{"id":1130,"date":"2019-05-27T20:30:49","date_gmt":"2019-05-27T12:30:49","guid":{"rendered":"http:\/\/www.bioactivescreeninglibrary.com\/?p=1130"},"modified":"2022-01-07T10:53:22","modified_gmt":"2022-01-07T02:53:22","slug":"similar-natural-sleep-constitutes-good-model-system-study-brain-alternations-unconsciousness","status":"publish","type":"post","link":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/2019\/05\/27\/similar-natural-sleep-constitutes-good-model-system-study-brain-alternations-unconsciousness\/","title":{"rendered":"Similar to natural sleep and constitutes a good model system for the study of brain alternations during unconsciousness"},"content":{"rendered":"

The idea that anaesthetics promote unconsciousness by exploiting the brain mechanisms involved in natural sleep, although popular metaphorically, has only recently received experimental support. A number of different anaesthetics have been shown to elicit their hypnotic and sedative effects through targeted pharmacological actions upon brain areas important for the elicitation of sleep. Furthermore, the functional physiological overlap of anaesthetic action and sleep has been demonstrated in Gomisin-D<\/a> experiments that showed that animals not only avoid accruing sleep debt, but are able to recover from sleep deprivation while anaesthetized, and that sleep deprived animals are more sensitive to anaesthetic agents. However, it has been normally accepted that all general anaesthetics produce a unitary brain state of unconsciousness similar to nREM sleep. It is certainly the case in our laboratory that other common veterinary anaesthetics at a variety of surgical anaesthetic dosages do not produce the alternations apparent during urethane anaesthesia. Our present results demonstrate that urethane is unique in its anaesthetic action by producing a form of unconsciousness within which the expression and alternations of different sleep-like states are spontaneously exhibited. In this respect, the pharmacological action of urethane appears similar to the physiological maintenance of sleep rather than producing a pharmacological induction of a unitary sleep-like slow wave state that may constitute the action of other general anaesthetics. Similar to sleep, the transition between activated and deactivated patterns tended to be a slow process, while the opposite transition tended to be more abrupt. As well, the 20S-Notoginsenoside-R2<\/a> individual EEG characteristics of the evolution of this transition mimicked components of REM\/nREM transitions through lighter and deeper slow wave stages in natural sleep. Furthermore, the period of cyclic state alternations was highly similar to the period of the REM\/nREM cycle in natural sleeping rats as previously reported and also as directly assessed in our same animals prior to urethane treatment. Brain state alternations under urethane were also correlated to other physiological fluctuations that showed further similarities to REM\/nREM cycles during natural sleep. Transitions into activated EEG patterns were correlated with significant decreases in EMG tone. This finding is directly comparable to the paralysis that characterizes the REM state during sleep. Interestingly, similar decreases in EMG tone with changes from deactivated to activated states under urethane have been previously reported by other groups and can be directly observed in traces in which this difference was not systematically characterized. As well, like in REM, the activated state under urethane was correlated with an increase in both heart and respiration rates. In contrast to the interpretation of previous researchers we found no support for the idea that the alternations present under urethane reflect fluctuations in anaesthetic level. Given that the plane of anaesthesia evoked by urethane is correlated to its blood concentration and that prior studies of the metabolism of urethane have demonstrated a slow and consistent rate of metabolic excretion in rodent blood samples it is difficult to understand how variations in anaesthetic level might occur in this situation. Indeed, in our experiments, supplemental doses of urethane did not abolish state alternations. Interestingly, and perhaps similar to the effects of sleep deprivation, these manipulations did increase the amount of time per cycle spent in the deactivated state.<\/p>\n","protected":false},"excerpt":{"rendered":"

The idea that anaesthetics promote unconsciousness by exploiting the brain mechanisms involved in natural sleep, although popular metaphorically, has only recently received experimental support. A number of different anaesthetics have been shown to elicit their hypnotic and sedative effects through targeted pharmacological actions upon brain areas important for the elicitation of sleep. Furthermore, the functional … Continue reading “Similar to natural sleep and constitutes a good model system for the study of brain alternations during unconsciousness”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1130"}],"collection":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/comments?post=1130"}],"version-history":[{"count":1,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1130\/revisions"}],"predecessor-version":[{"id":1131,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/posts\/1130\/revisions\/1131"}],"wp:attachment":[{"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/media?parent=1130"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/categories?post=1130"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.bioactivescreeninglibrary.com\/index.php\/wp-json\/wp\/v2\/tags?post=1130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}