Melatonin: A Review

October 9, 2015

Melatonin is an endogenous neurohormone found in animals, plants, fungi and bacteria that serves as a modulator in the nervous system and as an important neural antioxidant. In animals, it is a hormone that anticipates the daily onset of darkness; thus, the hormone can be used as a sleep aid and in the treatment of some sleep disorders as an anti-stress agent. Results of a series of original investigations devoted to the antidepressant, anxiolytic, and nootropic activity of the pineal hormone melatonin are summarized. It is established that a decisive role in this activity belongs to the chronotropic properties of melatonin.

As stated, in animals, melatonin is involved in the synchronization of the circadian rhythms of physiological functions including sleep timing, blood pressure regulation, seasonal reproduction and many others. Many of melatonin’s biological effects in animals are produced through activation of melatonin receptors, while others are due to its role as a pervasive and powerful antioxidant, with aparticular role in the protection of nuclear and mitochondrial DNA.

As you might already know, sleep deprivation has been shown to induce oxidative stress (neuronal death, reactive astrogliosis, memory impairment and cognitive dysfunctions) which causes cognitive impairment. Melatonin, an endogenous potent antioxidant, protects neurons from oxidative stress in many disease models. This 2013 study investigated the effect of melatonin against sleep deprivation-induced cognitive impairment and attempted to define the possible mechanisms involved. Melatonin (15 mg/kg) was administered to the rats via intraperitoneal injection. The possible mechanism may be attributed to its ability to reduce oxidative stress and increase the levels of CaMKII and BDNF in CC and hippocampus. Thus, while prolonged sleep deprivation could lead to profound negative health consequences, such as impairments in vital biological functions of immunity and cognition, it can be stated that melatonin possesses powerful ameliorating effects against those harmful insults.

Moreover, in this study, treatment with melatonin attenuated the effect of propoxur (a powerful neurotoxic carbamate pesticide) on oxidative stress. The results of the study showed that melatonin has the potential to attenuate cognitive dysfunction and oxidative stress induced by toxicants like propoxur, which has been shown to adversely affect memory and induce oxidative stress on both acute and chronic exposure. Thus, melatonin has strong antioxidant and anti-inflammatory effects that help to restore body’s immune and cognitive functions.

Furthermore, it seems that melatonin could contribute to nootropics’ efficiency. In this study, The pineal hormone melatonin (0.1 mg/kg) differently changed the behavioral shifts induced by piracetam, bilobil, and ginseng in the open-field and elevated plus-maze tests in rats. Melatonin more effectively optimized memory in the model of passive avoidance conditioned reflex. It is suggested that the observed enhancement of the specific activity of nootropic drugs is related to the melatonin-induced changes in the hippocampal activity.

Pineal hormone melatonin stabilizes mental activity of man and animals due to its somnogenic, anxiolytic, antidepressant and nootropic properties. Melatonin effects are based on the synchronization of biological rhythms via the influence on the cerebral structures which control biological rhythms and emotions and normalize endocrine and immune state

Thus, these results suggest that melatonin administration might improve the cognitive abilities, at least partially, by reducing the age-related degeneration of basal forebrain cholinergic neurons. So far, a safe supplement you can take to boost nootropic action and sleep quality.