title: Patterns of release of oxytocin, prolactin, insulin and LH in lactating sows, studied using continuous blood collection technique.
abstract: To describe the patterns of release of oxytocin, prolactin, insulin and LH in relation to suckling and to investigate relationships between them, blood was collected continuously from four sows at a rate of 1 ml per min for 12 h (0900-2100 h) on day 10 (D10) and day 20 (D20) of lactation. The 12-h period was divided into four smaller periods: P1 (0900-1200 h), P2 (1200-1500 h), P3 (1500-1800 h) and P4 (1800-2100 h). The number of nursings occurring during a 12-h period tended to decrease between D10 (17.3 +/- 0.3) and D20 (16.0 +/- 0.3). About 40-50% of all sucklings induced a significant rise in plasma oxytocin, while prolactin gradually increased following each suckling. Decrease in the levels of oxytocin (14.1 +/- 0.4 vs 7.1 +/- 0.4 pmol/l, P < 0.001), prolactin (12.9 +/- 0.3 vs 7.9 +/- 0.1 micrograms/l, P < 0.001) and insulin (24.8 +/- 1.7 vs 14.4 +/- 1.7 mU/l, P < 0.001) were observed between D10 and D20. Average and basal levels of LH and the number of LH pulses increased (P < 0.01) between D10 and D20. A negative correlation between number of sucklings and number of LH pulses was demonstrated on D20 (r = -0.59, P = 0.07). There was a positive correlation between levels of LH and oxytocin on D10 (r = 0.54, P = 0.001) and between prolactin and insulin levels on D20 (r = 0.34, P = 0.05).
authors.affiliation: Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala.
authors.forename: T
authors.initials: T
authors.lastname: Rojkittikhun
authors.forename: S
authors.initials: S
authors.lastname: Einarsson
authors.forename: K
authors.initials: K
authors.lastname: Uvnäs-Moberg
authors.forename: N
authors.initials: N
authors.lastname: Lundeheim
authors.forename: A
authors.initials: A
authors.lastname: Madej
mesh_terms: D000818:Animals; D001800:Blood Specimen Collection / Q000662:veterinary; D005260:Female; D006728:Hormones / Q000097:blood*; D007328:Insulin / Q000097:blood; D007774:Lactation / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D010121:Oxytocin / Q000097:blood; D011388:Prolactin / Q000097:blood; D013552:Swine / Q000097:blood*
chemical_list: D006728:Hormones; D007328:Insulin; D010121:Oxytocin; D011388:Prolactin; D007986:Luteinizing Hormone