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Effects of experimental suppression of active (REM) sleep during early development upon adult brain and behavior in
Insights
Disrupting active sleep (AS) in early life rat development caused lasting brain and behavioral issues, including abnormal ambulation and reduced sexual responses. These findings highlight AS
Area of Science:
- Neuroscience
- Developmental Biology
- Behavioral Science
Background:
- Active sleep (AS) is hypothesized to be crucial for central nervous system development.
- Early life development is sensitive to environmental and pharmacological influences.
Purpose of the Study:
- To investigate the impact of active sleep deprivation on neurodevelopment in rat pups.
- To assess long-term behavioral, morphological, and biochemical consequences of disrupted AS.
Main Methods:
- Three methods were used to reduce AS in Wistar rat pups: clomipramine injection, clonidine administration, and instrumental deprivation.
- Behavioral tests (open-field, sexual response, passive avoidance, dark preference) were conducted in adulthood.
- Brain regions (cerebral cortex, medulla oblongata) were analyzed for weight, DNA, and protein content.
Main Results:
- AS deprivation led to increased adult ambulation and deficient masculine sexual behavior.
- Clomipramine and clonidine treatments resulted in reduced cerebral cortex and medulla oblongata weights, with proportional decreases in DNA and protein.
- Abnormal myoclonic jerks during AS were observed in treated rats.
Conclusions:
- Interference with active sleep during early development causes persistent neurobehavioral and neuroanatomical abnormalities.
- Monoaminergic systems targeted by clomipramine and clonidine are critical for normal AS-related development.
- These findings underscore the importance of undisturbed active sleep for healthy brain maturation.
Abstract:
In order to test the hypothesis that active sleep (AS) is important for the normal development of the central nervous system, 3 different deprivation methods were applied to male Wistar rat pups during the first month of life. Daily injection of clomipramine from 8 to 21 days of age reduced the high level of AS to less than the adult value throughout most of the experimental period. Administration of clonidine from 8 to 21 days of life induced an almost total suppression of AS. Instrumental deprivation, using the 'pendulum' method, led to a significant (but less severe) AS reduction during 2-4 weeks of postnatal age. Open-field behavior testing in adulthood revealed a higher than normal level of ambulation in all 3 experimental groups. Masculine sexual responses were deficient, due to a low level of both mounts and ejaculations, in both clomipramine- and clonidine-treated animals. Neither passive avoidance learning nor dark preference tests revealed any differences between the experimental and control rats. Sleep observations showed that there was an abnormally high incidence of large myoclonic jerks during AS in both clomipramine- and clonidine-treated rats. Subsequent measurement of regional brain weights showed a significant reduction in the cerebral cortex and medulla oblongata, as compared with the respective control groups, in both the clomipramine- and the clonidine-treated rats. In addition, DNA and protein determination in the affected brain areas showed a proportional reduction in the cortex and in the medulla. These results demonstrate that interference with normal functioning either of AS per se or of specific monoaminergic transmitter systems during early development can produce long-lasting behavioral as well as brain morphological and biochemical abnormalities in later life.