Hormonal and Behavioural Responses of Paradoxical Sleep‐Deprived Rats to the Elevated Plus Maze

Abstract

Activation of the hypothalamic-pituitary-adrenal (HPA) axis is observed immediately after 96 h of paradoxical sleep (PS) deprivation. However, when individually or group PS-deprived rats are challenged with a mild stressor, they exhibit a facilitation of the corticosterone response, and a faster return to basal levels than control rats. Because the housing condition influences coping behaviour, we tested whether the type of PS deprivation (individually or in group) influenced anxiety-like behaviour in the elevated plus-maze and the accompanying adrenocorticotropin (ACTH) and corticosterone responses. Individually (I-DEP) or group deprived (G-DEP) rats and their appropriate control groups were either killed immediately after 96 h of sleep deprivation (time-point 0 or 'basal') or exposed to a 5-min test on the elevated plus maze and sampled 5, 20 or 60 min after test onset. Control of I-DEP rats showed reduced locomotor activity and augmented anxiety-like behaviour, replicating the effects of social isolation. Although I-DEP rats exhibited higher motor activity than cage control rats, these groups did not differ in regard to the percentage of entry and time spent in the open arms. G-DEP rats, in turn, ambulated more, entered and remained longer in the open arms, exhibiting less anxiety-like behaviour. PS-deprived rats exhibited higher ACTH and corticosterone 'basal' secretion than control rats. For all groups, peak ACTH secretion was reached at the 5-min time-point, returning to unstressed basal levels 60 min after the test, except for G-DEP rats, which showed a return at 20 min. Peak levels of corticosterone occurred at 5 min for PS-deprived groups and at 20 min for control groups. G-DEP rats showed a return to 'basal' unstressed levels at 20 min, whereas the I-DEP and control groups did so at 60 min. A negative correlation between exploration in the open arms and hormone concentrations was observed. These data indicate that housing condition influences the subsequent behaviour of PS-deprived rats in the EPM which, in turn, seems to determine the secretion profile of ACTH and corticosterone in response to the test.

Dim light at night interacts with intermittent hypoxia to alter cognitive and affective responses

“…However, it is possible that the HPA axis was still altered by changes in corticosterone earlier during treatment, as reported previously, leading to prolonged changes in adrenal gland masses (47). Increased adrenal masses have been reported in studies of paradoxical sleep deprivation (6,42). IH, in a preconditioning context, has previously been reported to prevent the development of the poststress depression in rats by preventing the disturbance of the HPA axis (35), suggesting an ability of IH treatment to alter HPA axis functioning.…”

The relationship between anxiety and sleep–wake behavior after stressor exposure in the rat

“…Indeed, in clinical studies, sleep deprivation has been an effective form of treatment for major depressive disorders in humans Giedke et al, 2003;Gillin et al, 2001); but deprivation has shown little or negative results in patients diagnosed with anxiety disorders (Dinges et al, 1997;Labbate et al, 1998). Results from recent REM and total sleep deprivation studies in rodents demonstrate the anxiogenic effect of disrupted sleep (Silva et al, 2004;Suchecki et al, 2002a;Suchecki et al, 2002b). The deprivation techniques used, however, also have been shown to induce a considerable amount of stress (Suchecki et al, 1998).…”

Paradoxical sleep deprivation: neurochemical, hormonal and behavioral alterations. Evidence from 30 years of research

“…Importantly, it significantly decreased rearing behavior, which is associated with potentiation of stereotypy and exploratory activity (Andersen et al 2005b). In addition, another study showed that single platform PSD rats had reduced locomotor activity and augmented anxiety-like behavior (Suchecki et al 2002). Recently, Martins and colleagues (2008) pointed out that PSD increased gnawing behavior undirected to feeding, supporting the view that spontaneous oral stereotypy, rather than hunger, is the major cause of increases in food removed from feeders in rats deprived of sleep for up to 96 hours.…”