Effect of Superior Cervical Ganglionectomy on 24‐h Variations in Hormone Secretion from the Anterior Hypophysis and in Hypothalamic Monoamine Turnover During the Preclinical Phase of Freund's Adjuvant Arthritis in Rats

Abstract

The effect of superior cervical ganglionectomy (SCGx) on 24-h rhythms of circulating adrenocorticotropic hormone (ACTH), growth hormone (GH), prolactin and luteinizing hormone (LH) and of hypothalamic noradrenaline content and dopamine and serotonin turnover, was assessed in rats 3 days after administering Freund's complete adjuvant. In sham-operated rats, Freund's adjuvant injection increased serum ACTH without affecting its diurnal rhythmicity. SCGx, performed 10 days earlier, suppressed 24-h rhythmicity and augmented mean values of circulating ACTH. A depressive effect of immunization on GH release was found in both sham-operated and SCGx rats. GH concentrations did not exhibit diurnal rhythmicity and decreased after immunization. Time-of-day-related changes in serum prolactin were significant for all examined groups, except for SCGx-immunized rats. Freund's adjuvant administration augmented prolactin secretion. Daily changes in serum LH concentration and a decrease after immunization were found in both sham-operated and SCGx rats. SCGx: (i) counteracted inhibition of daily variations of noradrenaline content in medial hypothalamus of Freund's adjuvant-injected rats; (ii) decreased anterior hypothalamic dopamine turnover and augmented it in the medial hypothalamus; (iii) lowered amplitude of serotonin turnover rhythm in medial hypothalamus. The data indicate that several early changes in levels and 24-h rhythms of circulating ACTH and prolactin, and in hypothalamic noradrenaline content and dopamine and serotonin turnover, were modified by a previous SCGx in Freund's adjuvant-injected rats.

Age-Dependent Changes in 24-Hour Rhythms of Thymic and Circulating Growth Hormone and Adrenocorticotropin in Rats Injected with Freund’s Adjuvant

“…Our results were compatible with significant effects of immunemediated inflammatory response on hormone secretory processes, which were partially sensitive to immunosuppression by cyclosporine [24][25][26]. These as well as other studies indicated that significant changes in 24-hour rhythms did occur during experimental arthritis in rats [27][28][29][30][31][32][33][34][35]. As a continuation of those experiments, we hereby describe the 24-hour changes in thymic and serum concentration of GH and ACTH and their correlation with thymic concentrations of glutamate, aspartate, taurine and GABA (as indexes of thymic metabolism) in young and old rats during the acute phase of adjuvant's arthritis.…”

Assessment of Circulating Hormones in Regulatory Toxicity Studies II. Male Reproductive Hormones

“…However, this secretion pattern has not been clearly demonstrated in male rats. Although the data are not always consistent, some reports indicate that PRL release in rats is dependent on the time of day (Castrillon et al 2001;Esquifino et al 2004;Garcia-Bonacho et al 2000). In contrast, a study by O'Connor, Van Pelt et al (2000) that was performed using rats with indwelling catheters for blood collection (and thus presumably decreasing the potential for stress-induced effects on PRL from the blood collection) found no differences in PRL concentrations as a result of the time of blood collection.…”

Is the Use of Growth hormone and Melatonin Justified in Spinal Cord Injuries?

“…Therefore, the loss, or decrease, of these adrenergic signals to the pineal gland must affect the production of MT. In fact, superior cervical ganglionectomy in rats induces early changes in 24-h rhythms and in hypothalamic content of noradrenaline [32]. For years it has been considered that MT simply acted as a synchronizer of the sleep-wake rhythm.…”