EFFECTS OF PORCINE GROWTH-HORMONE ON PREGNANCY AND FETAL NEONATAL DEVELOPMENT IN THE RAT

Porcine growth hormone was given subcutaneously twice dally to two gro ups of 20 females at dose levels of 0.5 and 2.5 IU/kg (1 and 5 IU/kg/d ay). A control group of 20 females was similarly treated with vehicle. The females were given either vehicle or porcine growth hormone from gestation day (GD) 6 through GD 21, for 10 females that were cesarean sectioned, or through lactation day (LD) 21, for 10 females scheduled for natural delivery. There were no deaths, abortions, or drug-related physical signs in any treatment group. Drug-related effects during ge station were limited to significant (p less than or equal to 0.05) pha rmacologically mediated increases in F-0 maternal body weight gain dur ing GD 6-20 in the 2.5-IU/kg group, approximately 24% above controls. During LD 0-21, there were significant(p less than or equal to 0.05) d ose-related increases in average maternal body weight gain in the 0.5- and 2.5-IU/kg groups (72 and 200% above controls, respectively). Cons istent with these findings, there were dose-dependent increases in mat ernal serum growth hormone and IGF-1 levels noted on GD 21 and LD 21 i n both drug-treated groups. There were no drug-related effects on embr yonal/fetal survival, GD 21 fetal body weight, placental weight, fetal femur length and width, or fetal morphology as determined by external , visceral, and skeletal examinations. There were no drug-related effe cts on F-1 pup mortality, physical signs, body weight, biparietal diam eter, liver weight, and femur length or width. These data suggest that subcutaneous administration of growth hormone to pregnant and lactati ng rats, at a dose that produces significant (p less than or equal to 0.05) increases in maternal body weight gain and serum IGF-1 levels, h as no apparent effect on embryonal/fetal development or preweaning gro wth.