Prandial increases of leptin and orexin in the brain modulate spatial learning and memory.
Leptin is well known to be involved in the inhibition of feeding, hermogenesis, reproduction and neuroendocrine functions through its actions on the rodents hypothalamic receptors. Leptin facilitated the presynaptic transmitter release and postsynaptic sensitivity to the transmitters in the hippocampal CA1 neurons. Thus long-term potentiation (LTP) and the phosphorylation of Ca2+/calmodulin protein kinase II (CaMK II) were facilitated in the CA1 neurons. Therefore behavioral performance related to spatial learning and memory was improved by leptin in vivo applications. Orexin-A produced by glucose-sensitive neurons in the lateral hypothalamic area (LHA) and released during food intake facilitates feeding. Orexin-A suppressed LTP and CaMK II phosphorylation without affecting the presynaptic transmitter release. Therefore behavioral performance on learning and memory was impaired. The present studies suggest that leptin and orexin signalings in the brain may have important implications for cognitive function.
Oomura
Yutaka
Y
Kyushu University, Department of Brain Science and Engineering, Graduate School of Life Science and Systems Engineering, Kitakyushu Institute.
Aou
Shuji
S
Fukunaga
Kouji
K
Moriguchi
Sigeki
S
Sasaki
Kazuo
K
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D004435:Eating / Q000502:physiology; D007031:Hypothalamus / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D020738:Leptin / Q000378:metabolism*; D017774:Long-Term Potentiation / Q000502:physiology; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D000068797:Orexins; D051381:Rats; D015398:Signal Transduction / Q000502:physiology
D047908:Intracellular Signaling Peptides and Proteins; D020738:Leptin; D009479:Neuropeptides; D000068797:Orexins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2