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Biomedical subjects

A S Kaplanskiĭ

Publications and source records attributed to A S Kaplanskiĭ.

At least 19 recordsLinked to original sources
PubMed2004

[Morpho-functional endocrine glands changes in male and female rats under deficiency of functional loading].

Histomorphometric and immunocytochemical methods were employed in comparative morphofunctional analysis of the endocrine glands of female and male rats deprived of support loads on the hind limbs by tail suspension. It was shown that pituitary somatotrophs, pancreatic insulocytes and thyroid calcitonin-producing cells in females and males react to deficiency of support loading equally by reducing the functional activity. Blood testosterone decreases in the tail-suspended rats and concurrent hyperplasia of Leydig's cells in testicles are suggestive of an abnormal testosterone synthesis/secretion by these cells in consequence of resticle displacement toward the abdomen. Activation of adenohypophysial gonadotrophs producing the luteinizing hormone that controls the Leydig's cells proliferation appears to be a feedback reaction of gonadotrophs to the low testosterone level in blood.

Animals↗
PubMed2003

[Morphofunctional changes in the endocrine system of male rats during microgravity and suspension].

Morphofunctional changes in somatotrophs and gonadotrophs of the adenohypophysis and Leydig's cells in the testicles were investigated histologically and hystomorphometrically in male rats following microgravity or tail-suspension. Deficient loading of the musculoskeletal system in microgravity was shown to suppress the functional activity of somatotrophs, gonadotrophs and, seemingly, Leydig's cells. As a consequence, blood levels of the growth hormone and testosterone reduced in the space-flown rats. Reduction of the production of the main anabolic hormones is one of the causes for growth inhibition, prevalence of catabolism and consequent muscular atrophy and osteopenia. Simulation of the lack of weight loading inherent to the zero-g environment by suspension also leads to suppression of the somatotrophs activity, whereas the concentration and functional activity of gonadotrophs make a sharp rise. Proliferation of Leydig's cells in the testicles was noted to be very high despite desolation of the seminal canals and disintegration of the testicle epithelium. These findings drive to the conclusion that suspension affects deeply the spermiogenous and androgenous functions of the testicle which is not observed in animals exposed to microgravity. These differences evidence that genesis of the musculoskeletal atrophy in the suspended and space-flown rats was dissimilar.

Animals↗
PubMed2003

[Comparative histomorphometric studies of shin bones of male and female rats following tail suspension].

In a 30-d experiment with tail-suspension of male and female rats histomorphometric studies were performed to compare impacts of deficient weight loading on the tibial spongy tissue. The 30-d suspension was found to slow down the body and adrenal mass gain irrespective of sex; however, this effect was more pronounced in male rats suggesting a greater stress to males as compared to females. Also, suspension caused tibial osteopenia in either of sexes. Decreases in the tibial spongy mass in suspended male and female rats were similar to control. At the same time, inhibition of the longitudinal bone growth attested by diminished height of the cartilaginous growth plate was more noticeable in males as compared with females. We attribute this observation to the reduction in testosterone production and a more violent stress reaction.

Adrenal Glands↗
PubMed2003

[Effects of ibandronate on the osteopenia process in tail-suspended rats].

Histological and histomorphometric effects of ibandronate on the metaphyseal spongiosis in tibia were studied in tail-suspended rats and their controls in a 30-d experiment. Ten- to twenty-day course of ibandronate at a dose of 6 micrograms/kg of the body mass per diem altered the architectonics of metaphyseal spongiosis and increased materially the total spongiosis volume no matter whether those were suspended rats or controls. Spongiosis growth was a result of a sharp deterioration of resorption and spongy bone remodelling due to ibandronate. The substance also exhibited a strong durable action inferring that it might be used for prevention of osteopenia for lack of loading on the musculoskeletal system.

Adrenal Glands↗
PubMed2002

[Healing fibular bone fracture in rats during extended suspension ].

Healing of peroneal bone fracture was studied histologically and histomorphologically in rats exposed to a 30-d tail-suspension. To fracture bones, anesthetized rats were operated on day 15 of suspension. Hind limb deprivation of the support loading for a period of 30 days minimizes healing processes in fractured peroneal bones as was evidenced by undersized callus and lowered strength of bone consolidation. Mass-metric and histomorphometric investigations showed that, as compared with the control, on day 15 of regeneration the callous mass and volume in the suspended rats were by 34% and 35% less, respectively; the newly formed spongy bone, the fibrous-cartilaginous tissue and the cartilage were by 44%, 70% and 86% smaller in size, respectively. Nonetheless, healing dynamics in the suspended rats was not disturbed and the calluses were on the same phase of development as in the control, which is attested by similarity of the histological picture. Based on the comparative retrospective analysis of fracture healing in rats in 15- and 30-d experiments, the extended (30-d) suspension did not further impede the post-traumatic bone regeneration. It is suggested that minimization of bone fracture healing during the 15-d suspension was conditioned not only by inhibition of the growth hormone production but also by an acute stress reaction in the early period of adaptation.

Animals↗
PubMed2001

[Age-related characteristics of osteopenia in rats caused by deficient support loads on hind limbs].

Progress of osteopenia in 40-, 100-, and 220-d old rats who had been suspended by tails to release support loading on their hind limbs for 30 days was compared. Deficient support loading was shown to inhibit the longitudinal growth of tibia and produce osteopenia of the proximal metaphysis spongiosis in all groups of rats. Humerus of the rats whose front limbs were still partially loaded, suffered same changes as tibia though much less pronounced. Inhibition of bone growth in length and osteopenia in bone spongiosis reached maximum dimensions in 220-d old rats as a result of summation of kindred changes due to the load deprivation, and aging. Established was a correlation between suppression of the functional activity of STH-cells in adenohypophysis and progress of bone atrophy during suspension. Functional activity of thyroid calcitonin-producing cells was also reduced with the maximum decline in the 40-d old rats.

Age Factors↗
PubMed2001

[Stimulation of bone fracture healing in rats under the support load deficit].

Experiment with rats the hind limbs of which were deprived of support loads (tail suspension) for two weeks following operational fracture of fibular bones evidenced inhibited callus formation and lowered strength of bone fragments consolidation. Injection of anabolic steroid retabolite to the traumatized animals together with limited support loading was favorable to the bone callus formation and consolidation of fragments. This measure also distinctly increased the functional activity of adenohypophysial somatotrophs (growth hormone producers) and thyroid C-cells (calcitonine producers). The direct dependence of bone fracture healing on the somatotropic function of the adenohypophysis suggests that the favorable effect of retabolite combined with the support loading is at least partly achieved through the somatorophic function of the adenohypophysis.

Animals↗
PubMed2001

[Functioning of endocrine glands controlling calcium turnover in microgravity].

Presented are literary and authors' data on functioning of the endocrine glands involved in the control of calcium turnover in microgravity. On analysis of research findings the conclusion has been made that exposure to microgravity stimulates functional activity of the parathyroid and suppresses thyroid C-cells producing the parathyroid hormone and calcitonin, respectively. Shifts in the calcium-controlling endocrine systems are considered to be adaptive and play an important role in pathogenesis of disorders in calcium turnover in microgravity.

Animals↗
PubMed2000

[Ethics of space life science research with animals].

The authors present a historical sketch on the ethics of use of animals in life sciences experiments. Experiments with animals are necessary to expand knowledge in the field of life sciences including the space ones, and health service. It is emphasized that these experiments must be performed with observance of certain moral rules and utilize minimum animals suffice to obtain statistically significant data. The first draft of SRC-IBMP Guidelines on the use of laboratory animals has been published.

Aerospace Medicine↗
PubMed1999

[Role of growth hormone underproduction and support load deficit in development of muscle atrophy and osteopenia in tail-suspended rats].

In a 20-day experiment with tail-suspended male rats histological and histomorphometric techniques were used to study the effects of growth hormone, thyroxin, and graded support loads on the progress of atrophy in soleus and gastrocnemius m.m., tibial metaphyses spongiosis, and growth of tibiae. Daily injections of growth hormone at a dose of 0.5 mg/kg of the body mass were found to restore the longitudinal growth of tibiae and to suppress osteopenia in the spongiosis of metaphyses; however, they did not have any noteworthy effect on the muscular atrophy in the suspended rats. Support loading of the hind limbs for 2 hours a day in parallel to the treatment with growth hormone and thyroxin (0.02 mg/kg of the body mass per a day) suppressed the atrophy in soleus m. but not in gastrocnemius m. They were not able to oppose to osteoporosis in tibial metaphyses spongiosis; tibial growth was not normalized. Thyroxin did not appear to markedly influence muscle and bone atrophies; moreover, it made hypofunctioning of the thyroid more intense and, when combined with the growth hormone, masked the positive effect of the latter on the rats' bones.

Animals↗
PubMed1999

[The effect of support loads and CNS stimulants on the development of the atrophic process in the muscles of suspended rats].

The histomorphometric method there was used to study effects of ephedrine, strychnine, and support loads on the atrophy of m. soleus and m. gastrocnemius in rats with load-deprived lower extremities (14-day tail-suspension). Deficiency of support loads on the lower extremities led to atrophy of the muscles, especially the slow m. soleus. Injections of ephedrine (0.06 mg/kg), strychnine (0.015 mg/kg) as well as ephedrine and strychnine at one and the same time did not affect the development of atrophy. On the contrary, daily 2-hr support loading of the rear extremities had a favourable effect on the muscle atrophy as it was slowed down. Particularly effective were injections of ephedrine on the background of support loads following which the mass of m. soleus in the suspended rats was close to vivarium control. It is suggested that the preventive effect of ephedrine is associated with stimulating the CNS controllers of the somatotropic function of the pituitary body and eventual enhancement of the somatotropic hormone production.

Animals↗
PubMed1998

[Effect of ephedrine and support loads on development of osteopenia and growth of shin bones in suspended rats].

Effects of graded support loads and stimulators of the central nervous system (ephedrine and strychnine) on growth of bones and the volume of spongy bone tissue in the proximal metaphyses of the shin bones were studied in the 14-day experiment with rats suspended by tail in the orthostatic position. It is indicated that the support loads in combination with ephedrine injection prevent the suspension-induced inhibition of bone growth and development of osteopenia of spongiosa of metaphyses. The preventive effect of support loads and ephedrine relates with their stimulating influence on the functional activity of the STH-cells of adenohypophysis producing the growth hormone.

Animals↗
PubMed1998

[Effects of support++ loads and stimulation of CNS on functional activity of somatotrops and thyreocytes in suspended rats].

In the 14-day experiment with suspended rats there investigated the effect of support loads and stimulated of CNS (ephedrine and strychnine) on functional activity of somatotrops of adenohypophysis and thyrocytes of the thyroid gland. It is shown that the support loads and stimulators of the CNS increase the functional activity of somatotrops and thyreocytes. As this takes place, the loads of support give rise to the elevation of production and secretion of the growth hormone and thyroid hormones whereas ephedrine induces mainly the secretion of growth hormone. It is concluded that the support loads and stimulator of the CNS are able compensate in part a deficit of afferentation developing in the rats during suspension.

Adaptation, Physiological↗
PubMed1998

[Comparative analysis of changes in rats organisms exposed to microgravity and head-down suspension].

Comparative analysis of metabolic and structural shifts in rats following 14 days of microgravity aboard biosatellite Cosmos-2044 and their tail-suspended synchronous controls gave evidence that suspension-induced deprivation of hind limbs of support loading yields inherent to microgravity shifts the endocrine control of energy, plastic, and mineral metabolism. The conclusion has been drawn that tail-suspension can be used as a model of the microgravity effects on the musculoskeletal apparatus and the endocrine systems controlling metabolism in muscles and bones.

Animals↗