Morphine administration and abrupt cessation alter the behavioral diurnal activity pattern.

In mammals, there is an underlying mechanism that dictates the organism's biological functions and daily activity schedule, known as circadian rhythms, which play a major role in maintaining steady metabolism, homeostasis, and immunity. Limited research has been done investigating the effects of continuous opiate administration on the circadian rhythm activity pattern. A change in circadian activity pattern is suggested as an experimental model to demonstrate long-term effect of the drug.

Interferon modulates central nervous system function.

The interferons (IFNs) are an endogenous pleiotropic family of cytokines that perform fundamental physiological functions as well as protecting host organisms from disease and in maintaining homeostasis. This review covers the effects of endogenous IFN on the nervous system. It starts with the description of its receptors, followed how it modulate neuronal activity, mood, sleep, temperature, the endocrine system, the opioid system and how it regulate food consumption and the immune system.

Melatonin attenuates the decrement of dendritic protein MAP-2 immuno-staining in the hippocampal CA1 and CA3 fields of the aging male rat.

Neuronal death during brain aging results, at least in part, from the disruption of synaptic connectivity caused by oxidative stress. Synaptic elimination might be caused by increased instability of the neuronal processes. In vitro evidence shows that melatonin increases MAP-2 expression, a protein that improves the stability of the dendritic cytoskeleton, opening the possibility that melatonin could prevent synaptic elimination by increasing dendritic stability.