Both melatonin and DSIP (a nine amino acid peptide) effects have been previously shown to be (a) circadian rhythm related and (b) involved in inducing hypothermic effects in rats. In this study we report the hypothermia effects by each of these drugs alone and in combination when studied in normal (unoperated), pinealectomized, and hypophysectomized rats at various time points of the corresponding circadian cycle. A clear differential effect of drugs X time X preparation was found. While both DSIP and melatonin hypothermic effects were both circadian cycle dependent in intact rats the rhythmicity of melatonin hypothermic effect in pinealectomized rats, and DSIP hypothermic effect in hypophysectomized rats was missing. Although several hypotheses have been offered to account for the physiological mechanism(s) that govern the effects of the drugs, it is not yet possible to reliably relate the findings to existing neurochemical theory.

Animals↗

PubMedDate not supplied

The facilitative effects of alpha-MSH and melanin on learning, thermoregulation, and pain in neonatal MSG-treated rats.

Administration of monosodium glutamate (MSG) in the neonatal period renders the rat to be alpha-MSH deficient later in life. In this study rats received MSG in their neonatal period and were examined at the age of 60 days. alpha-MSH caused hypothermia, potentiated induced hypothermia, blocked paradoxical behavioral thermoregulation, improved performance in the Morris water tank, but had no effect on pain threshold. Melanin only caused an increase in pain threshold. It is suggested that the differential effect of alpha-MSH and melanin is governed by the dopaminergic system.

Animals↗

PubMedDate not supplied

Circadian effects of beta-endorphin, melatonin, DSIP, and amphetamine on pentylenetetrazol-induced seizures.

Circadian effects on PTZ-induced seizure thresholds alone and following drug pretreatment were studied in 720 male rats, divided into 40 groups of 18 each. Each rat was tested only once, at one of eight clock hours and under one of five drug pretreatments. Clear cyclic changes in thresholds were found. Drug effects on the rhythm were similar for DSIP and beta-endorphin, which produced higher thresholds during the night periods, while d-amphetamine and melatonin decreased the threshold during that period. All drugs increased the vulnerability to seizures relative to the saline control during the daytime, while only beta-endorphin and DSIP offered improved protection during the night hours. The possibility of dopaminergic mediation is suggested to account for the effects.

Animals↗

PubMedDate not supplied

Mediation of cognitive function by high fat diet following stress and inflammation.

In addition to commonly advertised hazards of obesity contributed by excess dietary fat, evidence of alterations in brain chemistry and structure are well documented. This brief review examines the role of nutrients, minerals and certain lipids, primarily the essential fatty acids (FA), that are beneficial to the maintenance of good health and that may offer therapeutic options by dietary supplementation. The review also considers the damaging effects of stress, especially in pre-existing conditions of obesity and diabetes, as studied in both animals and humans. The main focus of this brief review is to examine the effects of a high fat diet on stress and the immune system with particular emphasis on brain and cognitive function.

Animals↗