Vol 55, No 6 (2019)
- Year: 2019
- Articles: 12
- URL: https://journals.rcsi.science/0022-0930/issue/view/9712
Reviews
Current Views on Schwann Cells: Development, Plasticity, Functions
Abstract
The review addresses current concepts on the origin and functions of Schwann cells (SCs) as well as phenotypic characterization of their precursors at different ontogenetic stages. The necessity of versatile fundamental exploring SCs is dictated by searching for novel ways to stimulate the recovery of peripheral nerve fibers, including cell and gene therapy. Being a major structural component of the nerve, SCs have a decisive influence on degenerative and reparative processes therein. Particularly accentuated is the lack of knowledge of the molecular mechanisms that regulate SCs differentiation at different ontogenetic stages and their plasticity in the pathology of nerve conduction.
Comparative and Ontogenic Biochemistry
Fatty Acid Composition of Gonads and Gametes in the Black Sea Bivalve Mollusk Mytilus galloprovincialis Lam. at Different Stages of Sexual Maturation
Abstract
The fatty acid (FA) composition of eggs and sperm, as well as the gonadal FA dynamics, were studied for the first time in the mussel Mytilus galloprovincialis Lam. (1819) at different stages of its sexual maturation. Currently, this species is being successfully cultivated in the Black Sea. As exemplified by 22 extracted and identified FAs having a chain length of 14–22 carbon atoms, the gonadal FA composition was shown to depend on the mollusk’s sexual maturation stage. An analysis of FA proportions demonstrated that saturated fatty acids (SFAs) account for 100% of the total FA content in female gonads at stages 1 to 3 and in male gonads at stages 1 and 5. The relative SFA content in eggs exceeds that in sperm. Mono- and polyunsaturated FAs (MUFA and PUFA) are characteristic both of male gonads and sperm in which their total content is higher than in female gonads and eggs. The FA content of the gonads and gametes in M. galloprovincialis follows the natural seasonal reproductive cycle of these bivalve mollusks.
Comparative and Ontogenic Physiology
The Dynamics of Gas Analysis Parameters in Young Males of the Magadan Region from Different Generations of Europeoid Migrants and Adaptants
Abstract
Using indirect calorimetry, we examined 1632 young males aged 17 to 21 years, belonging to the Europeoid (Caucasian) race and residing permanently in the city of Magadan. Depending on the duration of adaptation to the conditions of the Northeast of Russia, all male subjects were divided into 3 groups of generation 1, 2 and 3 descendants and a group of newcomers (migrants or adaptants) residing in the Magadan Region for a short period of time (generation 0). It was established that in the lineage from generations 0 to 3 there occurred an optimization of the ventilatory characteristics of the external respiration apparatus aimed at cutting respiratory heat losses during adaptation to extreme conditions of the Northeast, i.e. a decrease in the tidal volume, tidal minute volume, and respiratory rate. Relevant rearrangements of the ventilatory pattern in subjects with a longer duration of residence under the same extreme conditions are paralleled by an improvement of oxygen transport and more efficient use of each respiratory cycle.
The Minimum Audible Movement Distance for Localization of Approaching and Receding Broadband Noise with a Reduced Fraction of High-Frequency Spectral Components Typical of Prebyscusis
Abstract
The minimum audible movement distance was estimated for approaching and receding sound images with a reduced fraction of high-frequency spectral components which reflects an age-related deterioration of auditory perception (presbycusis). Such a reduction can lead to a partial shutdown of the high-frequency binaural auditory mechanism and changes in distance estimation for sound sources positioned at egocentric distances up to 5 m, i.e. in case of making a contact (collision) decision. This study was carried out in free-field conditions using a sound source movement model. The movement was modelled by noise bursts with linearly changing amplitudes, which were emitted by two loudspeakers spaced 3 m apart. The minimum audible movement distance in estimating moving sound images with a reduced fraction of high-frequency signal components was found to be twice as low as for sound images without such a reduction. The data obtained indicate that, provided that the suprathreshold signal encoding mechanisms remain intact, high-frequency level lowering does not increase the minimum audible movement distance.
Feeding Behavior in Fish: Inluence of Long-Term Light Deprivation on Serotonin Effects in the Carp Cyprinus carpio L.
Abstract
The influence of long-term light deprivation (1 and 4 months) on the latency of leaving a start chamber (t1), feeding latency (t2), and food intake (or ration, R) was studied in carp Cyprinus carpio juveniles injected with serotonin (5-HT), as observed during 96 h post injection. It was found that 5-HT has no significant effect on t1 regardless of the illuminance regime (constant dark in experiment vs. alternating light/dark in control) while exerting a maximum effect on t2. One hour after 5-HT injection, t2 increases 5 times in fish deprived of light for 1 month and 11.6 times in those deprived of light for 4 months as compared to the control group. A significant 5-HT-induced decrease in R was observed after 1 month both in experimental and control groups and after 4 months in the experimental (light-deprived) group only. Possible mechanisms underlying the effect of 5-HT on the above parameters of fish feeding behavior under conditions of long-term light deprivation are discussed.
Peculiarities of Cardiohemodynamics and its Autonomic Regulation in Elderly People
Abstract
The study was aimed to the experimental verification of the authors’ hypothesis that in elderly people an endogenous functional mechanism develops during late ontogeny to protect muscle effectors of the cardiovascular system (CVS) against negative effects of excessive activity of the sympathetic nervous system by partial replacement of its neurotransmitter norepinephrine with humoral catecholamines. Experiments were carried out using our original method of arterial piezopulsometry which allows evaluation of cardiohemodynamic parameters, as well as the spectral power of oscillations of VmaxPP and TNN parameters of arterial blood pressure pulse waves caused by regulatory effects of the autonomic nervous and endocrine systems. Such a replacement is assumed to be crucial for raising the metabolic tolerance of the CVS in elderly people to an age-related increase in oxygen deficiency, as well as for reducing the incidence of tachyarrhythmia, stenocardia and other cardiac pathological conditions under the influence of psychoemotional and physical stressors.
Short Communications
Regulatory Effects of Intranasal C-peptide and Insulin on Thyroid and Androgenic Status of Male Rats with Moderate Type 1 Diabetes Mellitus
The Timescale of Adaptation in Tonal Sequence Processing by Mouse Primary Auditory Cortical Neurons
Anticipatory Postural Adjustments for Auditory Motion Information
Reasons for the Increasing Number of Males of the Mussel Mytilus galloprovincialis Lam. Cultivated at the Black Sea Coast (Crimea, Sevastopol)
Pretreatment of Rats with an Allosteric Luteinizing Hormone Receptor Agonist Enhances Chorionic Gonadotropin-Induced Stimulation of Testosterone Production
Abstract
In clinical practice, luteinizing hormone (LH) and chorionic gonadotropin (CG) are used as activators of the LH receptor, leading to the stimulation of gonadal steroidogenesis. However, high doses of gonadotropin preparations cause a number of side effects. Here we demonstrate that the pretreatment of male rats with TP03, an allosteric agonist of the LH receptor, at doses of 7.5–25 mg/kg significantly increases the testosterone production-stimulating effect of CG administered at a dose of 50 IU/rat, which is twice as low as that inducing a maximum steroidogenic effect. We assume that this is due to additivity of the CG and TP03 effects, as well as the potentiating effect of TP03 on CG signaling pathways. Three hours after CG administration to TP03-pretreated rats, the activation pattern of the genes of steroidogenic enzymes and LH receptor exhibits specific changes which mainly concern 3p-dehydrogenase gene expression. The obtained data indicate a prospectivity of TP03 and CG co-application allowing the effective dose of gonadotropin preparations to be reduced.