Morphometric and functional changes of female rat pituitary somatotropes after central application of somatostatin

This study examined the effects of intracerebroventricularly (i.c.v.) admin istered somatostatin (SRIH-14 or SRIH-28) on growth and function of pituita ry somatotropes (GH cells). Female rats were subjected to intracerebroventr icular administration of three Ig doses of SRIH-14 or SRIH-28 every second day. Blood samples were collected for hormone analyses and pituitaries were removed for histological and morphometric evaluation, five days after the last injection. Compared to control animals, SRIH treatment decreased (p<0. 05) ail morphometric measurements obtained for GH cells. The concentration of serum growth hormone (GH) in SRIH-14- or SRIH-28-treated groups was lowe r (p<0.05) by 69% and by 61% respectively, in comparison to control rats. T hese findings suggest that centrally administered somatostatin is specifica lly involved in the control of growth and secretory activity of GH cells. T hus, pharmacological manipulation of SRIH receptors reached from cerebrospi nal fluid may alter the systemic effects of GH.