title: Beta-endorphin immunoreactivity levels in CSF after laryngeal chemoreflex activation correlate with apnoea duration in piglets.
abstract: The activation of the laryngeal chemoreflex may be a pathogenic mechanism in apnoea, apparent life threatening events, and SIDS. Infants with apnoea and increased levels of beta-endorphin immunoreactivity in CSF have been successfully treated with naloxone. Beta-endorphin may induce respiratory depression, and naloxone is a beta-endorphin antagonist. We therefore wanted to measure beta-endorphin levels in CSF before and after the chemoreflex induced apnoea. This study includes 13 piglets, 5-10 days of age, treated with and without naloxone. Respiration, blood pressure, and heart rate were monitored. CSF was sampled before and after the laryngeal chemoreflex induced apnoea. We found a shorter duration of apnoea in the piglets which had received naloxone than in those which did not (p = 0.02). The beta-endorphin immunoreactivity levels in CSF increased after apnoea, and the increased levels correlated positively with the duration of the apnoea in the piglets which had not received naloxone (r = 0.94, p = 0.02), but not in those pretreated with naloxone (r = 0.1, p = 0.8). The median amount of beta-endorphin immunoreactivity in CSF after apnoea in the naloxone-treated piglets was not significantly different from that in the non-treated piglets: 615 +/- 589 (n = 7) fmol/ml CSF and 984 +/- 851 (n = 6) fmol/ml CSF, respectively. The beta-endorphin immunoreactivity levels measured before the apnoea were less than 4.3 fmol/ml CSF.
  
  
  CONCLUSIONS
  The laryngeal chemoreflex induced apnoea may possible be partly mediated by beta-endorphin.
authors.affiliation: Department of Paediatric Research, National Hospital, Oslo, Norway.
authors.forename: H
authors.initials: H
authors.lastname: Storm
authors.forename: L
authors.initials: L
authors.lastname: Stoltenberg
authors.forename: O D
authors.initials: OD
authors.lastname: Saugstad
authors.forename: T O
authors.initials: TO
authors.lastname: Rognum
authors.forename: K L
authors.initials: KL
authors.lastname: Reichelt
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001049:Apnea / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced; D005260:Female; D006801:Humans; D007830:Larynx / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology* / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D011863:Radioimmunoassay; D011897:Random Allocation; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D013552:Swine; D013997:Time Factors; D001615:beta-Endorphin / Q000134:cerebrospinal fluid* / Q000187:drug effects
chemical_list: D009292:Narcotic Antagonists; D009270:Naloxone; D001615:beta-Endorphin