Hypothalamo-hypophysial Neurosecretory System Research Articles

A complete study of neuroendocrine regulation of fish reproduction. 4. Migration impulse as a starting mechanism of spawning

The participation of the hypothalamo-hypophysial neurosecretory system (NS) in the initiation of anadromous fish spawning migration was established on the basis of ecological-histophysiological analysis the results of histomorphological, immunohistochemical and electron microscopic studies for the first time. Activation of the neurosecretory products synthesis in the neurosecretory cells perikaryons and their excretion into the cerebrospinal fluid of the III brain ventricle in anadromous migrants forms at the beginning of the river spawning migration, spring-spawning: Russian sturgeon, stellate sturgeon and autumn-spawning: pink salmon and chum salmon, was shown. Transport and mass accumulation of neurosecretory products in the neurohypophysis were discovered at the same time. It is concluded, that the NS impacts a complex synchronous effect, which consists: firstly, in the neurotropic effect of nonapeptide neurohormones (NPh) on behavioral centers, which causes a dominant state of CNS excitation corresponding to the “Migration impulse”; secondly, in the violation of the long-term adapted marine “Pastured” level of osmoregulation; and thirdly, in the cessation of the well-known antigonadotropic effect of NPh, which contributes the organism transition to the energyconsuming energy type of metabolism. A comparative analysis (cross-analysis) of our own and literature data confirms the commonality and points to the universality of this metabolic mechanism for different forms of migration in fish ontogeny, which allows us to consider it as the most important aromorphosis type of phylogenetic adaptations, aimed at the species biological progress achieving. In the subsequent navigational mechanisms of homing, widely covered in the world literature, the leading role is played by the luliberinergic centers of the hypothalamus. The ecological diversity of these population-level mechanisms and the presence of straing in fish allow us to consider them as specializations of microevolutionary origin. The most promising direction for the further neuroendocrinological research development seems to be the analysis of the mechanisms of imprinting in connection with the enhancement of growth and survival of juveniles in the critical salinity medium, and for the purpose of homing control (development of the commercial fish-return biotechnology management) — the mechanisms of interaction between the NS and the luliberinergic centers in the neuroendocrine complex of CNS.

A full-system study of neuroendocrine regulation of fish reproduction

The participation of the hypothalamo-hypophysial neurosecretory system (HHNS) in the initiation of energy-consuming migration and spawning behaviors and the completion of spawning by suppressing the hyperactivity of the target glands, which ensures the body transition to energy-saving plastic metabolism was established by ecological-histophysiological full-system studies. The analysis of the HHNS key role in these processes made it possible to develop a constructive working scheme for the neuroendocrine integration of fish reproduction on the principle of self-regulation. In order to increase the fish factory reproduction biotech efficiency new methods for controlling of its biotechnology have been developed on this basis. The technology of preparation and the results of industrial tests of the effectiveness pituitary preparations developed to enhance fish maturation: isolated anterior and posterior pituitary lobes (APL and PPL) of the pituitary gland are presented in this part of the research. The increase degree of the of fish farming producers use average of 15% was proved by production (industrial) tests of the effectiveness of the use of the drug APL at sturgeon fish breeding plants of the lower rivers Volga and Don. To increase the effectiveness of the drug APL usage, its dependence on the degree of preparedness of females for puberty and ovulation was established by the most objective assessment of their individual fish-breeding qualities by the degree of the oocyte nucleus polarization. The most important indicators of the producers physiological state and offspring are stored after the use of APL not only within the production norm, but also qualitatively exceed the “control” — the whole pituitary gland. In order to avoid significant production loss of pituitary dry matter (especially when removing PPL) and the high consumption (35–40%) of the pituitary glands to stimulate the maturation of fish males a “Method for stimulating puberty of male fish” by the isolated posterior pituitary lobe was developed, providing waste-free technology for the preparation and usage of both drugs. Possible prospects for improving methods of stimulating sexual maturity of fish breeders are discussed.

A full-system study of neuroendocrine regulation of fish reproduction. 1. Development biotech management principles of artificial fish reproduction on the basis of the ecologo-histophysiological scientific approach

A completed full-system (scientific-applied) ecological-histophysiological study of the hypothalamo-hypophysial neurosecretory system (HHNS) participation in fish reproduction was established. With the help of light-, electron-microscopy and immunocytochemistry it is established for the first time that at the beginning migrations of passing fish there is a mass accumulation of neurosecretory products in neurohypophysis, which indicates to the inhibition of the normal level of their excretion into the bloodstream. At the same time, they are actively synthesized in the pericarions of the neurosecretory cells in the preoptic nucleus and excretioned into the cavity of the III brain ventricle. Firstly it is a sign of a violation of their basic osmoregulatory function, which should cause a change in habitat. Secondly, the synchronous excretion of neurohormones into the brain’s liquor should cause their neurotropic effect on the CNS behavior centers in the form of a dominant state of arousal in the form of “migration impulse”. At the beginning of spawning, regardless of its season, HHNS also initiates spawning behavior and completes spawning by participating in the body’s protective-adaptive reactions to natural physiological stress. The functional role of the HHNS in fish reproduction is to initiate energy-intensive reproductive processes of migratory and spawning behaviors, and to complete spawning by suppressing the hyperactivity of the target glands, which ensures the body’s transition to energy-saving plastic exchange. The analysis of this key role of HHNS in the integration of fish reproduction by the principle of self-regulation has allowed to define the principles of effective reproduction and cultivation fish management, primarily in the form of finding the most effective impacts on the centers of integration of managed functions or modeling their effects, which should be carried out in natural periods of functional lability of the body. A constructive working scheme neuroendocrine integration of fish reproduction has been presented and the possibility of applying method of comparative analysis to further develop the system management biotechnics of fish populations reproduction is considered.

The development system of biotech management of reproduction fish populations based on neuroendocrinological research

The participation of the hypothalamo-hypophysial neurosecretory system (HHNS) in fish reproduction was established by ecologo-histophysiological research with the help of light-, electronmicroscopy and immunocytochemistry. At the beginning of migrations of passing fish an active synthesis of neurosecretory products in pericarions of neurosecretory cells and their excretion into the cavity of the III brain ventricle was stated, while a mass accumulation of them in neurohypophysis occurs. Firstly, the excretion of neurohormones into the brain’s liquor should cause their neurotropic effect on the CNS behavior centers in the form of a dominant state of arousal, designated as “migration impulse”. Then HHNS initiates spawning behavior at the beginning of spawning and completes it by participating in overcoming natural physiological stress. In fish reproduction the main functional role of HHNS is to initiate reproductive energy-intensive processes of migratory and spawning behaviors, and to completion spawning by suppressing the hyperactivity of the target glands, ensuring the body’s transition to energysaving plastic metabolic exchange. The analysis of the key role of HHNS in fish reproduction has allowed to present a constructive working scheme of its neuroendocrine integration by the principle of self-regulation and to develop, on this basis, the system management of biotech reproduction of fish populations.

Функциональная роль гипоталамо- гипофизарной нейросекреторной системы в миграциях и нересте рыб

The results of the ecological-histophysiological study of the hypothalamo-hypophysial neurosecretory system (HHNS) by use of light- and electron-microscopical morphometric methods and comparative analysis of the results are presented. At the beginning of migrations a state of “HHNS mobilization” has been established. It is expressed in the form of the strong synthesis activation of neurosecretary products in neurosecretory cells (NSC) and their transport in dendrites and axons to neurohypophysis (NH), where, their mass accumulation, however, occurs. This completion of moderate “normal” level of excretion of nonapeptide neurohormones (NP-NH) into the bloodstream disrupts the body’s water-salt homeostasis. The synchronized transventricular direction of the NP-NH excretion from dendrites and axons into the brain liquor of III ventricle provides their neurotropic effect in the behavioral centers of Central Nervous System (CNS). As a result, HHNS has a decisive double synchronous effect, which disrupts the long-adapted “pasture” type of osmoregulation (hyper- or hypoosmotic), which is probably the main physiological stimulus of habitat change and, at the same time, it includes the behavioral centers of the CNS, which causes a dominant state, originally defined as a “migration impulse.”The interactions of nonapeptide- and luliberinergic centers of the hypothalamus in the navigational mechanisms of homing and imprinting are discussed. At the beginning of spawning, regardless of its season a strong activation of HHNS, followed by a decrease in its functional activity, was discovered in fish of continuous spawning. The detected two-phase reaction of the HHNS seems to be a reflection of its participation in the body’s protective and adaptive responses to physiological stress. The key role of the HHNS in integrating migration and spawning processes is discussed.

Ecologic-histophysiological overview of the involvement of the hypothalamo-hypophysial neurosecretory system in fish reproduction

The participation of the hypothalamo-hypophysial neurosecretory system (HHNS) in fish reproduction was shown by histomorphological and electronic microscopical studies with the use of quantitative morphometry. The activation of HHNS at the beginning of spawning and the following decrease of its functional activity was revealed in all studied one-time spawning fish species independently of the spawning season (based on spring-, autumn- and winter-spawning genera: Acipenser, Oncorhynchus, and Lota respectively). The diphasic reaction of HHNS corresponding to stages of “an alarm and resistance to stress”, is considered to be the reflection of its participation in protective-adaptive reactions of an organism to a physiological stress. In monocyclic species, right after spawning, there becomes the blockade of neurohormone releasing function from neurohypophysis corresponding to supernatural inhibition of system at disstress. At the beginning of spawning nonapeptide neurohormones (NpNh) of HHNS initiate spawning behavior and the appearance of “mating attire” by exposure to the central nervous system, pituitary gland and complex visceral organs. Then they promote ovulation and spermiation by stimulating the contraction of the smooth muscles of gonad. By the end of reproduction, they participate in the implementation of the body’s adaptations, aimed at overcoming physiological stress-spawning. Maintaining the body’s metabolic equilibrium is ensured by the pronounced anti-gonadotropic NpNh effect by inhibiting the gonadoliberin secretion and stimulating at the same time its antagonist – adrenocorticotropin secretion, as well as their direct effect on endocrine and generative gonad’s functions. This effect is crucial for the normalization of the physiological body state after spawning, as it allows to radically affect the nature of metabolic processes, by “switching” them from generative to plastic metabolism. A constructive working scheme of neuroendocrine regulation fish reproduction – its initiation (stimulating neurohormonal effect) and completion (inhibitory effect) by the self-regulation principle is presented. The important HHNS functional role in the integration of fish reproduction and the intended mechanisms for its participation in spawning migrations are discussed.

Cyclic Changes In The Hypothalamo Neurohypophysial System of Xenentodon Cancila (HAM.)

The presence of functional hypothalamo-hypophysial neurosecretory system in vertebrates has led to revise earlier views regarding the hypothalamus-pituitary relationship. The hypothalamo-neurohypophysial system which consists of hypothalamic nuclei, their axonal fibres forming tractus preoptico-hypophyses and the neurohypophysis) works as a morphological as well as a physiological connection between the hypothalamus and the pituitary gland. In fishes, fibres from the neurosecretory hypothalamic nuclei terminate in the neurohypophysis, which remains inter digitized with the adenohypophysis and provides a very close association between the neurosecretory fibres and pars intermedia of the pituitary gland forming a neuro-intermediate lobe. Hypothalamo-Neurosecretory complex of Xenentodon cancila consists of Nucleus Pre-opticus (NPO), Nucleus Lateralis Tuberis (NLT) and their axonal tracts. NPO is a paired structure situated on either side of the third ventricle anterodorsal to the optic chiasma. NPO is divisible into a dorsal Pars Magnocellularis (PMC) consisting of large neurosecretory cells and Pars Parvocellularis (PPC) formed of smaller neurons. Neurons of PMC and PPC contribute beaded axons to form neurohypophysial tract. Herring bodies are seen in the anterior as well as posterior neurohypophysis.

Immunocytochemical localization, HPLC characterization, and seasonal dynamics of vasotocin in the brain, blood plasma and gonads of the catfish Heteropneustes fossilis

Immunocytochemical distribution and dynamics of vasotocin (VT) were studied in the air-breathing catfish Heteropneustes fossilis in relation to the reproductive cycle. Vasotocin was localized in the brain and ovary by streptavidin–biotin immunocytochemistry. The immunoreactivity was found throughout the hypothalamo–hypophysial neurosecretory system consisting of the magnocellular and parvocellular neurons of the nucleus preopticus, neurosecretory axonal tract and neurohypophysis (NH). The VT neurons showed seasonal changes; they were numerically less in resting phase but increased during the recrudescent phase. The neurons were hypertrophied and degranulated in pre-spawning phase and heavily degranulated and vacuolated in spawning phase. In the NH, the density of VT fibers increased up to the pre-spawning phase and decreased thereafter. In the ovary, VT immunoreactivity was noticed in the follicular layer and varied with the growth of the follicles. Vasotocin was characterized and quantified by a high performance liquid chromatography with UV detection method in the brain, plasma and ovary. Brain and plasma VT concentrations were also assayed with an EIA method, which was more sensitive than the HPLC method with values about 2-fold higher. Vasotocin levels showed significant seasonal and sexual differences with higher concentrations in females in the recrudescent (preparative, pre-spawning and spawning) phase. Brain VT recorded the highest concentration in the preparative phase (both sexes) while plasma (both sexes) and ovarian VT in the spawning phase. The ovarian concentration of VT was 15- and 25-fold higher in the pre-spawning and spawning phases (when expressed per mg protein), respectively, than plasma but lower than brain levels. In testis, VT concentration was relatively low and apparently did not show any significant seasonal variation. The seasonal activity patterns and gonadal distribution of VT indicate a reproductive function of the peptide.

Blockade of Excitability of Hippocampal Neurons after Coagulation of the Dorsal Amygdalofugal Pathway

In chronic experiments on rabbits, we demonstrated that electrolytic destruction of the stria terminalis results in the intense depression of the integral electrical activity of the hippocampus. Characteristics of the responses induced by electrical and chemostimulation of the hippocampus under the above conditions allowed us to conclude that a significant drop in the excitability of hippocampal neurons themselves, but not changes in the structure and intensity of afferent impulsation from the extrahippocampal structures, underlies such a depression. Morphological changes in neurons and satellite glial cells, such as lysis of the Nissl substance, hyperchromatosis, and wrinkling of the cells after destruction of the stria terminalis, were proof of the correctness of our conclusion. It is postulated that one of the main factors underlying the generalized effects observed in our experiments is probably the disturbance of functional characteristics of the hypothalamo-hypophyseal neurosecretory system induced by destruction of the amygdalofugal connections; this disturbance results in significant pathological shifts of metabolism in the hippocampus.

Effects of thymalin and α-tocopherol on morphofunctional state of neuroendocrine system at the early stages of atherogenesis

The effects of thymalin and α-tocopherol on the morphofunctional state of hypothalamohypophyseal neurosecretory system, thyroid gland, and adrenals at the early stages of atherogenesis are described. Correction of pathological changes in the neuroendocrine organs was accompanied by restoration of lipid homeostasis, decrease in intensity of lipid peroxidation, prevention of progressive atherosclerotic alterations in major arteries.

Immunohistochemical demonstration of urotensins I and II in the caudal neurosecretory system of the Japanese charr,Salvelinus leucomaenis, retained in sea water

This paper is concerned with part of the role and function of the caudal neurosecretory system of the charr,Salvelinus leucomaenis, studied by immunohistochemistry. In order to elucidate the different histologic changes, we examined the immunoreactivities of urotenisn I (UI) and urotensin II (UII) in 3 experimental groups: the feral (river) fish, the fresh-water aquarium-, and sea water aquarium-retained fish. Coexistence of UI and UII was demonstrated in most of the smaller and larger neurons distributed in and near the urophyseal system of all 3 groups. However, some of the larger neurons were immunoreactive only to a single hormone, UI or UII. Merely a few neurons indicated no reactivity for either UI or UII. No such clearcut differences were encountered immunohistochemically in the 3 groups. Neuronal and urophysial immuno-reactivity to UI of feral and fresh-water-retained fish was slightly stronger than that of sea water-retained fish. Moreover, in sea water-retained fish, the intensity of immunoreactivity for UI was variable, and the number of neurons positive for UII only was somewhat larger than that in feral and fresh-water-retained fish. A series of UII-positive cerebrospinal fluid (CSF)-contacting neurons were seen in the ependymal and subependymal layers ventral to the central canal of the spinal cord in every group. These CSF-contacting neurons might constitute another neurosecretory system aside from the ordinary caudal neurosecretory system equipped with urophysis. In contrast to the hypothalamohypophysial neurosecretory system, the caudal neurosecretory system did not show any significant changes among the 3 groups. This suggests that urotensins I and II have no essential role in osmoregulation of the charr.

A Light microscopic HRP study of limbic projections to the vasopressin-containing nuclear groups of the hypothalamus

The anterograde HRP technique has been used to define the efferent projections from the lateral septum, amygdala and ventral subiculum to the anterior hypothalamus (AH) with particular attention to the paraventricular nucleus (PVN). Each limbic region was found to project to the PVN in a perinuclear fashion leaving the nucleus itself virtually devoid of HRP-labeled terminals. This projection pattern was also characteristic of the limbic innervation of the supraoptic (SON) and suprachiasmatic (SCN) nuclei. HRP injections into limbic sites has also enabled the description of both efferent and afferent projections to the remainder of the diencephalon. These results extend the observations made previously on the projections from limbic structures to the diencephalon in the rat, particularly in regard to the distinctive relationship ofefferents to the PVN and SON, the major components of the hypothalamo-hypophyseal neurosecretory system. At the light microscopic level it cannot be stated with certainty whether or not such limbic afferents synapse with the dendrites of cells in the PVN, SON or SCN which extend beyond the cellular boundaries of each nucleus.

Effect of butyroxan on ultrastructural changes in the pituitary produced by tetanus toxin

A previous investigation [3] showed that a unique response of the hypothalamo-hypophyseal neurosecretory system (HHNS) arises to injection of tetanus toxin (TT). During the first 5 h the output of neurosecretion was greatly activated and increased, and after 3 days the accumulation of neurosecretory material was associated with degenerative changes in the pituicytes and structural changes in the endothelium.

Influence of damage of hypothalamo-hypophysial neurosecretory system and adrenalectomy on the blood-brain barrier alteration during intracranial hypertension.

Short-term intermittent cerebral compression following the lesion of NSO, NPV or ME alone or with adrenalectomy, caused disturbances in cerebrovascular system. It was characterized by congestion of blood vessels or vasoparalysis with the damage of BBB. These symptoms were much more pronounced in animals in which ME lesion was combined with adrenalectomy. It seems that the decreased level of vasopressor peptides (VSP, Ox) and catecholamines(A, NA) in the blood could be related to the increased activity of cholinergic system and other substances which are responsible for the dilatation of vessels. It is quite possible that the mutual relation of the above mentioned neuro-humoral factors determine the threshold for cardiovascular and cerebrovascular response to cerebral shock. The breakdown of this threshold could occur at the last stage of intracranial hypertension, being expressed by insufficient control of cardiovascular system with the fall of blood pressure and paralysis of cerebral blood vessels, BBB damage, that eventually might lead to brain death.

Morphological investigation of the hypothalamo-hypophyseal neurosecretory system and thyroid gland during intestinal carcinogenesis

The pathomorphology of the hypothalamo-hypophyseal neurosecretory system and thyroid glands of 150 rats of both sexes was studied during intestinal carcinogenesis induced by 1,2-dimethylhydrazine. The latent period of carcinogenesis was shown to coincide with inhibition of neurosecretion in the paraventricular and supraoptic nuclei and with atrophic changes in the thyroid gland. With the appearance of tumors in the intestine, hypertrophy of the neurons and their nuclei and a decrease in the content of neurosecretory substance were found, accompanied by a tendency toward normalization of the structure of the thyroid gland. The period of spreading cancer was accompanied by increasing hypertrophy of the neurons and a decrease in the content of neurosecretory substance, as well as by marked atrophic changes in the thyroid gland.

The hypothalamo-hypophysial system in the ground squirrel, Citellus erythrogenys Brandt. II. Seasonal changes in the classical neurosecretory system of a hibernator.

Monthly observations of the "Gomori-positive" hypothalamo-hypophysial neurosecretory system (HHNS) of the ground squirrel, Citellus erythrogenys Brandt, were carried out light microscopically using several quantitative methods. From the beginning of hibernation, formation of neurosecretory material (NSM) in the neurosecretory cells (NSC) progressively decreases and release of neurohormones from the HHNS is almost fully inhibited. A maximal accumulation of NSM in the perikarya of the NSC and in the posterior pituitary (PP) is found in December. By this time the volume of the cell nuclei and nucleoli is at a minimum. Signs of activation of the HHNS appear and become more conspicuous as the time of arousal from torpor approaches. The amount of NSM in the NSC and the PP decreases simultaneously with the increase in volume of the NSC. Hyperemia and activation of glial elements is visible throughout the HHNS. The morphological signs of activation reach their peak in March. After reproduction is completed (April to beginning of May), the NSC and the PP are almost devoid of NSM. Beginning with June and during the summer and autumn months a progressive accumulation of NSM in the NSC and the PP parallels gradual diminution in the volume of the NSC structures and the glial cells. Mechanisms and effector pathways by which the HHNS influences seasonal adaptation of the organism and reproduction are discussed.

Correction of T-immunodeficiency in mice by bone marrow transplantation from hydrocortisone-treated donors

Ultrastructural studies (electron microscopy) of the caudal part of the hypothalamo-hypophysial neurosecretory system were conducted in rats during experimental tetanus. Its activation was found to occur as soon as the initial period after the injection of the toxin, this being apparently connected with the administration of the heterogenous protein, because inactivated toxin proved to induce the same effect. Changes in the vascular permeability, lipid metabolism and the blood coagulation system were also observed.

Action of diethixime, a new cholinesterase reactivator, on the central nervous system

Methods of quantitative cytochemical analysis were applied to the study of the reaction of the hypothalamohypophysial neurosecretory system (HHNS) to single and course administrations of lithium chloride (in doses of 200 mg/kg). Reaction of the HHNS proved to depend directly on the amount of lithium administered and was characteriaed by the activation of the synthesis and elemination of the neurosecretion with a single administration on the preparation, or depression of the hormonopoiesis in the hypothalamus and exhaustion of the neurosecretion stores in the neurohypophysis in its course application. During the restoration (7 to 30 days after stopping the drug administration) the state of the HHNS gradually approached the initial level. The authors came to the conclusion that the changes in the central mechanisms of the neuro-endocrine regulation at the hypothalamic level caused by lithium were significant in the pathogenesis of the side-action of its salts

Immunocytochemical demonstration of separate vasotocinergic and mesotocinergic neurons in the amphibian hypothalamic magnocellular neurosecretory system.

Using the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the light microscopic level, it was demonstrated that, in the amphibian magnocellular hypothalamo-hypophysial neurosecretory system, vasotocin and mesotocin are synthesized in separate neurons. A tendency to preferential location of the two kinds of neuronal perikarya is described. The neurosecretory perikarya are the origin of separate vasotocinergic and mesotocinergic axons. In the neural lobe, the pattern of distribution of the two types of axons is different. The coarse ventricular "dendrites" of both kinds of neurons are hormone-containing processes. Staining with anti-bovine neurophysin I serum suggested that the vasotocinergic and the mesotocinergic neurons synthesize different neurophysins.

State of the hypothalamo-hypophyseal neurosecretory system of rabbits after anaphylactic shock

With the aid of morphometric and histochemical methods a study was made of the hypothalamo-hypophyseal neurosecretory system of rabbits in anaphylactic shock. The following occurred in rabbits which survived the shock: an enlargement of the perikarions and reduction in the size of the nuclei and nucleoli of the neurosecretory cells; the content of the neurosecretory substance was increased in the whole neurosecretory system. In rabbits which perished from shock the nuclei and the nucleoli of the neurosecretory cells diminished to a lesser extent, perikarion measurements remained unchanged and the content of the neurosecretory substance in the posterior lobe of the hypophysis fell. Thus, in the animals which survived the shock the processes of synthesis of the neurohormones by the neurosecretory cells were sharply activated, but the secretion of the neurohormones from the posterior lobe of the hypophysis was inhibited; in animals which perished from shock the activation of the hormone formation in the neurosecretory cells was less pronounced, but the processes of the secretion of the neurohormones from the posterior lobe were apparently intensified.