VASOPRESSIN STIMULATES DNA-SYNTHESIS IN CULTURED RAT HEPATOCYTES

Liver regeneration following partial hepatectomy is significantly impa ired in rats with hereditary vasopressin (AVP) deficiency. This sugges ted that AVP might have a direct effect on cultured rat hepatocytes. H epatocytes from male Sprague-Dawley rats were isolated using a two-ste p collagenase perfusion technique and plated at a density of 10(5)/16- mm Primaria plate. After a suitable attachment period, hepatocytes wer e incubated with minimal essential media, AVP, AVP plus a specific AVP antagonist, or oxytocin. Hepatocyte proliferation was measured by [H- 3]thymidine incorporation ([H-3]Thy) into hepatocyte DNA. AVP (10 nM) increased [H-3]Thy significantly (and this effect was blocked by an AV P-specific antagonist (50 nM). Oxytocin had no effect on hepatocyte DN A synthesis. To further investigate the influence of AVP on hepatocyte proliferation, the effect of AVP on transforming growth factor-alpha (TGF-alpha)-stimulated hepatocyte proliferation was also studied. This combination was chosen based on the ability of AVP to inhibit the bio logic effects of EGF (alpha TGF-alpha analog). There was significant a ttenuation of TGF-alpha (50 nM)-stimulated [H-3]Thy in the presence of AVP (10 nM). In summary: (1) AVP stimulates proliferation of cultured rat hepatocytes. (2) The effect of AVP can be significantly abolished by a specific AVP antagonist. (3) The proliferative response of AVP i s specific. (4) AVP significantly attenuates TGF-alpha-stimulated hepa tocyte hepatic DNA synthesis. Further studies should elucidate the mec hanisms for the effects of AVP on hepatic proliferation alone or in co mbination with Other factors. (C) 1994 Academic Press, Inc.