title: Opioid peptides involvement in endotoxin-induced suppression of LH secretion in ovariectomized Holstein heifers.
abstract: Three groups of ovariectomized Holstein heifers were used in this study. Group I heifers (n = 6) were pretreated with saline (SAL), followed 3 h later by three injections of naloxone hydrochloride (NLX) given 1 h apart. In the same sequence, group II heifers (n = 3) received lipopolysaccharide (LPS), followed by the opioid antagonist NLX. Group III heifers (n = 3) received LPS followed by SAL. Concentrations of cortisol and progesterone increased (P < 0.05) following LPS injections in both groups II and III, whereas luteinizing hormone (LH) concentrations were suppressed (P < 0.05). Administration of NLX to heifers pretreated with LPS elicited significant increases (P < 0.05) in LH concentrations, whereas SAL infusion had no effect. These results indicate that the inhibitory actions of opiate mu-delta receptors, and possibly other POMC gene products, were at least partially involved in LPS-induced suppression of the gonadotropic hormone. These results are discussed, including the possibility that feedback suppression by LPS-triggered adrenal gland steroids may have interfered with complete restoration of LH secretion by the opioid antagonist.
authors.affiliation: Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison 53706, USA.
authors.forename: L L
authors.initials: LL
authors.lastname: Kujjo
authors.forename: W T
authors.initials: WT
authors.lastname: Bosu
authors.forename: G I
authors.initials: GI
authors.lastname: Perez
mesh_terms: D000818:Animals; D002417:Cattle; D004731:Endotoxins / Q000008:administration & dosage / Q000633:toxicity*; D004926:Escherichia coli; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006854:Hydrocortisone / Q000097:blood; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000633:toxicity*; D007986:Luteinizing Hormone / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism*; D009270:Naloxone / Q000008:administration & dosage / Q000633:toxicity*; D018847:Opioid Peptides / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D010052:Ovariectomy; D011374:Progesterone / Q000097:blood; D011897:Random Allocation; D017465:Receptors, Opioid, delta / Q000187:drug effects; D017450:Receptors, Opioid, mu / Q000187:drug effects; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage
chemical_list: D004731:Endotoxins; D008070:Lipopolysaccharides; D018847:Opioid Peptides; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D012462:Saline Solution, Hypertonic; D009270:Naloxone; D011374:Progesterone; D007986:Luteinizing Hormone; D006854:Hydrocortisone