Effects of desipramine and total sleep deprivation on hormonal levels of healthy subjects

Sleep deprivation decreases binding of [11C]raclopride to dopamine D2/D3 receptors in the human brain

Sleep deprivation did not affect dopamine transporters (target for most wake-promoting medications) and thus dopamine increases are likely to reflect increases in dopamine cell firing and/or release rather than decreases in dopamine reuptake. Because dopamine-enhancing drugs increase wakefulness, we postulate that dopamine increases after sleep deprivation is a mechanism by which the brain maintains arousal as the drive to sleep increases but one that is insufficient to counteract behavioral and cognitive impairment. Sleep deprivation can markedly impair human performance contributing to accidents and poor productivity. The mechanisms underlying this impairment are not well understood, but brain dopamine systems have been implicated. Here, we test whether one night of sleep deprivation changes dopamine brain activity. We studied 15 healthy subjects using positron emission tomography and [11C]raclopride (dopamine D2/D3 receptor radioligand) and [11C]cocaine (dopamine transporter radioligand). Subjects were tested twice: after one night of rested sleep and after one night of sleep deprivation. The specific binding of [11C]raclopride in the striatum and thalamus were significantly reduced after sleep deprivation and the magnitude of this reduction correlated with increases in fatigue (tiredness and sleepiness) and with deterioration in cognitive performance (visual attention and working memory). In contrast, sleep deprivation did not affect the specific binding of [11C]cocaine in the striatum. Because [11C]raclopride competes with endogenous dopamine for binding to D2/D3 receptors, we interpret the decreases in binding to reflect dopamine increases with sleep deprivation. However, we cannot rule out the possibility that decreased [11C]raclopride binding reflects decreases in receptor levels or affinity. Sleep deprivation did not affect dopamine transporters (target for most wake-promoting medications) and thus dopamine increases are likely to reflect increases in dopamine cell firing and/or release rather than decreases in dopamine reuptake. Because dopamine-enhancing drugs increase wakefulness, we postulate that dopamine increases after sleep deprivation is a mechanism by which the brain maintains arousal as the drive to sleep increases but one that is insufficient to counteract behavioral and cognitive impairment.

Effect of sleep deprivation on the growth hormone response to the alpha-3 adrenergic receptor agonist, clonidine, in normal subjects

One night's sleep deprivation (SD) increased the growth hormone (GH) response to clonidine (20 ug/kg i.v.) in 11 normal men ( p < 0.005). This finding may indicate that SD enhances alpha-2 adrenergic receptor function or that the GH response to GH releasing factor in increased by SD.

Influence of partial sleep deprivation on the secretion of thyrotropin, thyroid hormones, growth hormone, prolactin, luteinizing hormone, follicle stimulating hormone, and estradiol in healthy young women

The influence of partial sleep deprivation during the second half of the night on the secretion of thyroid stimulating hormone (TSH), thyroxin (T4), free T4 (fT4), triiodothyronine (T3), prolactin (PRL), growth hormone (GH), luteinizing hormone (LH), follicle stimulating hormone (FSH), and estradiol (E2) was investigated in 10 healthy young women. Blood samples were drawn at hourly intervals over a 64-hour period (i.e., 3 consecutive days and nights). During night 2, all subjects were awakened at 1:30 a.m. During partial sleep deprivation, TSH concentrations increased significantly and remained elevated throughout the following day. Levels of T4, fT4, and T3 were enhanced during the partial sleep deprivation hours only, and changes in these hormones seemed to be independent of TSH. PRL levels decreased, LH and E2 concentrations increased, and GH and FSH secretion remained unchanged during partial sleep deprivation. This pattern of change of different endocrine axes during partial sleep deprivation resembles those seen after total sleep deprivation, suggesting that similar neurochemical changes are induced by both forms of antidepressant therapy. The late evening GH peak occurred almost exclusively before the onset of sleep. Partial sleep deprivation did not influence the chronobiological profiles of any of the hormones investigated. The chemical changes underlying these alterations are speculated to involve enhancement of central norepinephrine and dopamine activity with a concomitant increase in the activity of the sympathetic nervous system.

Thyrotropin (TSH) and thyroid hormone concentrations during partial sleep deprivation in patients with major depressive disorder

Thyrotropin (TSH), thyroxine (T4), free T4, triiodothyronine (T3), and free T3 (fT3) concentrations were measured in 25 patients with major depressive disorder at 8 a.m. both before and after partial sleep deprivation (PSD) during the second half of the night. Significant increases in TSH and T3 levels and a corresponding trend in fT3 levels were seen. No convincing correlations occurred between changes in the secretion of any of the hormones and the antidepressant effect of PSD. However, this does not rule out the possibility that the two phenomena, which occur in depression at different anatomical levels with presumably different degrees of disturbance in the respective receptor systems, have common underlying neurochemical mechanisms. Comparison of the effect of the PSD on changes in hormone secretion and mood with the corresponding effects in a sample of depressed patients who underwent total sleep deprivation showed no significant differences between the effects of these two forms of sleep deprivation on either variable.

Growth hormone response to desmethylimipramine in depressed and suicidal adolescents

Desipramine 75 mg i.m. was given in the morning to 20 adolescents with major depressive disorder and 23 normal controls. Depressed adolescents secreted significantly less growth hormone (GH) over the next 2 h than did normal adolescents, although a substantial proportion of the differences were accounted for by the depressed adolescents who had a specific suicidal plan or attempt during the episode. Severity of depression or the presence of other depressive symptoms did not predict GH secretion within the depressed group. Age, sex and maturational factors in the control of GH are discussed. It is concluded that these differences in GH secretion probably reflect differences in CNS beta-adrenergic and/or serotonergic function. Suicidality and depression may have different psychobiological correlates in adolescents.