Estrogen decreases the responsiveness of subfornical organ neurons projecting to the hypothalamic paraventricular nucleus to angiotensin II in female rats.
Extracellular single-unit activity was recorded from subfornical organ (SFO) neurons antidromically identified as projecting to the hypothalamic paraventricular nucleus (PVN) in urethane-anesthetized ovariectomized female rats that were treated with either propylene glycol (PG) vehicle or estradiol benzoate (EB). No significant differences were observed between the PG- and EB-treated rats in the latency, conduction velocity, or threshold of antidromic activation. The mean spontaneous firing rate was significantly lower and the refractory period was significantly longer in the EB-treated rats. In the identified units that were activated by angiotensin II (ANG II) applied iontophoretically, the amount of excitatory response to intracarotid administration of ANG II was much greater in the PG-treated than in the EB-treated rats. These results suggest that estrogen may decrease the responsiveness of SFO neurons projecting to the PVN to circulating ANG II.
Tanaka
J
J
Department of Human Development, Naruto University of Education, Takashima, Naruto-cho, Naruto, 772-8502, Tokushima, Japan. tanakaj@naruto-u.ac.jp
Miyakubo
H
H
Okumura
T
T
Sakamaki
K
K
Hayashi
Y
Y
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D004347:Drug Interactions / Q000502:physiology*; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013356:Subfornical Organ / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology
D004967:Estrogens; D000804:Angiotensin II