Short-term REM sleep deprivation effect on temperature rhythm of rats.

Circadian rhythm of body temperature (CRT) is altered in endogenous depression and many psychiatric disorders. Even the sleep pattern is disrupted. Sleep deprivation alleviates symptoms in depression. The present study was conducted to find the role of noradrenergic innervation to the pineal gland in bringing about the effect of REM sleep deprivation (REMSD) on the CRT. Adult male Wistar rats (n = 12) divided into 2 groups were used for the study. The group I rats (n = 6) underwent superior cervical ganglionectomy and the group II rats (n = 6) were sham ganglionectomised. After recovery rats were given REMSD for 48 hours. The CRT was measured in three periods of the study i.e. basal, post operative and post REMSD. The results indicated REMSD increased the Amplitude and Mesor of the CRT in both the groups which was shortlasting and reversible thus suggesting non sympathetic mediation of the pineal in bringing about the circadian rhythm alteration due to REMSD.

Superior cervical ganglionectomy leads to dampening of amplitude of temperature rhythm in rats.

The circadian rhythm of body temperature (CRT) is a robust marker of the endogenous pacemaker function and is one of the most frequently studied rhythms. Melatonin, the main secretion of the pineal gland seems to have more of a thermomodulatory role in controlling the body temperature than having a direct role in thermoregulation. The sympathetic innervation to the pineal via the superior cervical ganglion determines the melatonin secretion, and superior cervical ganglionectomy (SCGx) decreases the secretion of melatonin. The present study was conducted on the Wistar rats (n = 12) to determine the role of melatonin in modulation of CRT. Adult male rats were either ganglionectomised (n = 6) or sham ganglionectomised (n = 6). Rectal temperature was recorded for CRT analysis. Cosinar analysis of the temperature record was done to get the acrophase, amplitude and mesor. Our results show that SCGx decreases the amplitude to the rhythm but has no effect on the mesor of the rhythm. Our study confirms that melatonin has little role to play in the thermoregulation and its role is mainly in thermomodulation.

Certain immunological parameters in subacute cold stress.

The effect of subacute cold swimming stress on the immune system of albino rats was investigated. Subacute cold stressed animals showed an increase in total WBC count, eosinophils and basophils. Phagocytic index and avidity index were also increased indicating hyperactive phagocytic process. On the other hand NBT reduction and soluble immune complex levels decreased significantly in stressed animals. There were no significant changes in the weight of the lymphoid organs.