Effects of Continuous Light and Darkness, and of Pinealectomy, Adrenalectomy and Gonadectomy on Uptake of ³H-Serotonin by the Suprachiasmatic Nuclear Region of Male Rats

Abstract

Rats exposed to continuous light show no significant differences in serotonin (5-HT) uptake by the suprachiasmatic nuclear region (SNR) at 10.00 and 22.00 L, while in continuous darkness, the uptake at 10.00 D is significantly higher than uptake at 22.00 D. In consideration of the role of the suprachiasmatic nucleus in light-mediated control of neuroendocrine activity, this suggests endogenous generation or control of this uptake rhythm. An effect of sham-pinealectomy in decreasing 5-HT uptake was found, but cannot be fully interpreted at this time. The lack of effect of castration or adrenalectomy suggests that these endocrines have little if any direct effect on 5-HT mechanisms in the SNR.

Influence of the pineal and melatonin administration on the day‐night changes in the adrenal catecholamines of young chicks

“…Compared to the fluctuation of adrenal E in Con and NO-V birds, a loss of the nocturnal elevation of E was noted in the adrenals of SO-V chicks. Similar to this finding, effects of shampinealectomy long after surgery have been reported by several authors (Meyer and Quay, 1976;Gorray and Quay, 1978;Banerji et al, 1980;Kachi et al, 1979Kachi et al, , 1980Banerji and Quay, 1986). Although the underlying mechanism for the effects of sham-pinealectomy on adrenal catecholamines remain to be elucidated, it might be that the surgical stress or trauma has repercussions on the adrenomedullary nerve endings (Kachi et al, 1988).…”

Effects of Melatonin on Adrenomedullary Dopamine‐β‐Hydroxylase Activity in Golden Hamsters: Evidence for Pineal and Dose Dependencies

“…It remains possible, therefore, that these two tissue components are affected differently under various surgical manipulations of the pineal and/or melatonin adminstration. This is clearly suggestive from our present experiment in which the shamoperated group receiving a low dose of melatonin had significantly lower adrenal DBH activity compared to the matched PX group (i.e., PX + 25 pg melatonin) although the changes in adrenal weight were not significantly different [Quay et al, 19821. Diverse effects of sham-pinealectomy long after surgery and after all overt sequelle of the operation had disappeared have been reported in recent years [Meyer and Quay, 1976;Gorray and Quay, 1978;Banerji et al, 19801. For example, in many cases, sham-pinealectomy and pinealectomy have been found to produce similar results. A plausible explanation for this has been provided by Frowein and Lapin [1979] who found that surgery performed under strong white light led to a long-lasting depression in pineal content of melatonin in rats.…”

Differential effects of photoperiod and temperature on hypothalamic monoaminergic activity in the teleost Channa punctatus (Bloch)

“…Hypothalamic 5-HT activity has been related to photosexual responses in mammals (Meyer and Quay 1976) and birds (Elhalawani et al 1978), the control of endocrine rhythms (Kordon et al 1978;Scapagnini et al 1978) and to the transmittance of day-night information in ferrets (Yates and Herbert 1976). A hypothalamic serotonergic system is implicated in the regulation of the secretion of prolactin (Olivereau 1978a;James and Wigham 1984), MSH (Olivereau 1978b) and gonadotropin (Groves 1984) from the pituitary of teleosts; all of which are influenced by environmental light regimes.…”

“…In higher vertebrates, hypothalamic monoamines are implicated in the control of endocrine rhythms (Kordon et al 1978;Scapagnini et al 1978). Circadian activity of hypothalamic serotonin (5-HT) is related to transmission of day length information in ferrets (Yates and Herbert 1976) and a serotonergic mechanism is suggested to be involved in photosexual responses in mammals (Meyer and Quay 1976) and birds (Elhalawani et al 1978).…”