The median preoptic nucleus participates in the control of paraventricular vasopressin neurons by the subfornical organ in the rat.
Extracellular single-unit activity was recorded from phasically firing neurohypophyseal neurons (n = 41) in the hypothalamic paraventricular nucleus (PVN) of urethane-anesthetized male rats. Electrical stimulation of the subfornical organ (SFO) produced orthodromic long-duration (n = 18) or short-duration (n = 10) excitation or inhibition (n = 8) of the activity of PVN neurons. The long-duration excitatory response of about half (n = 7) the neurons (n = 15) tested was reversibly abolished by microinjection of the local anesthetic lidocaine into the median preoptic nucleus (MnPO), whereas neither the short-duration excitatory (n = 7) nor inhibitory (n = 6) responses were affected. These results suggest that the SFO efferents through the MnPO to the PVN may transmit the neuromodulatory signals which evoke long-duration increases in the excitability of putative vasopressin (VP)-secreting neurons in the PVN.
Tanaka
J
J
Department of Physiology, Kochi Medical School, Japan.
Saito
H
H
Seto
K
K
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004558:Electric Stimulation; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009490:Neurosecretory Systems / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism / Q000502:physiology*; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013356:Subfornical Organ / Q000502:physiology*; D014667:Vasopressins / Q000502:physiology*
D014667:Vasopressins; D008012:Lidocaine