Prolactin and growth hormone clearance in neonatal boars

Abstract

The pharmacokinetics of prolactin (PRL) and growth hormone (GH) are not known in neonatal pigs. In this study, six boars, ages 13 and 26 d, were used to determine metabolic clearance rate (MCR), half-life (t1/2), and volume of distribution (Vd) of immunoreactive porcine PRL (ipPRL) and immunoreactive porcine GH (ipGH). Blood samples were collected through indwelling jugular catheters at 0, 1, 2.5, 5, 10, 15, 30, 45, and 60 min after a 20 ng/g of BW (per hormone) cocktail of porcine PRL and GH. Analysis of the ipPRL disappearance curves indicated an apparent MCR of 13.79 +/- 2.45 and 23.79 +/- 4.10 mL/min for boars at 13 and 26 d of age, respectively (P = .0008). The t1/2 of ipPRL did not differ between ages (P = .9201). The apparent MCR of ipGH at 13 and 26 d were 10.60 +/- 2.09 and 27.30 +/- 4.55 mL/min, respectively, and this difference was still evident after adjustment for BW (P = .0465). The ipGH t1/2 decreased with age (P = .0232), 21.32 +/- 2.55 vs 13.57 +/- 3.35 min for 13 and 26 d, respectively. The apparent distribution volume for ipPRL was higher than that for ipGH at both ages (P = .0021). Within each age, the apparent MCR of ipGH and ipPRL did not differ significantly. These data represent the first clearance measures reported for ipPRL and ipGH in neonatal pigs and indicate that under the conditions of this study the apparent MCR of ipPRL and ipGH are similar but change significantly during early development.

Growth hormone: a newly identified developmental organizer

“…In spite of the administration of exogenous GH during the first 12 days of life, circulating levels of the hormone were the same as controls. This seemingly unexpected finding could be explained by the presence of a functional hypothalamic-pituitary GH feedback loop in which the administered GH suppressed secretion of endogenous hormone (Oliver et al, 1982; Wehrenberg and Giustina, 1992) and/or by the fact that blood collections occurred 12h after the last GH injection at which time the exogenous hormone could have cleared from the circulation (Brownborg et al, 1993). Concomitant administration of MSG and GH resulted in essentially normal-like levels of circulating hormone until the GH was withdrawn, and like the MSG treatment alone, plasma GH concentrations were now undetectable in the pups.…”

Sodium oxybate increases prolactin secretion in narcolepsy patients and healthy controls

“…For PRL, the fast half-life was represented as 3.5 min constituting 37% of the decay amplitude and the slow half-life was represented as an unknown variable between 20 and 50 min (33,34). All candidate pulse-time sets were deconvolved.…”