Circadian Rhythm of Arginine Vasopressin in Hepatorenal Syndrome

Abstract

The etiology of hepatorenal syndrome is still incompletely understood, but the nonosmotic release of arginine vasopressin (AVP) seems to have an important role. Since AVP presents a well-defined daily periodicity in its production and secretion, the aim of the study was to investigate the circadian rhythm in its circulating plasma concentrations in patients with hepatorenal syndrome, compared with healthy controls. Venous blood samples were drawn during a 24 hour period at 2 hourly intervals from a peripheral vein in 10 healthy subjects and in 10 patients with hepatorenal syndrome for the determination of the circulating plasma levels of AVP by radioimmunoassay. Statistical analysis was carried out by the ‘cosinor’ method. The controls presented a significant (p < 0.002) circadian rhythm in the AVP circulating levels, whereas no rhythm (p > 0.05) was found in patients. The circadian rhythms were significantly (p < 0.005) different between the two groups, patients having higher mean daily concentration and lower circadian variation of AVP. These results confirm the existence of a well-defined circadian rhythm of AVP in healthy subjects, whereas the hepatorenal syndrome patients present a complete loss of the circadian rhythm. It could be hypothesized that primitive damage in circadian time-keeping regulates the circadian rhythm of vasopressinergic neurons, or has a secondary effect on the peripheral vasodilatation in the course of advanced liver disease. This great upset in the temporal and functional organization, together with that of the renin-angiotensin-aldosterone system, could play an important role in promoting and/or in the maintenance of the hydroelectrolyte imbalance that characterizes the hepatorenal syndrome.

Update on Peripheral Arterial Vasodilation, Ascites and Hepatorenal Syndrome in Cirrhosis

“…In addition, there was a positive correlation between the plasma noradrenaline and AVP concentrations after an acute water load in patients with cirrhosis (51). An absence of circadian changes in venous plasma concentrations of AVP in patients with HRS has been found and may contribute to enhanced water retention (52). The role of AVP in water retention has also been demonstrated in experimental cirrhosis.…”

Increased Expression of Tyrosine Hydroxylase Immunoreactivity in Paraventricular and Supraoptic Neurons in Illnesses with Prolonged Osmotic or Nonosmotic Stimulation of Vasopressin Release

“…The presence of increased TH expression in nonosmotically stimulated human VP neurons was also found in the PVN and SON (including its central vasopressinergic part) in all the 4 subjects of our sample who had suffered from hepatic cirrhosis. The nonosmotic baroreceptor-mediated stimulation of VP release secondary to a decrease in the ‘effective’ blood volume (or to arterial underfilling) is an important factor in the abnormal water secretion in cirrhosis, as reported by many authors [50, 58, 59, 60, 61, 62, 63, 64]. …”

Distribution of MT1 melatonin receptor immunoreactivity in the human hypothalamus and pituitary gland: Colocalization of MT1 with vasopressin, oxytocin, and corticotropin‐releasing hormone

“…In plasma and urine, AVP and OXT normally shows a circadian rhythm, with higher levels at night and lower levels during the day (Forsling et al, 1998). The circadian rhythm of AVP and OXT was presumed to result from a direct projection of the SCN to the SON in rat (Pasqualetti et al, 1998). However, such a direct connection has not been found in the human hypothalamus, although SCN fibers come close to the SON (Dai et al, 1997(Dai et al, , 1998.…”