Seasonal and dose-dependent effects of intracerebroventricular leptin on lh secretion and appetite in sheep

D W Miller, P A Findlay, M A Morrison, N Raver, C L Adam

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

The role of leptin in neuroendocrine appetite and reproductive regulation remains to be fully resolved. A series of three experiments was conducted using adequately nourished oestradiol-implanted castrated male sheep. In a cross-over design (n=6), responses to a single i.c.v. (third ventricle) injection of leptin (0.5, 1.0 and 1.5 mg ovine leptin (oLEP) and 1.0 mg murine leptin (mLEP)), N-methyl-D-aspartate (NMDA, 20 micro g) or 0.9% saline (control) were measured in terms of LH secretion (4 h post-injection compared with 4 h pre-injection) and appetite (during 2 h post-injection) in autumn (Experiment 1). NMDA and 1.0 mg oLEP treatments were repeated in the same sheep in the following spring (Experiment 2). With an additional 12 sheep (n=18 in cross-over design), responses to low-dose 'physiological' i.c.v. infusion of leptin (8 ng/h for 12 h daily for 4 days), insulin (0.7 ng/h) and artificial cerebrospinal fluid were measured in the next spring (Experiment 3). LH was studied over 8 h and appetite over 1 h on days 1 and 4 of infusion. In Experiment 1 (autumn), oLEP overall increased LH pulse frequency by up to 110% (P
Original languageEnglish
Pages (from-to)395-404
Number of pages10
JournalJournal of Endocrinology
Volume175
Issue number2
Publication statusPublished - 2002

Keywords

  • Animals
  • Appetite
  • Dose-Response Relationship, Drug
  • Injections, Intraventricular
  • Insulin
  • Leptin
  • Luteinizing Hormone
  • Male
  • N-Methylaspartate
  • Orchiectomy
  • Radioimmunoassay
  • Seasons
  • Sheep

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