Increase in Adrenocorticotropin Release during Wallerian Degeneration of Peripheral Sympathetic Neurons after Superior Cervical Ganglionectomy of Rats

Abstract

The changes in adrenocorticotropin (ACTH) release before, during and after sympathetic nerve degeneration following superior cervical ganglionectomy (SCGx) were examined in male rats. A 12-fold increase of circulating ACTH was found in both SCGx and sham-operated rats 6 h after surgery. In sham-operated rats, plasma ACTH decreased by about half 16–22 h after surgery, whereas in SCGx rats it remained at a high concentration from 16 to 54 h after surgery, attaining basal values by 120 h post-SCGx. In SCGx rats, MBH corticotropin-releasing hormone (CRH) content decreased significantly from 16 to 54 h after surgery, while in controls it remained unmodified. Significantly smaller arginine vasopressin (AVP) contents were found in MBH of SCGx rats as compared to sham-operated controls, 16–54 h after surgery. In rats exposed to ether or immobilization stress 22 h after SCGx, plasma ACTH levels were significantly higher than in controls; however, since unstressed ACTH levels were about twice as high in SCGx rats, the percent increase of ACTH was smaller in the SCGx group. A decreased response of plasma ACTH to ether or immobilization stress was found in rats 7 days after SCGx. In rats subjected to a simultaneous adrenalectomy (Adx) and SCGx or sham-SCGx, plasma ACTH levels increased to a similar extent in both groups. ACTH increase after Adx was accompanied by decreases in MBH CRH, and absence of significant changes in MBH AVP contents. Rats subjected to pinealectomy (Px) or sham-Px 1 week earlier and killed 22 h earlier exhibited similar responses in plasma ACTH and MBH CRH to SCGx regardless of pineal intactness. These results demonstrate a stimulatory, pineal-independent, effect on ACTH release of wallerian degeneration of nerve fibers in the superior cervical ganglia field of projection.

Superior Cervical Ganglionectomy Effects on Median Eminence and Anterior and Mediobasal Hypothalamic Taurine Content in Male Rats: Effects of Hyperprolactinemia

“…Differentially plasma ACTH levels increased during wallerian degeneration of the adrenergic terminals after superior cervical ganglionectomy, as shown by earlier work in the literature [30]. After chronic surgery no changes in plasma prolactin and GH levels were observed, as in previous studies [4,9].…”

Anterograde Nerve Degeneration after Superior Cervical Ganglionectomy Coexists with a Decrease in Arginine Vasopressin Release in Rats

“…It must be noted that as far as surgical stress was concerned, precautions were routinely taken in the present experiments to introduce the same type of stress in both the experimental and sham-operated groups, except for ganglion removal. That the resulting surgical stress was presumably the same in SCGx and sham SCGx rats was indicated by a similar increase in plasma ACTH levels and a similar hypothalamic concentration of CRH and AVP reported in both groups of animals 6 h after surgery [21 ].…”

“…The results ob tained indicate that a prior Px did not modify the changes in AVP release found 6 or 16 h after SCG ablation. Thus, as in the case of gonadotropin [23], prolactin [23] and ACTH re lease [21], SCG neurons modify AVP release from NIL by a mechanism independent of the pineal gland, most presum ably linked to an intrapituitary effect.…”

Neuroimmunoendocrinology of the cervical autonomic nervous system

“…In a study designed to examine the levels of serum growth hormone (GH) and PRL, and of MBH GH-releasing hormone (GHRH), thyrotropin-releasing hormone (TRH) and somato-statin, from 16 h to 7 days after bilateral SCGx of adult male rats (35) we reported significantly lower serum GH and PRL, and higher MBH GHRH and TRH levels as compared to controls during the Wallerian degeneration phase; MBH somatostatin concentration decreased in SCGx rats. The data, together with the previously observed decrease in MBH corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) content found in SCGx rats during the Wallerian degeneration phase (36), as well as with the LHRH data mentioned above, indicated that a modulator/ role of peripheral sympathetic nerve terminals is exerted on hypophysiotropic hormone release. A previous Px did not modify the changes in hypophysiotropic or hypophyseal hormone release found during the Wallerian degeneration phase after SCGx.…”