Anterograde nerve degeneration after superior cervical ganglionectomy coexists with a decrease in arginine vasopressin release in rats.
After bilateral superior cervical ganglionectomy (SCGx) in adult male rats, norepinephrine content of the pituitary neurointermediate lobe (NIL) 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 NIL-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. NIL-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 NIL at 16-24 h after surgery. The changes in plasma and NIL-AVP levels found 6 or 16 h after SCGx or sham SCGx were unaffected by a prior pinealectomy. Two injections of the alpha 1-adrenoceptor blocker prazosin 45 and 90 min before sacrifice, alone or together with the beta-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 NIL-AVP found 16 h after SCGx.(ABSTRACT TRUNCATED AT 250 WORDS)
Romeo
H E
HE
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Spinedi
E
E
Esquifino
A I
AI
Estivariz
F
F
Cardinali
D P
DP
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000502:physiology*; D015171:Ganglionectomy; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D010904:Pituitary Gland, Posterior / Q000378:metabolism*; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014855:Wallerian Degeneration / Q000502:physiology*
D001127:Arginine Vasopressin; D011433:Propranolol; D011224:Prazosin