MORPHOMETRIC AND FUNCTIONAL-CHANGES OF RAT PITUITARY SOMATOTROPES ANDLACTOTROPES AFTER CENTRAL ADMINISTRATION OF SOMATOSTATIN

This study examined effects of intracerebroventricularly (i.c.v.) admi nistered somatostatin (SRIH-14 and SRIH-28) on growth and function of pituitary somatotropes (GH cells) and lactotropes (PRL cells), Male ra ts received three i.c.v. injections (1 mu g/5 mu l) of SRIH-14 or SRIH -28 every second day, Blood samples were collected for hormone assays and pituitaries were removed for histological and morphometric evaluat ion 5 days after the last i.c.v. treatment, Compared to control animal s, SRIH treatment decreased (p < 0.05) pituitary weight and all morpho metric measurements obtained in GH and PRL cells, Concentrations of se rum growth hormone (GH) and prolactin (PRL) in both SRIH-treated group s were also lower (p < 0.05) than in control rats, These findings sugg est that centrally administered somatostatin is specifically involved in the control of growth and secretory activity of GH and PRL cells, T hus, pharmacological manipulation of SRIH receptors reached from cereb rospinal fluid may alter systemic effects of GH and PRL.