[Thyroliberin: new physiological effects and prospects of clinical use]. / Tiroliberin, novye fiziologicheskie éffekty i perspektivy klinicheskogo primeneniia.

In addition to the well-known activities of TRH (stimulation of respiration, antidepressant action, increase of motility, antishock action, therapeutic effects against ataxia, and so forth), some new properties were established. TRH was found (1) to stimulate the contractility of lymph vessels in ultra-low doses and to be useful in the treatment of acute pancreatitis; (2) to normalize cerebral circulation in rats and neonates after asphyxia; (3) to improve the electrophysiological parameters of the retina and pigmented epithelium in rats and man, to exert a long-term positive influence on the health status of patients suffering from senile retinal macular dystrophy; (4) to potentiate the analgesic effect of low doses of morphine in a definite range of doses (analog PR-546). It is of paramount importance that most of the indicated activities of TRH may hold promise for clinical application.

[Protective action of thyroliberin and its synthetic analog (PR-546) in craniocerebral trauma]. / Protektornoe deistvie tiroliberina i ego sinteticheskogo analoga (PR-546) pri cherepno-mozgovoi travme.

The effect of TRH and its synthetic analogue (PR-546) devoid of hormonal activity was studied in acute experiments on rats on the model of neurogenic lung edema caused by skull injury. It was proved that the preliminary (for 30 min before the injury) i/p introduction of TRH (in doses 0.5-1 mg/kg) and PR-546 (in doses 4-8 mg/kg) prevented the development of acute edema and the changes of blood gas compositions as well as disorders in breathing after skull injury. It was assumed that the protective effect of studied peptides is possibly achieved through the intensification of breathing and cardiovascular centers activity.

[Recovery of impaired respiratory activity in cats by thyroliberin analog (PR-546) devoid of hormonal properties]. / Vosstanovlenie narushennoi dykhatel'noi aktivnosti koshek analogom tiroliberina (PR-546), lishennym gormonal'nykh svoistv.

Synthetic analogue thyroliberin (PR-546) devoid of hormonal activity, recovered respiration in conditions of hyperventilation, two-sided vagotomy and hypoxia, caused by the 40-70% bleeding. PR-546 (in doses 100-500 micrograms/kg) intravenously injected was shown to abolish diagram activity decreased effect after hyperventilation. Injection of PR-546 to vagotomized cats in 1.5-2 h, increased breathing rate. The breathing activity resumed after long breaks in respiration as a result of peptide injection. The responses to analogue introductions is similar to the thyroliberin effect.

[Recovery from disorders of respiratory activity in cats using thyroliberin]. / Vosstanovlenie narushennoi dykhatel'noi aktivnosti koshek tiroliberinom.

Controlled lung hyperventilation in cats inhibited the activity of the diaphragm muscle with a subsequent stop of respiration after the end of hyperventilation. Thyroliberin (20-30 mg/kg) intravenously was shown to abolish these effects 15-20 min after application. Preliminary introduction of thyroliberin prevented the changes in the respiration rate and depth caused by vagotomy.

[Mechanoreceptor sensitivity of the frog lung to carbon dioxide]. / O chuvstvitel'nosti mekhanoretseptorov legkikh u liagushki k dvuokisi ugleroda.

To reveal CO2-sensitive receptors in the lungs of frogs, studies have been made of the pattern of afferent impulse activity in the pulmonary branch of the vagal nerve in lung preparations during their extension by gaseous mixtures containing 5-8% of CO2. No specific CO2-sensitive chemoreceptors were found. It was found that pulmonary mechanoreceptors exhibit sensitivity to elevated CO2 concentrations which significantly decrease impulse activity in slowly and rapidly adapting mechanoreceptors. It is concluded that the sensitivity of pulmonary mechanoreceptors to CO2 is formed in terrestrial vertebrates at early phylogenetic stages.

[Role of the pulmonary mechanoreceptor apparatus in molding the natural respiration of the frog Rana temporaria]. / Rol' mekhanoretseptornogo apparata legkikh v formirovanii estestvennogo dykhaniia u liagushki Rana temporaria.

In acute experiments on the frog Rana temporaria, studies have been made of the effect of afferent impulsation in pulmonary mechanoreceptors on respiration pattern. Simultaneous recordings were made of total afferent activity in the pulmonary branch of the vagal nerve and of the activity of motor respiratory nerves as an index of respiration pattern. It was shown that to the end of ventilation period, the level of afferentation decreases up to a threshold value which favours the onset of inspiration. Artificial decrease of afferentation level by the increase in CO2 content in the lung or by novocain application to the latter always resulted in extra-inspiration. On vagotomized frogs, it was found that maximum level of afferent influences is necessary for the onset of expiration.

[Stretch receptors of the lungs in the frog Rana temporaria]. / Restseptory rastiazheniia legkikh u liagushki Rana temporaria.

In experiments on isolated lungs, studies have been made on the activity of single afferent fibers during simulated expiration and inspiration. Both slowly adapting and rapidly adapting voluminous stretch receptors were found in the frog lungs. The latter type exhibits the activity also during fast simulated expiration. Using acetylcholine and histamine, it was shown that the level of excitability of the receptors investigated depends on functional condition of the plain muscles in the pulmonary wall.

[Generalization of an instrumental defensive conditioned reflex elaborated to electric stimulation of the hypothalamus in dogs]. / Generalizatsiia instrumental'nogo oboronitel'nogo uslovnogo reflkesa, vyrabatyvaemogo na élektrostimuliatsiiu gipotalamusa sobak.

Generalization of defensive conditioned reflexes elaborated to electrical stimulation of the lateral hypothalamus (LH) was studied in four dogs with electrodes implanted in various structures of the limbic system. Electrocutaneous stimulation was switched off when the dog lifted the foreleg to a definite level. Generalization of the conditioned reflex was manifested in different degrees when testing different formations of the limbic system, or testing one and the same structure, but at different stages of conditioning. Two types of generalization were found: the first one--a well pronounced motor reaction, by its latency, level and duration of lifting the foreleg similar to movements appearing in response to the conditioned stimulus; and the second one--low amplitude or short-term movements differing from conditioned ones. The first type of generalization was observed in response to stimulation of LH, contralateral to the point of signal stimulation, of the ventromedial hypothalamic nucleus, the mammillary bodies and the basal, lateral and to a lesser degree, the central nucleus of the amygdaloid complex; the second type--in response to stimulation of the ventral hippocampus, the medial and lateral septum nuclei.

[Instrumental defensive conditioned reflexes to electric stimulation of the hypothalamus in dogs]. / Istrumental'nyi oboronitel'nyi uslovnyi refleks na élektrostimuliatsiiu gipotalamusa sobak.

An instrumental defensive conditioned reflex to electrical stimulation of the lateral hypothalamus (LHS) was elaborated in seven dogs with electrodes implanted in different structures of the limbic system. Electrocutaneous stimulation was disrupted by a lift of the foreleg to a certain level. The conditioned reflex developed slowly: it appeared at the 15th to 35 th pairing, became stable by the 120--150th pairing of stimuli and reached a 60--90% level. Extinction of the conditioned reflex took 70--80 presentations of the conditioned stimulus without reinforcement. As LHS turned into a signal of electrocutaneous stimulation, the typical reactions to it weakened; in particular, searching movements and sniffing virtually disappeared, while licking movements appeared much more seldom both during the action of the conditioned stimulus and in the intervals between stimuli pairings.