Related Experiment Video
Updated: May 30, 2026

A Chronic Sleep Fragmentation Model using Vibrating Orbital Rotor to Induce Cognitive Deficit and Anxiety-Like Behavior in Young Wild-Type Mice
Published on: September 22, 2020
Melatonin attenuates cognitive dysfunction and reduces neural oxidative stress induced by phosphamidon
Amit K Sharma1, Ashish K Mehta, Naveen Rathor
1Department of Pharmacology, University College of Medical Sciences, University of Delhi, Delhi 110095, India.
Abstract:
Melatonin is an important modulator of nervous system functioning and important neural antioxidant. Organophosphate pesticides like phosphamidon (PHOS) have been shown to adversely affect memory and induce oxidative stress on both acute and chronic exposure. This study was designed to explore the modulation of the effects of PHOS on cognitive function by melatonin (MEL). Cognitive function was assessed using step-down latency (SDL) on a passive avoidance apparatus and transfer latency (TL) on an elevated plus maze. Oxidative stress was assessed by examining the levels of malondialdehyde (MDA) and nonprotein thiols (NP-SH) in isolated homogenized whole brain samples. The results showed a significant reduction in SDL and prolongation of TL in the PHOS (1.74 mg/kg/day; p.o.)-treated group at weeks 6 and 8 as compared to the control group. Two-week treatment with MEL (5 mg/kg/day; i.p.) antagonized the effect of PHOS on SDL as well as TL. PHOS alone produced a significant increase in the brain MDA levels and decrease in the brain NP-SH levels. Treatment with MEL attenuated the effect of PHOS on oxidative stress. Together the results showed that MEL attenuated the cognitive dysfunction and decreased oxidative stress induced by PHOS in the brain.
Related Concept Videos
Management of Insomnia
Cognitive Enhancers: Cholinesterase Inhibitors and NMDA Receptor Antagonists
Understanding Sleep
The circadian rhythm, a nearly 24-hour cycle, is deeply influenced by environmental light cues. Light exposure directly affects the hypothalamus, which in turn regulates...
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
Insufficient Sleep and Sleep Deprivation
Sleep deprivation is a more severe form of sleep loss...
Sedatives and Hypnotics Drugs: Miscellaneous Agents
Melatonin congeners like ramelteon (Rozerem) and tasimelteon (Hetlioz) selectively bind to melatonin receptors (MT1 and MT2) and thus mimic the actions of melatonin, a hormone that regulates sleep-wake cycles. Tasimelteon is primarily used for non-24-hour sleep-wake disorder, common in blind patients. They are also used to treat conditions like insomnia...

