The excitatory peptide kisspeptin restores the luteinizing hormone surge and modulates amino acid neurotransmission in the medial preoptic area of middle-aged rats

Endocrinology. 2009 Aug;150(8):3699-708. doi: 10.1210/en.2008-1667. Epub 2009 May 7.

Abstract

Reproductive success depends on a robust and appropriately timed preovulatory LH surge. The LH surge, in turn, requires ovarian steroid modulation of GnRH neuron activation by the neuropeptide kisspeptin and glutamate and gamma-aminobutyric acid (GABA) neurotransmission in the medial preoptic area (mPOA). Middle-aged females exhibit reduced excitation of GnRH neurons and attenuated LH surges under estrogen-positive feedback conditions, in part, due to increased GABA and decreased glutamate neurotransmission in the mPOA. This study tested the hypothesis that altered kisspeptin regulation by ovarian steroids plays a role in age-related LH surge dysfunction. We demonstrate that middle-aged rats exhibiting delayed and attenuated LH surges have reduced levels of Kiss1 mRNA in the anterior hypothalamus under estrogen-positive feedback conditions. Kisspeptin application directly into the mPOA rescues total LH release and the LH surge amplitude in middle-aged rats and increases glutamate and decreases GABA release to levels seen in the mPOA of young females. Moreover, the N-methyl-D-aspartate receptor antagonist MK801 blocks kisspeptin reinstatement of the LH surge. These observations suggest that age-related LH surge dysfunction results, in part, from reduced kisspeptin drive under estrogen-positive feedback conditions and that kisspeptin regulates GnRH/LH release, in part, through modulation of mPOA glutamate and GABA release.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Amino Acids / metabolism*
  • Animals
  • Dizocilpine Maleate / pharmacology
  • Female
  • Glutamic Acid / metabolism
  • Kisspeptins
  • Luteinizing Hormone / metabolism*
  • Neuroprotective Agents / pharmacology
  • Preoptic Area / drug effects
  • Preoptic Area / metabolism*
  • Progesterone / pharmacology
  • Progestins / pharmacology
  • Proteins / genetics
  • Proteins / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Synaptic Transmission / drug effects
  • gamma-Aminobutyric Acid / metabolism

Substances

  • Amino Acids
  • Kiss1 protein, rat
  • Kisspeptins
  • Neuroprotective Agents
  • Progestins
  • Proteins
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • Progesterone
  • gamma-Aminobutyric Acid
  • Dizocilpine Maleate
  • Luteinizing Hormone