Effects of somatostatin and urotensin II on tilapia pituitary prolactin release and interactions between somatostatin, osmotic pressure Ca++, and adenosine 3',5'-monophosphate in prolactin release in vitro

Endocrinology. 1982 Mar;110(3):910-5. doi: 10.1210/endo-110-3-910.


Both somatostatin (SRIF) and urotensin II, a dodecapeptide from the teleost caudal neurosecretory system, inhibit PRL release from the organ-cultured rostral pars distalis of the tilapia, Sarotherodon mossambicus, in a dose-related manner. The inhibitory action of SRIF on PRL release was completely prevented by the presence of the calcium ionophore A23187. PRL release was also blocked when Ca++ was excluded from the incubation medium, even in the presence of the ionophore. Both dibutyryl cAMP (dbcAMP) and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, alone or in combination, stimulated PRL release during incubation in high osmotic pressure medium. The effect of dbcAMP appeared to be dose related. Together, dbcAMP and 3-isobutyl-1-methylxanthine were also effective in preventing the inhibition of PRL release by SRIF. These results are consistent with the notion that Ca++, and possibly cAMP, may be important mediators of PRL secretion, and it is likely that SRIF may inhibit PRL release by blocking a Ca++- or cAMP-mediated mechanism.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Animals
  • Bucladesine / pharmacology
  • Calcimycin / pharmacology
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Cyclic AMP / metabolism*
  • Fishes
  • Osmotic Pressure
  • Peptides / pharmacology*
  • Pituitary Gland / drug effects
  • Pituitary Gland / metabolism*
  • Prolactin / metabolism*
  • Somatostatin / pharmacology*
  • Urotensins / pharmacology*


  • Peptides
  • Urotensins
  • Calcimycin
  • Somatostatin
  • Bucladesine
  • Prolactin
  • urotensin II
  • Cyclic AMP
  • Calcium
  • 1-Methyl-3-isobutylxanthine