Effects of diazepam and its metabolites on nocturnal melatonin secretion in the rat pineal and Harderian glands. A comparative in vivo and in vitro study

Role of Melatonin in the Management of Substance Addiction: A Systematic Review

Recent evidence links melatonin hormone and its receptor to the etiology and behavioral manifestation of addiction. The role of exogenous melatonin in addiction treatment is still inconsistent and unclear. The present study aimed to review the literature on randomized clinical trials that evaluated the role of melatonin supplementation, compared to placebo, in the treatment of various substance addictions. The literature searches of relevant articles published in the English language in MEDLINE and Google Scholar databases were performed from inception up to May 2021. We included only randomized clinical trials investigating the effect of melatonin treatment, compared to placebo, on substance addiction-related parameters. Non-randomized clinical trials, observation studies, and animal studies were excluded. The risk of bias-2 was used to assess the quality of the studies. Of 537 articles, 12 randomized control trials (RCT) met our inclusion criteria. Studies have been conducted on substances of addiction including benzodiazepine (BZD), alcohol, nicotine, and opioids. Our results indicated that melatonin treatment had mixed results in improving sleep quality and was not found beneficial in BDZ cessation/discontinuation rate among patients with BDZ dependence. Sleep quality and mental health had improved by melatonin supplements in opioid addiction. In nicotine addiction, melatonin treatment showed effectiveness only on mood changes but not in performance tests. In patients with alcohol use disorder (AUD), melatonin treatment did not show any improvement in sleep quality. We found that the use of exogenous melatonin in substance addiction has mixed results which do not provide sufficient evidence, relative to randomized clinical trials, to establish its role.

[Light Therapy for Prevention of Delirium in Critically Ill Patients: What's the Evidence?]

Circadian dysrhythmia affects the majority of ICU patients and has far-reaching effects on organ functioning. At the level of the central nervous system, circadian misalignment facilitates executive cognitive dysfunction and the development of ICU delirium. The pathophysiological mechanisms, especially in the cohort of critically ill patients, appear to be complex, multilayered and far from understood. Results from preliminary research indicate that multidimensional, patient-specific chronotherapeutic concepts developed specifically for the ICU setting may help improve the healing process of patients. Circadian lighting therapy might be a promising intervention in this context.

The Harderian gland: Endocrine function and hormonal control

The Harderian gland (HG) is an exocrine gland located within the eye socket in a variety of tetrapods. During the 1980s and 1990s the HG elicited great interest in the scientific community due to its morphological and functional complexity, and from a phylogenetic point of view. A comparative approach has contributed to a better understanding of its physiology. Whereas the chemical nature of its secretions (mucous, serous or lipids) varies between different groups of tetrapods, the lipids represent the more common component among different species. Indeed, besides being an accessory to lubricate the nictitating membrane, the lipids may have a pheromonal function. Porphyrins and melatonin secretion is a feature of the rodent HG. The porphyrins, being phototransducers, could modulate HG melatonin production. The melatonin synthesis suggests an involvement of the HG in the retinal-pineal axis. Finally, StAR protein and steroidogenic enzyme activities in the rat HG suggests that the gland contributes to steroid hormone synthesis. Over the past twenty years, much has become known on the hamster (Mesocricetus auratus) HG, unique among rodents in displaying a remarkable sexual dimorphism concerning the contents of porphyrins and melatonin. Mainly for this reason, the hamster HG has been used as a model to compare, under normal conditions, the physiological oxidative stress between females (strong) and males (moderate). Androgens are responsible for the sexual dimorphism in hamster and they are known to control the HG secretory activity in different species. Furthermore, HG is a target of pituitary, pineal and thyroid hormones. This review offers a comparative panorama of the endocrine activity of the HG as well as the hormonal control of its secretory activity, with a particular emphasis on the sex dimorphic aspects of the hamster HG.

Circadian Rhythm Disruption in the Critically Ill: An Opportunity for Improving Outcomes

OBJECTIVES

Circadian rhythms are severely disrupted among the critically ill. These circadian arrhythmias impair mentation, immunity, autonomic function, endocrine activity, hormonal signaling, and ultimately healing. In this review, we present a modern model of circadian disruption among the critically ill, discuss causes of these circadian arrhythmias, review observational and intervention studies of the effects of circadian-rhythm-restoring factors on medical outcomes, and identify needed key trials of circadian interventions in the critically ill.

DATA SOURCES

MEDLINE, EMBASE, PsychINFO, Google Scholar through December 2014.

STUDY SELECTION

Articles relevant to circadian rhythms, melatonin, and light in the critically ill were selected.

DATA EXTRACTION AND DATA SYNTHESIS

Articles were synthesized for this review of circadian arrhythmia and the use of circadian-rhythm-restoring interventions among the critically ill.

CONCLUSIONS

Circadian disruption often demonstrates serial degradation: initially, the amplitude attenuates along with delayed circadian phase. With increasing acuity of illness, circadian rhythmicity may be lost entirely. Causes of chronodisruption may be environmental or internal to the patient. In particular, inadequate daytime illumination and nocturnal light pollution disrupt healthy circadian periodicity. Internal causes of circadian arrhythmia include critical illness itself and subjective experience of distress and pain. Observational studies of windowed rooms and real-time ambient lighting have found that physiologic light-dark patterns may support recovery from critical illness. Studies of early morning bright light or evening melatonin agonists have found improved rates of delirium, enhanced sleep, and lower arrhythmia prevalence. The current evidence base emphasizes that lighting and melatoninergic interventions deserve to be tested in full-scale trials.

The circadian system of patients with bipolar disorder differs in episodes of mania and depression

OBJECTIVES

Bipolar disorder is a common psychiatric disease characterized by mood disturbances with alternating episodes of mania and depression. Moreover, disturbances in the sleep/wake cycle are prevalent. We tested a hypothesis that the function of the circadian system, which drives the sleep/wake cycle, may differ in patients with bipolar disorder depending on whether they are experiencing an episode of mania or depression.

METHODS

To assess the functional state of the central circadian clock, daily profiles of melatonin levels in saliva were determined. The functional state of the peripheral clocks was assessed by determining daily profiles of Per1 and Nr1d1 clock gene expression in buccal mucosa cells. Sixteen patients with bipolar disorder in a manic episode, 22 patients in a depressive episode, and 19 healthy control subjects provided samples at regular intervals during a 24-hour cycle.

RESULTS

During episodes of mania, the daily profiles of melatonin differed compared with healthy controls and patients in an episode of depression, mainly due to elevated melatonin levels during the daytime. No difference was found between melatonin profiles of control subjects and patients in depression. The Per1 and Nr1d1 profiles were advanced in patients in mania compared with those in depression. Compared with controls, a trend toward an advance was apparent in the profiles of patients during an episode of mania but not depression. The amplitude of the Nr1d1 expression profile was higher in mania than in depression.

CONCLUSIONS

The data revealed differences in the functional state of the circadian system in patients with bipolar disorder depending on whether they were experiencing a manic or a depressive episode.

Diazepam affects both level and amplitude of rat locomotor activity rhythm but has no effect on core body temperature

The present study investigates the effects of a chronic administration of diazepam, a benzodiazepine widely used as an anxiolytic, on locomotor activity and body core temperature rhythms in male Wistar rats housed under 12 : 12 light : dark (LD) cycle conditions. Diazepam was administered subcutaneously for 3 wks in a dosage of 3 mg/kg body weight/day, 1 h before the onset of darkness. Diazepam increased the level of locomotor activity from the first day until the end of treatment, and also increased the amplitude of the activity circadian rhythm, but only on the third wk of treatment. Diazepam exerted no effects on the length of the period and did not affect the phase of the locomotor activity rhythm. The body temperature rhythm of rats was affected neither by short-term (a single injection) nor by long-term (every day for 3 wks) diazepam treatment. Diazepam lacked effect on body core temperature even on the first day of administration, thereby ruling out the possibility of drug tolerance development. The fact that diazepam affects locomotor activity, but not core body temperature, suggests that different mechanisms mediate the actions of diazepam on locomotor activity and on core body temperature.

Inversion of melatonin circadian rhythm in chronic alcoholic patients during withdrawal: preliminary study on seven patients

AIMS

The inversion of melatonin circadian rhythm secretion in some alcoholics during both intake and acute withdrawal has been widely reported. In the same way, what happens to this inversion when these patients are in long-term withdrawal is not known. To document this abnormality in alcoholics after withdrawal we investigated melatonin secretion observed during chronic alcoholization and after withdrawal.

METHODS

We measured the urinary 6-sulfatoxymelatonin (6SM) (6SM/creatinine ratio), main metabolite of the hormone, in two fractions, one diurnal and the other nocturnal, in seven alcohol-dependent patients presenting with this abnormality during alcoholization at two times: in acute withdrawal phase (under benzodiazepines) and 15 days after beginning of withdrawal (free of any psychotropic treatment).

RESULTS

Our results show that this reversed rhythm of melatonin secretion as seen by the diurnal excretion of 6SM (6SM/creatinine ratio) persists during acute withdrawal in more than half of the patients and is still present 15 days after withdrawal in three patients.

CONCLUSION

It is remarkable that the inversion of the melatonin rhythms gets corrected in four out of seven patients after withdrawal. But, the circadian disorganization of melatonin secretion in three patients could underline a desynchronization in some alcoholic patients and may indicate more widespread circadian temporal structure disturbances in these patients.

Effect of melatonin and diazepam on the dissociated circadian rhythm in rats

The main structures involved in the circadian system in mammals are the suprachiasmatic nuclei (SCN) of the hypothalamus. The SCN contain multiple autonomous single-cell circadian oscillators that are coupled among themselves, generating a single rhythm. However, under determined circumstances, the oscillators may uncouple and generate several rhythmic patterns. Rats exposed to an artificially established 22-h light-dark cycle (T22) express two stable circadian rhythms in their motor activity that reflect the separate activities of two groups of oscillators in the morphologically well-defined ventrolateral and dorsomedial SCN subdivisions. In the experiments described in this paper, we studied the effect of melatonin and diazepam (DZP) administration in drinking water on the dissociated components of rat motor activity exposed to T22, to deduce the possible mechanism of these drugs on the circadian system. In order to suppress the endogenous circadian rhythm of melatonin, in some of the rats the pineal gland or the superior cervical ganglia were removed. The results show that melatonin or DZP treatment increased the manifestation of the light-dependent component to the detriment of the manifestation of the non-light-dependent component and that melatonin, but not DZP, shortens the period of the non-light-dependent component. These findings suggest that both DZP and melatonin favor entrainment to external light, and that melatonin could also act on the SCN, producing changes in the period of the circadian cycle.

Ex vivo studies on the acute and chronic effects of DHEA and DHEA-sulfate on melatonin synthesis in young- and old-rat pineal glands

This study investigates the effects of acute and chronic injections of the neurosteroid dehydroepiandrosterone (DHEA) and its sulfate DHEA-S on pineal gland melatonin synthesis. Pineal melatonin production and plasma melatonin levels were investigated in young (9-week-old) and old (27-month-old) male Wistar rats. DHEA or DHEA-S have been administered acutely in a single intraperitoneal injection at a dosage of 50, 250, or 500 microg per animal, or on a long-term basis, i.e., for 8 days at a dosage of 100 microg per animal, 1 h before the onset of darkness. DHEA, at a dose of 50, 250, or 500 microg per animal, administered acutely to rats had no significant effects on pineal melatonin production whatever the age of the animals. In contrast, 500 microg DHEA-S induced a significant increase in the pineal melatonin content (15% in young animals and 35% in old animals) and the activity of N-acetyltransferase, the rate-limiting enzyme for melatonin synthesis in the pineal gland, (40% in young animals and 20% in old animals), without altering the activity of hydroxyindole-O-methyltransferase whatever the age of the animals. At lower concentrations (50 or 250 microg) DHEA-S had no effect on pineal melatonin production regardless of the age of the rats. Chronic injection of DHEA or DHEA-S at a dose of 100 microg had no effect on pineal melatonin or NAT and HIOMT activities in the two age groups. This work shows that DHEA-S (and not DHEA) is able, at pharmacological concentrations, to stimulate melatonin production by rat pineal glands regardless of the age of the animals.