Related Experiment Videos
Orexin A activates leptin-responsive neurons in the arcuate nucleus
M Rauch1, T Riediger, H A Schmid
1Max-Planck-Institut für Physiologische und Klinische Forschung, Bad Nauheim, Germany.
Pflugers Archiv : European Journal of Physiology
|September 28, 2000
Summary
Orexins, brain peptides that increase appetite, directly excite neurons in the hypothalamus. Leptin, a hormone that reduces appetite, affects these orexin-sensitive neurons, suggesting a key interaction point for appetite regulation.
Area of Science:
- Neuroscience
- Neuroendocrinology
- Appetite Regulation
Background:
- Orexins (hypocretins) are hypothalamic neuropeptides stimulating food intake.
- Leptin, a hormone from adipocytes, is known to reduce food intake, primarily via hypothalamic arcuate nucleus (ARC) neurons.
Purpose of the Study:
- To investigate the electrophysiological effects of orexin A on rat arcuate nucleus neurons.
- To determine how leptin influences orexin-sensitive neurons within the arcuate nucleus.
Main Methods:
- Electrophysiological recordings were performed on rat arcuate nucleus neurons in an in vitro slice preparation.
- The effects of orexin A application on neuronal activity were assessed.
- The impact of leptin on orexin-sensitive neurons was subsequently examined.
Main Results:
- Orexin A demonstrated a potent excitatory effect, activating 85% of investigated arcuate nucleus neurons via direct postsynaptic mechanisms.
- Leptin exhibited differential effects on orexin-sensitive neurons, inhibiting 10 out of 22 and exciting only 3.
Conclusions:
- Orexin A directly excites a majority of arcuate nucleus neurons.
- Leptin modulates the activity of orexin-sensitive neurons in the arcuate nucleus.
- These findings provide the first evidence for a direct interaction between orexin and leptin signaling pathways in the hypothalamus.