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

Abstract

After bilateral superior cervical ganglionectomy (SCGx) in adult male rats, norepinephrine content of the pituitary neurointermediate lobe () decreased at 12–24 h after surgery to attain concentrations 40–60% of controls between 24 and 60 h after surgery. To assess arginine vasopressin (AVP) secretion during this time, plasma and -AVP levels were measured by radioimmunoassay. In sham SCGx controls, plasma AVP increased about 2-fold within 6 h after surgery and decreased thereafter, to attain presurgical values by 60 h after surgery. In SCGx rats, a significant increase in plasma AVP concentration was observed at the 6th h after surgery, as compared to presurgical concentrations, with a decrease to values significantly lower than those of presurgical controls at 16–18 h after SCGx. As compared to sham-operated rats, significantly higher plasma AVP levels 6 h after surgery and significantly lower plasma AVP levels 16–24 h after surgery were found. -AVP concentration in SCGx and sham-operated ras were significantly lower than presurgical levels at 6 h after surgery. SCGx rats had significantly higher amounts of AVP in at 16–24 h after surgery. The changes in plasma and -AVP levels found 6 or 16 h after SCGx or sham SCGx were unaffected by a prior pinealectomy. Two injections of the α₁-adrenoceptor blocker prazosin 45 and 90 min before sacrifice, alone or together with the β-blocker propranolol, prevented the increase in plasma AVP found in SCGx rats 6 h after surgery, and the decrease in plasma AVP and the increase of -AVP found 16 h after SCGx. Propranolol treatment did not modify AVP levels. Neither drug was effective to modify AVP levels in sham-operated controls. The results argue in favor of physiologically relevant projections from superior cervical ganglion neurons to the neurohypophysis which participate in control of AVP release.

Acute and Chronic Effects of Superior Cervical Ganglionectomy on in vitro Mitogenic Responses of Lymphocytes from Submaxillary Lymph Nodes of Pituitary-Grafted Rats

“…In rats, norepinephrine content of the submaxillary lymph nodes starts to decrease 6-10 h after SCGx and reaches its lowest concentration (about 5% of normal) approximately 24-30 h after surgery [14,25]. The degeneration reaction paradigm has been useful for defining the role of peripheral sympathetic nerves in neuroendocrine control [15][16][17][18][19]26].…”

“…These times were selected to cover both the chronic deprivation sequelae of SCGx and the transient postsynaptic activation that occurs during the early phase of anterograde ('wallerian') degeneration of SCG nerve endings in SCGx animals [13][14][15]. Such a complementary approach has enabled us to analyze the neuroendocrine consequences of an increased or decreased postsynaptic exposure to adrenergic transmitter in the thyroid [16] and parathyroid glands [17], the median eminence [18] and the posterior pituitary [19].…”

Involvement of the Cervical Sympathetic Nervous System in the Changes of Calcium Homeostasis during Turpentine Oil-Induced Stress in Rats

“…In experiment 2, rats received a bilateral SCGx or a sham oper ation under ether anesthesia as described elsewhere [20,21]. Two weeks after surgery, the animals were injected subcutaneously with turpentine oil (5 ul/g body weight) or vehicle, and were subjected to the hypocalcémie or hypercalcémie tests described above 4 h later.…”

Neuroimmunoendocrinology of the cervical autonomic nervous system

“…Other areas anatomically related to the median eminence become partiallydenervated after SCGx. This is the case of the neurointermediate lobe, whose NE fibers are in part peripheral, as shown by the 40% decrease of posterior pituitary NE content after SCGx (29). a 1-adrenoceptor binding sites, autoradiographically detectable in the neural lobe of the rat pituitary, increased in number after SCGx, but not after pituitary stalktransection, thus indicating their association with peripheral NE-containing fibers (30).…”