Investigation of Dose-Related Effects of Carnosine on Anxiety with Sympathetic Skin Response and T-maze

Abstract

Carnosine is a dipeptide formed of the amino acids β-alanine and histidine. Only a limited number of studies have examined the effects of carnosine on sympathetic nerve activation and anxiety. The present study was undertaken to determine the dose-related effects of carnosine on anxiety in the elevated T-maze test (ETM) with electrodermal activity (EDA). Carnosine was injected in three groups of rats with doses of 10 (low dose), 100 (medium dose) and 1000 (high dose) mg/kg i.p. Physiological saline was injected in the sham group. The anxiety scores of the rats were measured with ETM 20 minutes after injection. Then, SCL was measured. The decreased number of entries into the open arm (NEOA), the percentage of time spent in the open arm (% TSOA) and higher EDA [shown by skin conductance level (SCL)] indicate higher anxiety. The NEOA and % TSOA were lower in the high-dose group than in the other groups. SCL was lower in the medium-dose carnosine group than in the high-dose carnosine and sham groups. SCL was higher in the high-dose group than in the medium-dose and sham groups. Our results suggest that high-dose carnosine produced anxiety-like effects as assessed in the SCL and ETM. Medium-dose carnosine acted as an anxiolytic. The anxiety-related responses of carnosine depend on its dose-related effect.

The Potential of Carnosine in Brain-Related Disorders: A Comprehensive Review of Current Evidence

“…Administration of high dose carnosine was also shown to preserve aging-induced down regulation of the serotonergic system in specific brain regions implicated in the regulation of mental function and mood [130]. The effects of carnosine on mood may depend on dosage as shown in a study of rodents injected with different doses of carnosine, where higher doses produced anxiety-like effects and medium-doses had anxiolytic effects [131]. Acute administration of carnosine as well as chicken breast extract (where carnosine is one of the major components) decreased immobility time in a forced swimming test in rats, which is an index of depression-like behaviour.…”

Investigation of dose related effects of propolis on anxiety and some biochemical parameters with sympathetic skin response and increased T-maze

“…They occurred at pseudorandom intervals ranging from 30 s to 65 s and averaging 45 s. The mean SCL values were also calculated offline for phasic EDA. Values of phasic SCL averaged at 10 rats per group during the test period, which used 15 auditory stimuli [9]. Procedure The animals were conscious during the recordings.…”

“…Two observers recorded the number of times spent in the open and closed arms and the number of entries into each arm during a 5-minute period. The percentage of time spent in the open arms and the number of entries into these arms were used to measure anxiety [9].…”

“…The relationship between anxiety and sympathetic skin response (SSR), in other words, SCL, has been widely studied. The results of studies on human subjects and animals indicate that anxious subjects have greater sweat gland activity [9,10]. However, data are limited in animals.…”

“…It is generally known that anxiolytic drugs increase the number of entries in open arms (OAEs) and the time spent in there (TSOA), while the anxiogenic drugs decrease these parameters. Certain pharmacological compounds may affect anxiety-related behaviors depending on the dose [9].…”