocortin 2 receptor (MC2R) have been shown to be indispensable substances in pituitary and interrenal cells for cortisol release, respectively. We previously identified ACTH in the pars distalis of the barfin flounder pituitary gland, and detected transcripts of Mc1r, Mc4r, and Mc5r in the head kidney wherein interrenal cells are located. We have now demonstrated the presence of MC2R, which is a specific receptor for ACTH, in interrenal cells by molecular cloning of Mc2r cDNA and in situ hybridization, and confirmation of the in vitro cortisol-releasing activity of ACTH. These results show the presence of a classical pituitary-interrenal axis in this fish. We also evaluated the role of α-melanocyte-stimulating hormone (α-MSH) and its related peptides. In situ hybridization was used to demonstrate the expression of Mc5r in interrenal cells; both desacetyl-α-MSH and diacetyl-α-MSH showed in vitro cortisol-releasing activities, while the activity of α-MSH was negligible. These findings indicate the presence of an additional pituitary-interrenal axis consisting of α-MSH-like peptides secreted from the neurointermediate lobe of the pituitary and MC5R in the interrenal cells. The cortisol-releasing activity of desacetyl-α-MSH and diacetyl-α-MSH, compared with the low activity of α-MSH, suggest a unique and specific functional role of these forms of MSH peptides. The interrenal co-expression of two subtypes of Mcrs may play a role in this specialization.

Melanocortins regulate the electric waveforms of gymnotiform electric fish.

The hypothalamic-pituitary-adrenal/interrenal axis couples serotonergic activity in the brain to the peripheral regulators of energy balance and response to stress. The regulation of peripheral systems occurs largely through the release of peptide hormones, especially the melanocortins (adrenocorticotropic hormone [ACTH] and alpha melanocyte stimulating hormone [alpha-MSH]), and beta-endorphin. Once in circulation, these peptides regulate a wide range of processes; alpha-MSH in particular regulates behaviors and physiologies with sexual and social functions. We investigated the role of the HPI and melanocortin peptides in regulation of electric social signals in the gymnotiform electric fish, Brachyhypopomus pinnicaudatus. We found that corticotropin releasing factor, thyrotropin-releasing hormone, and alpha-MSH, three peptide hormones of the HPI/HPA, increased electric signal waveform amplitude and duration when injected into free-swimming fish. A fourth peptide, a synthetic cyclic-alpha-MSH analog attenuated the normal circadian and socially-induced EOD enhancements in vivo. When applied to the electrogenic cells (electrocytes) in vitro, only alpha-MSH increased the amplitude and duration of the electrocyte discharge similar to the waveform enhancements seen in vivo. The cyclic-alpha-MSH analog had no effect on its own, but blocked or attenuated alpha-MSH-induced enhancements in the single-cell discharge parameters, demonstrating that this compound functions as a silent antagonist at the electrocyte. Overall, these results strongly suggest that the HPI regulates the EOD communication signal, and demonstrate that circulating melanocortin peptides enhance the electrocyte discharge waveform.

The corticotropin-releasing factor system as a mediator of the appetite-suppressing effects of stress in fish.

A characteristic feature of the behavioural response to intensely acute or chronic stressors is a reduction in appetite. In fish, as in other vertebrates, the corticotropin-releasing factor (CRF) system plays a key role in coordinating the neuroendocrine, autonomic, and behavioural responses to stress. The following review documents the evidence implicating the CRF system as a mediator of the appetite-suppressing effects of stress in fish. Central injections of CRF or the related peptide, urotensin I (UI), or pharmacological treatments or stressors that result in an increase in forebrain CRF and UI gene expression, can elicit dose-dependent reductions in food intake that are at least partially reversed by pre-treatment with a CRF receptor antagonist. In addition, the appetite suppressing effects of various environmental, pathological, physical, and social stressors are associated with elevated levels of forebrain CRF and UI gene expression and with an activation of the hypothalamic-pituitary-interrenal (HPI) stress axis. In contrast, although stressors can also be associated with an increase in caudal neurosecretory system CRF and UI gene expression and an endocrine role for CRF-related peptides has been suggested, the physiological effects of peripheral CRF-related peptides on the gastrointestinal system and in the regulation of appetite have not been investigated. Overall, while CRF and UI appear to participate in the stress-induced changes in feeding behaviour in fish, the role of other know components of the CRF system is not known. Moreover, the extent to which the anorexigenic effects of CRF-related peptides are mediated through the hypothalamic feeding center, the HPI axis and cortisol, or via actions on descending autonomic pathways remains to be investigated.

Intra-adrenal interactions in fish: catecholamine stimulated cortisol release in sea bass (Dicentrarchus labrax L.).

The effect of the catecholamines, adrenaline and noradrenaline, on sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus) interrenal cortisol production was studied in vitro using a dynamic superfusion system technique. Increasing concentrations of catecholamines (10(-6), 10(-8) and 10(-10) M) stimulated cortisol production in a dose-dependent manner, in sea bass only. The increase in cortisol production stimulated by adrenaline (10(-6) M) and noradrenaline (10(-6) M) was inhibited by sotalol (2 x 10(-5) M), but not by prazosin suggesting that catecholamines stimulate cortisol release through the beta-receptor subtype. To evaluate catecholamine-induced signal transduction in head kidney cells, measurements of cAMP production and [H3]myo-inositol incorporation were determined in head kidney cell suspensions. Adrenaline and noradrenaline (10(-6) M) increased cAMP production, but had no effect on total inositol phosphate accumulation. These results indicate that catecholamines released from the chromaffin cells within the interrenal tissue may act as a paracrine factor to stimulate interrenal steroidogenesis in the sea bass.

Are hsps suitable for indicating stressed states in fish?

In response to most stressors, fish will elicit a generalized physiological stress response, which involves the activation of the hypothalamic-pituitary-interrenal axis (HPI). As in other vertebrates, this generalized stress response comprises physiological responses that are common to a wide range of environmental, physical and biological stressors. Recently, several families of heat shock proteins (hsps) have been proposed as indicators of a generalized stress response at the cellular level. Recent findings that hsp levels, in various fish tissues, respond to a wide range of stressors have supported the use of these proteins as indicators of stressed states in fish. However, the cellular stress response can vary, for example, according to tissue, hsp family and type of stressor. This brief overview of these responses in fish asks the question of whether changes in levels and families of hsps can be used as a suitable indicator of stressed states in fish. By casting this question in the context of the well-established generalized physiological stress response in fish, we argue that the use of hsps as indicators of stressed states in fish in general is premature.

Ff1b is required for the development of steroidogenic component of the zebrafish interrenal organ.

The zebrafish ftz-f1 gene, ff1b, is activated in two cell clusters lateral to the midline in the trunk during late embryogenesis. These cell clusters coalesce to form a discrete organ at around 30 hpf, which then begins to acquire a steroidogenic identity as evidenced by the expression of the steroidogenic enzyme genes, cyp11a and 3beta-hsd. The migration of the cell clusters to the midline is impaired in zebrafish midline signaling mutants. Knockdown of Ff1b activity by antisense ff1b morpholino oligonucleotide (ff1bMO) leads to phenotypes that are consistent with impaired osmoregulation. Injection of ff1bMO was also shown to downregulate the expression of cyp11a and 3beta-hsd. Histological comparison of wild-type and ff1b morphants at various embryonic and juvenile stages revealed the absence of interrenal tissue development in ff1b morphants. The morphological defects of ff1b morphants could be mimicked by treatment with aminoglutethimide, an inhibitor of de novo steroid synthesis. Based on these data, we propose that ff1b is required for the development of the steroidogenic tissue of the interrenal organ.

Parallel early development of zebrafish interrenal glands and pronephros: differential control by wt1 and ff1b.

Steroids are synthesized mainly from the adrenal cortex. Adrenal deficiencies are often associated with problems related to its development, which is not fully understood. To better understand adrenocortical development, we studied zebrafish because of the ease of embryo manipulation. The adrenocortical equivalent in zebrafish is called the interrenal, because it is embedded in the kidney. We find that interrenal development parallels that of the embryonic kidney (pronephros). Primordial interrenal cells first appear as bilateral intermediate mesoderm expressing ff1b in a region ventral to the third somite. These cells then migrate toward the axial midline and fuse together. The pronephric primordia are wt1-expressing cells located next to the interrenal. They also migrate to the axial midline and fuse to become glomeruli at later developmental stages. Our gene knockdown experiments indicate that wt1 is required for its initial restricted expression in pronephric primordia, pronephric cell migration and fusion. wt1 also appears to be involved in interrenal development and ff1b expression. Similarly, ff1b is required for interrenal differentiation and activation of the differentiated gene, cyp11a1. Our results show that the zebrafish interrenal and pronephros are situated close together and go through parallel developmental processes but are governed by different signaling events.

Interrenal responses to high ambient temperature in soft-shelled turtle, Lissemys punctata punctata.

An exposure to ambient temperature of 25 degrees C had no perceptible effect on interrenal function but further increase of temperature to 35 degrees C caused nuclear hypertrophy with increase of nuclear diameter, RNA concentration, acid phosphatase and alkaline phosphatase activities, accompanied by quantitative depletions of cholesterol (free, esterified and total) and ascorbic acid levels in the interrenal gland of the soft-shelled turtle Lissemys p. punctata. Similar manifestations of stimulation, except in the nucleus, were marked after exposure to 38 degrees C, but the degree of response in respect of esterified and free cholesterol levels was higher at 38 degrees C than at 35 degrees C. Moreover, withdrawal of 38 degrees C temperature and subsequently maintaining at 25 degrees C for 15 days showed reverse manifestations to those of 35 degrees C/38 degrees C, leading to a tendency towards normalcy. It is suggested that high a ambient temperature of 35 degrees C significantly stimulates interrenal function of Lissemys turtles, but further increase of 38 degrees C does not cause further overall stimulation, and withdrawal of higher temperature (38 degrees C) shows a tendency towards normalcy. It is also suggested that (a) high ambient temperature causes thermal stress, (b) it is reversible and (c) it acts on interrenal activity presumably via CRF-ACTH-axis in turtles.

Diplodus sargus interrenal-pituitary response: chemical communication in stressed fish.

In the present study the response of white sea-bream (Diplodus sargus), used as experimental model, to different stocking densities was tested to assess whether the induced stress conditions were able to activate a chemical communication. Once a good recovery was evident, six days after capture and transportation, experiments started to evaluate eventual changes in cortisol plasma levels as well as in both plasma and pituitary alpha-melanocyte stimulating hormone (alpha-MSH) levels. These studies demonstrated that a low stocking density (2.5kg/1000L) is not deleterious for this species while a higher one (10kg/1000L) induces the activation of the hypothalamus-pituitary-interrenal axis (HPI). Thus, in these fish were evident both a significant increase of cortisol plasma levels and a significant decrease of alpha-MSH pituitary levels, while no significant changes were detected in alpha-MSH plasma concentrations. The most relevant result reported in this study, for the first time in marine species, is the presence of a chemical communication among stressed fish. It also should be noted that the data obtained from cortisol and alpha-MSH detections strongly indicate a gender specificity of this chemical signal.

Differences in behaviour between rainbow trout selected for high- and low-stress responsiveness.

Two F1 lines of rainbow trout Oncorhynchus mykiss, divergent for plasma cortisol responsiveness, were generated by individual selection for post-stress cortisol values within the F0 generation. Adult females of the F1 generation were transferred to rearing in social isolation in observation tanks. After 6 days, locomotor activity in high-responding (HR) and low-responding (LR) individuals was quantified as time spent moving during a 20 min observation period. Behavioural observations were repeated the next day with a smaller conspecific intruder present in each observation tank. Differential hypothalamus-pituitary-interrenal axis activity in the two lines was subsequently confirmed by a standardised confinement stress test, which resulted in significantly higher plasma cortisol concentrations in HR than LR fish. HR fish displayed higher levels of locomotor activity than LR fish in the presence of an intruder, but not when in isolation. Aggressive behaviour towards the intruder was not seen, suggesting either a state-dependent lack of territorial aggression, or chronic stress in the experimental fish. A significantly higher incidence of feed intake was seen in LR trout when held in observation tanks (40% versus 0% of the fish took food when in isolation), suggesting that these fish acclimated more successfully to the experimental conditions than HR fish did. These results suggest that selection for stress responsiveness in salmonid fish leads to behavioural alterations, which are of potential importance to the performance of these fish in aquaculture rearing operations.

Gonadotropins and sex hormones modulate interrenal function in soft-shelled turtle.

The aim of the current work was to investigate the role of gonadotropins and female sex hormones on interrenal activity in soft-shelled turtles, Lissemys punctata punctata. 1) FSH treatment (3 microg/100 g body wt daily for 10 days) caused interrenal hypertrophy with increased nuclear diameter, raises of acid phosphatase and alkaline phosphatase concentrations, and depletions of cholesterol (except the free fraction) and ascorbic acid levels from the interrenal gland. However, LH treatment (3 microg/100 g body wt daily for 10 days) failed to produce any perceptible change in the interrenal activity. The combined treatments of FSH and LH (3 microg each/100 gm body wt daily for 10 days) produced no further change beyond that of FSH alone. 2) Estrogen treatment with the low dose (25 microg/100 g body wt daily for 10 days) had no effect, but with higher doses (50 microg or 100 microg/100 gm body wt daily for 10 days) is caused interrenal stimulation by inducing the same manifestations to those of FSH. The degree of manifestations was higher with the higher dose (100 microg daily) than that of the moderate dose (50 microg daily). Progesterone treatment with the low dose (25 microg /100 g body wt daily for 10 days) had no significant effect, but with the moderate (50 microg daily) and higher (100 microg daily) doses suppressed interrenal activity by showing the reverse changes to those of estrogen. The degree of manifestations was higher with the higher dose than that of the moderate one. The combined treatments of estrogen and progesterone (100 microg each/100 g body wt daily for 10 days) caused interrenal stimulation but to a lesser extent than that of estrogen alone. The findings are briefly discussed.

The hypothalamic-pituitary-interrenal axis and the control of food intake in teleost fish.

Although environmental, social and physical stressors have been shown to inhibit food intake and feeding behavior in fish, little is known about the mechanisms that mediate the appetite-suppressing effects of stress. Since the hypothalamic-pituitary-interrenal (HPI) axis is activated in response to most forms of stress in fish, components of this axis may be involved in mediating the food intake reductions elicited by stress. Recent investigations into the brain regulation of food intake in fish have identified several signals with orexigenic and anorexigenic properties. Among these appetite-regulating signals are related neuropeptides that can activate the HPI axis, namely corticotropin-releasing factor (CRF) and urotensin I (UI). Central injections of CRF or UI, or treatments that result in an increase in hypothalamic CRF and UI gene expression, can elicit dose-dependent decreases in food intake that can be reversed by pre-treatment with a CRF-receptor antagonist. Evidence also suggests that cortisol, the end product of HPI activation in most fishes (i.e. Osteichthyes), may be involved in the regulation of food intake. Overall, while elements of the HPI axis may mediate some of the appetite-suppressing effects of stress, it is undetermined how either CRF-related peptides, cortisol, or other elements of the stress response interact with the complex circuitry of the hypothalamic feeding center.

Pituitary and interrenal function in gilthead sea bream (Sparus aurata L., Teleostei) after handling and confinement stress.

Dynamics of adrenocorticotropin (ACTH), alpha melanocyte-stimulating hormone (alpha-MSH), N-acetylated-beta-endorphin (N-ac-beta-END), cortisol, and growth hormone (GH) were investigated in gilthead sea bream (Sparus aurata) stressed by handling plus confinement. As indices of the secondary stress response, plasma levels of glucose, lactate, and plasma ions were monitored. Within 1 h, plasma cortisol and ACTH levels increased above the control values but GH levels decreased. Subsequently, at 24 h cortisol and ACTH levels had declined, but were still higher than in controls, whereas GH levels had recovered after 4 h. Regarding the melanotrope peptides, there were no differences in plasma levels of alpha-MSH and N-ac-beta-END, but pituitary stores of these peptides were severely depleted already after 1 h, as were ACTH stores. Pituitary contents of proopiomelanocortin (POMC)-derived hormones did not show significant differences from 72 h onward. Therefore, the results indicate that both handling and confinement affected the corticotropes of the pars distalis and the melanotropes of the neurointermediate lobe but at different magnitudes. The possible involvement of corticotropin-releasing hormone (CRH) in the regulation of pituitary POMC-producing cell types under these conditions was indicated by the in vitro dose-dependent effect of the peptide on release of ACTH, alpha-MSH, and N-ac-beta-END. The corticocotropes appeared more responsive, and approximately 10-fold more sensitive, to CRH compared with the melanotropes. The ACTH-releasing potency of 1 nM CRH was inhibited 75% following pretreatment of the whole pituitary gland with 400 nM of the CRH antagonist alpha-helical CRH(9-41).

Pituitary proopiomelanocortin-derived peptides and hypothalamus-pituitary-interrenal axis activity in gilthead sea bream (Sparus aurata) during prolonged crowding stress: differential regulation of adrenocorticotropin hormone and alpha-melanocyte-stimulating hormone release by corticotropin-releasing hormone and thyrotropin-releasing hormone.

Plasma levels of cortisol, growth hormone (GH), adrenocorticotropin hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), N-acetyl-beta-endorphin, in vitro ACTH-stimulated cortisol secretion, and in vitro corticotropin-releasing hormone (CRH)- and thyrotropin-releasing hormone (TRH)-stimulated ACTH and alpha-MSH secretion were investigated in gilthead sea bream exposed to high stocking density (30 kg m(-3)) for 23 days. Within 3 days after the onset of crowding, plasma levels of cortisol, ACTH, alpha-MSH, and N-acetyl-beta-endorphin were above control values. After 7 days, plasma parameters had returned to control levels, but at 23 days, cortisol, alpha-MSH, and N-acetyl-beta-endorphin levels were again elevated over controls, indicating a long-term activation of the melanotrope cells. In contrast, crowding stress elicited a prolonged reduction in plasma GH levels concomitant with the increased hypothalamus-pituitary-interrenal axis (HPI) activation. Crowding stress enhanced cortisol secretory activity of the unstimulated interrenal cells. However, interrenal tissue from crowded fish in vitro displayed an attenuated response to ACTH stimulation compared with tissue from control fish, indicating a desensitization of these cells to ACTH during crowding. The involvement of pituitary proopiomelanocortin-derived peptides in the HPI axis of sea bream is indicated by the observed modulation of the CRH and TRH responsiveness of the corticotropes and melanotropes in crowded fish. At day 1, when there were crowding-induced plasma increases in ACTH and alpha-MSH, there was an attenuated CRH-stimulated but not TRH-stimulated, ACTH release. However, at that time, CRH- and TRH-induced responses of alpha-MSH secretion, and the unstimulated secretory activity of the MSH cells, were enhanced in crowded sea bream. These data provide evidence for stimulatory roles of multiple hypothalamic (CRH and TRH) and pituitary (ACTH and alpha-MSH) peptides in the activation of the hypothalamus-pituitary-interrenal axis under crowding conditions in sea bream.

Responsiveness of the hypothalamo-pituitary-interrenal axis in an amphibian (Bufo terrestris) exposed to coal combustion wastes.

To assess the responsiveness of the interrenal axis to stress, we injected toads exposed to coal combustion wastes and toads from an unpolluted reference site with adrenocorticotropic hormone (ACTH), as well as the vehicle alone (saline). Initial circulating levels of corticosterone in toads captured at the polluted area were significantly higher than levels in toads from the reference site. Corticosterone levels in toads from the polluted site remained high even after 2 weeks of laboratory acclimation and injection with saline. The results may suggest disruption of hepatic enzymes responsible for the metabolic clearance of steroid hormones. Injection of toads from the polluted site with ACTH had no effect on plasma corticosterone levels, whereas a similar treatment of toads from the reference site stimulated a marked increase in corticosterone. Our study provides evidence that toads exposed to coal combustion wastes may be less efficient at responding to additional environmental stressors.

[The direct activating effect of a nonapeptide neurohormone (vasotocin) on the thyroid and interrenal glands of sturgeons in in-vitro experiments]. / Neposredstvennoe aktiviruiushchee vliianie nonapeptidnogo neirogormona (vazototsina) na shchitovidnuiu i interrenalovuiu zhelezy osetrovykh ryb v opytakh in vitro.

An in-vitro effect of nonapeptide neurohormone vasotocin on thyroid and interrenal glands was studied in hybrid of Siberian and Lena sturgeons [correction of salmons] at light microscopy level using morphometric method. At a concentration of 0.1 and 1 nmol/l vasotocin was shown to exert undirectional stimulating effect on the thyroid and interrenal gland functions. In the presence of vasotocin at a concentration of 1 nmol/l in culture media the activity of glands is even more pronounced than under the influence of adenohypophyseal hormones, adrenocorticotropic (8 x 10 ng/ml) and thyrotropic (5 ng/ml).