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

Abstract

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.

Research Article: Development of the Control System for Artificial Reproduction of Fish Populations Based on a Complex of Neroendocrinological Research and Biotech Innovations

“…Analysis of the results led to the conclusion that the functional role of HHNS in fish reproduction is to initiate the starting energy-consuming processes of migratory and spawning behavior and to complete spawning by suppressing the hyperactivity of the complex of visceral target organs, especially the reproductive system. The latter ensures the transition of the organism from the energetic type of metabolism to energy-saving plastic metabolism (in the form of "metabolic reversion") [2,17]. The final conclusion about the important key role of HHNS in the integration of fish reproduction (according to the principle of self-regulation) allows us to present a constructive working scheme (Fig.…”

“…That is why the degree of plasticity of the HHNS turns out to be sufficient for its participation in the integration of fish reproduction. The idea is expressed that the key links of biological integration systems are organized according to this general structural and functional principle [2,17].…”

“…Under laboratory conditions, experiments were carried out on the roach Rutilus rutilus caspicus (Jakowlew, 1870), the rainbow trout Parasalmo mykiss (= Oncorhynchus mykiss) (Walbaum, 1792) and the African clary catfish Clarias gariepinus (Burchell, 1822), as promising objects for aquaculture. The state of the HHNS was studied histomorphologically, electron microscopically and immunohistochemically on microimage analyzers "Morphoquant", "Videotest" and in electron microscopes JEM-100b and Tesla-500 [2]. Comparative results of production inspections were assessed according to the most important fish-breeding biological, morphometric and morphophysiological indicators.…”

“…For the first time, the participation of HHNS in fish reproduction was established by us due to the use of quantitative morphometric methods for assessing its functional state and comparative analysis of the results of the ecological-histophysiological direction of research [2]. Already a preliminary analysis of the results of the ecological-histophysiological study shows a fundamental similarity in the mechanisms of the participation of HHNS in the implementation of migrations and spawning and suggests that the functional role of HHNS is to initiate and complete reproduction in general.…”

“…This makes it possible to present a simple working scheme for the neuroendocrine integration of fish reproduction according to the principle of self-regulation, which can be constructive enough for the development of new methods of control over reproduction biotechnology. An increase in its efficiency is necessary due to the extremely stressed state of populations of salmonid fish (Atlantic salmon, brown trout, char and Volkhov whitefish) in the Northwest region, the number of which is supported exclusively by hatchery reproduction [2,4]. The decrease in their numbers (before the prohibitions on fishing) occurred due to the cessation of natural spawning and insufficient efficiency of hatchery reproduction, which harvests spawners in spawning grounds (to the detriment of natural spawning) and releases one-year-old juveniles of salmon (weighing up to 26 g) with a survival rate in nature of only 0.4 %, at a rate of 1.9% [2,4].…”