Q27096323
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Rhaponticum carthamoides, maral root, is being used, namely in Orient, for centuries. The focus of interest of medicinal chemists has recently been pointed to its chemical components, namely 20-hydroxyecdysone, a herbal drug with very low toxicity. It is registered in the EU to cure, e.g., Duchenne muscular dystrophy. Moreover, being recognised as an adaptogen, it has been in use to cure prediabetes and can be classified as a natural substance, for which intensive research into cancer and leukaemia treatment is running, in some cases together with bufadienolides. Ecdysteroids also have the ability to affect drug resistance in the treatment of tumours. The paper brings the digest of the most interesting information, mainly from the human health research.
The polyhydroxylated derivatives of 6-keto,7-dehydrocholesterol (ecdysone, ecdysteroids, Ecd) are natural compounds widely distributed in plants. They exhibit strong anabolic, vitamin D-like, pharmacological effects in vertebrate animals and in the human body. In the larval stages of insects, injections of pure Ecd cause serious pathophysiological, "hyperecdysonic" syndromes associated with neuromuscular paralysis, premature cuticular apolysis and complete inhibition of ecdysis. Ecds do not penetrate insect cuticle. For this reason, all previous attempts to induce ecdysone responses by topical applications of Ecd failed. In this work, we tried to induce the topical effects of Ecd by preparation of more lipophilic complexes, with 2 or 4 molecules of 20-hydroxyecdysone (E20) attached to a relatively large nucleus of the porphyrin. The resulting porphyrin-E20 complexes (ecdysogens) have been subjected to standardised assays for ecdysone activity in the ligatured larvae ("dauerlarvae") of the greater waxmoth (Galleria mellonella). Similarly like the free E20 alone, porphyrin-E20 complexes had no effect when applied on the body surface or administered in the larval diet. When injected, however, they exhibited delayed effects, but the adverse ("hyperecdysonic") pathophysiological syndromes were reduced or abolished. It is concluded, therefore, that the replacement of pathophysiological, precocious or "hyperecdysonic" moults by the larval-pupal transformation, was due to successive metabolic liberation of the biologically active, free E20 from the porphyrin-E20 complex. The biological status of Ecd does not agree with their definition as the prothoracic gland (PG) hormone of insects, nor with the assumptions about a growth hormone of plants. A possibility that the most important status of Ecd may depend on the pharmacological properties of a sterolic D6 vitamin has been discussed.
- MeSH
- aplikace lokální MeSH
- aplikace orální MeSH
- biologická proměna účinky léků MeSH
- ekdysteron aplikace a dávkování chemie farmakologie fyziologie MeSH
- kukla účinky léků MeSH
- larva účinky léků MeSH
- Lepidoptera účinky léků fyziologie MeSH
- porfyriny chemie farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
During the late larval period, the salivary glands (SG) of Drosophila show a cascade of cytological changes associated with exocytosis and the expectoration of the proteinaceous glue that is used to affix the pupariating larva to a substrate. After puparium formation (APF), SG undergo extensive cytoplasmic vacuolation due to endocytosis, vacuole consolidation and massive apocrine secretion. Here we investigated possible correlations between cytological changes, the puffing pattern in polytene chromosomes and respiratory metabolism of the SG. The carefully staged SG were explanted into small amounts (1 or 2μl) of tissue culture medium. The respiratory metabolism of single or up to 3 pairs of glands was evaluated by recording the rate of O2 consumption using a scanning microrespirographic technique sensitive to subnanoliter volumes of the respiratory O2 or CO2. The recordings were carried out at times between 8h before pupariation (BPF), until 16h APF, at which point the SG completely disintegrate. At the early wandering larval stage (8h BPF), the glands consume 2nl of O2/gland/min (=2500μl O2/g/h). This relatively high metabolic rate decreases down to 1.2-1.3nl of O2 during the endogenous peak in ecdysteroid concentration that culminates around pupariation. The metabolic decline coincides with the exocytosis of the proteinaceous glue. During and shortly after puparium formation, which is accompanied cytologically by intense vacuolation, O2 consumption in the SG temporarily increases to 1.6nl O2/gland/min. After this time, the metabolic rate of the SG decreases downward steadily until 16h APF, when the glands disintegrate and cease to consume oxygen. The SG we analyzed from Drosophila larvae were composed of 134 intrinsic cells, with the average volume of one lobe being 37nl. Therefore, a single SG cell of the wandering larva (with O2 consumption of 2nl/gland/min), consumes each about 16pl of O2/cell/min. A simultaneous analysis of the rate of protein and RNA synthesis in the SG shows a course similar to that found in respiratory metabolism.
- MeSH
- bazální metabolismus MeSH
- biologická proměna MeSH
- chromozomy hmyzu MeSH
- Drosophila melanogaster růst a vývoj metabolismus MeSH
- exocytóza MeSH
- larva růst a vývoj metabolismus MeSH
- slinné žlázy cytologie růst a vývoj metabolismus MeSH
- spotřeba kyslíku MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The heartbeat of diapausing pupae of the flesh fly Sarcophaga crassipalpis was investigated using electrocardiographic methods including gravimetry, thermography, and optocardiography. During deep diapause, characterized by minimum metabolic activity, the heart exhibited discontinuous bouts of exclusively unidirectional, anterograde pulsations (40-60 contractions/min) that lasted only a few seconds. These bouts of cardiac pulsations were separated by periods of rest lasting 5-30 min. During infradian peaks of metabolic activity (4-day cycles) that occur throughout diapause, periods of rest were shortened and frequency of the anterograde heartbeat increased more than two-fold. Throughout diapause, the heart consistently exhibited a simple, bi-phasic pattern of pulsations generated by bouts of anterograde heartbeats interspersed with periods of cardiac rest. When the fly broke diapause and initiated pharate adult development, a new tri-phasic pattern was observed: the new pattern incorporated heartbeat reversal, as noted by the appearance of retrograde pulsations that directed hemolymph in a posterior direction. These retrograde heartbeats occurred exclusively in the abdominal portion of the dorsal vessel and were not observed in the head or thorax. The transition to pharate adult development was also accompanied by the appearance of extremely strong extracardiac pulsations that served a respiratory function. Although these pulsations made it more challenging to record heartbeat patterns in pharate adults, we observed progressive shortening of the resting periods and a continual increase in the rate of both anterograde and retrograde pulsations, a trend that was further magnified in the adult fly (anterograde contractions up to 300/min and retrograde contractions approximately 125/min). These results imply that the circulatory function of the heart is homeostatically regulated and is responsive to developmental changes and the diverse metabolic rate demands of larvae, diapausing pupae, pharate adults and adult flies.
- MeSH
- cykly aktivity MeSH
- diapauza hmyzu * MeSH
- hemolymfa fyziologie MeSH
- kukla fyziologie MeSH
- Sarcophagidae růst a vývoj MeSH
- srdeční frekvence MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Recent electrocardiographic (ECG) studies of insect hearts revealed the presence of human-like, involuntary and purely myogenic hearts. Certain insects, like a small light-weight species of hoverfly (Episyrphus balteatus), have evolved a very efficient cardiac system comprised of a compact heart ventricle and a narrow tube of aorta, which evolved as an adaptation to sustained hovering flights. Application of thermocardiographic and optocardiographic ECG methods revealed that adult flies of this species use the compact muscular heart chamber (heart ventricle) for intensive pumping of insect "blood" (haemolymph) into the head and thorax which is ringed all over with indirect flight musculature. The recordings of these hearts revealed extremely high, record rates of forward-directed, anterograde heartbeat (up to 10Hz), associated with extremely enhanced synchronic (not peristaltic) propagation of systolic myocardial contractions (32.2mm/s at room temperature). The relatively slow, backward-directed or retrograde cardiac contractions occurred only sporadically in the form of individual or twinned pulses replacing occasionally the resting periods. The compact heart ventricle contained bi-directional lateral apertures, whose opening and closure diverted the intracardiac anterograde "blood" streams between the abdominal haemocoelic cavity and the aortan artery, respectively. The visceral organs of this flying machine (crop, midgut) exhibited myogenic, extracardiac peristaltic pulsations similar to heartbeat, including the periodically reversed forward and backward direction of the peristaltic waves. The tubular crop contracted with a periodicity of 1Hz, both forwards and backwards, with propagation of the peristaltic waves at 4.4mm/s. The air-inflated and blindly ended midgut contracted at 0.2Hz, with a 0.9mm/s propagation of the peristaltic contraction waves. The neurogenic system of extracardiac haemocoelic pulsations, widely engaged in the regulation of circulatory and respiratory functions in other insect species, has been replaced here by a more economic, myogenic pulsation of the visceral organs as a light-weight evolutionary adaptation to prolonged hovering flight. Striking structural, functional and even genetic similarities found between the hearts of Episyrphus, Drosophila and human hearts, have been practically utilised for inexpensive testing of new cardioactive or cardioinhibitory drugs on insect heart.
- MeSH
- Diptera fyziologie MeSH
- elektrokardiografie MeSH
- hemolymfa fyziologie MeSH
- kontrakce myokardu MeSH
- lidé MeSH
- srdce fyziologie MeSH
- srdeční frekvence MeSH
- srovnávací fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Larvae of the greater waxmoth (Galleria mellonella) become paralysed by the venom of the braconid wasp (Habrobracon hebetor) a few minutes after intoxication. The profound neuromuscular paralysis, which may last for several weeks, includes all somatic muscles that are innervated through neuromuscular transmission. The peristaltic contractions of the heart and intestine, which are regulated by the depolarisation potentials of the myocardium or intestinal epithelial muscles, remain unaffected and fully functional. Heartbeat patterns and intestinal pulsations were monitored in the motionless, paralysed larvae by means of advanced electrocardiographic recording methods (contact thermography, pulse-light optocardiography). The records revealed more or less constant cardiac pulsations characterised by 20-25 systolic contractions per minute. The contractions were peristaltically propagated in the forward (anterograde) direction, with a more or less constant speed of 10mm per second (23-25°C). Additional electrocardiographic investigations on larvae immobilised by decapitation revealed the autonomic (brain independent) nature of heartbeat regulation. Sectioning performed in the middle of the heart (4th abdominal segment) seriously impaired the pacemaker rhythmicity and slowed down the rate of heartbeat in the anterior sections. By contrast, the functions of the posterior compartments of the disconnected heart remained unaffected. These results confirmed our previous conclusions about the existence of an autonomic, myogenic, pacemaker nodus in the terminal part of an insect heart. They show an analogy to the similar myogenic, sinoatrial or atrioventricular nodi regulating rhythmicity of the human heart. Peristaltic contractions of the intestine also represent a purely myogenic system, which is fully functional in larvae with complete neuromuscular paralysis. Unlike the constant anterograde direction of the heartbeat, intestinal peristaltic waves periodically reversed anterograde and retrograde directions. A possibility that the functional similarity between insect and human hearts may open new avenues in the field of comparative cardiology has been discussed.
- MeSH
- biologické hodiny účinky léků MeSH
- elektrokardiografie metody MeSH
- kousnutí a bodnutí hmyzem patofyziologie MeSH
- můry účinky léků fyziologie MeSH
- nervový přenos účinky léků MeSH
- peristaltika účinky léků MeSH
- srdeční frekvence MeSH
- sršňovití MeSH
- střeva fyziologie MeSH
- svaly patofyziologie MeSH
- vosí jedy farmakologie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
