Effect of maternal infusion of adrenocorticotrophin1-24 (ACTH1-24) on parturition in guinea-pigs near term.
While the mechanism of onset of labour in guinea-pigs is unknown, it has been suggested that administration of adrenocorticotrophin1-24 (ACTH1-24) near term induces labour. In order to verify this finding, guinea-pigs were fitted with indwelling carotid and jugular vascular cannulae. ACTH1-24 (30 microg h(-1) for four hours, n = 9) or vehicle (n = 5) was infused intravenously on Day 64 (term is 68 days). ACTH1-24 had no effect on gestational length (68.4+/-1.0 days, n = 6 v. control, 69.6+/-0.3 days, n = 5, P = 0.8). Symphysial width, fetal weight, number and viability were similar in both groups (all P > 0.1). Infusion of ACTH1-24 increased maternal ACTH concentrations from <1.8 pmol L(-1) to 34+/-6 pmol L(-1) (n = 6, P < 0.01) while fetal ACTH concentrations remained undetectable (n = 6). Infusion of ACTH1-24 increased cortisol concentrations in maternal plasma from 8.3+/-0.6 mmol L(-1) to 15.8+/-0.8 mmol L(-1) (n = 6, P < 0.001) but had no effect on concentrations of 13,14-dihydro-15-keto-PGF2alpha (P = 0.8). It is concluded that (1) maternal infusion of ACTH1-24 at the dosage used does not induce labour in guinea-pigs, and (2) ACTH1-24 does not cross the placenta.
Schellenberg
J C
JC
Research Centre for Reproductive Medicine, Department of Obstetrics and Gynaecology, University of Auckland, New Zealand. jc.schellenberg@auckland.ac.nz
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003366:Cosyntropin / Q000008:administration & dosage / Q000494:pharmacology*; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000097:blood; D007743:Labor, Obstetric / Q000097:blood / Q000187:drug effects*; D011247:Pregnancy; D013997:Time Factors
D003366:Cosyntropin; C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D000324:Adrenocorticotropic Hormone; D015237:Dinoprost; D006854:Hydrocortisone