Single-unit activity of paraventricular nucleus neurons in response to intero- and exteroceptive stressors in conscious, freely moving rats.
Extracellular recordings of 114 neurons in the hypothalamic paraventricular nucleus (PVN) of conscious, freely moving male rats were performed using a movable electrode system. Single-unit activities were examined for their spontaneous firing patterns and responses to intero- and exteroceptive stressors, including disturbance in arterial blood pressure, water deprivation, air-jet stimulation, and systemic administration of cholecystokinin-8 (CCK). PVN neurons were assigned to one of two groups on the basis of their spontaneous firing patterns: phasic (n=29) and non-phasic (n=85). Intravenous (i.v.) administration of phenylephrine (8 microg/kg) resulted in the inhibition of a greater percentage of phasic-type (88.9%; 24/27) than non-phasic-type neurons (14.9%; 11/74). Most phasic-type neurons showed excitation in response to i.v. administration of sodium nitroprusside (20 microg/kg, 66.7%; 18/27) and water deprivation (15 h, 77.8%; 7/9) when compared to non-phasic-type neurons. Conversely, a greater number of non-phasic-type neurons showed excitation in response to air-jet stimulation (5 l/min, 10 s, 29.0%; 20/69) and to i.v. administration of CCK (5 microg/kg, 24.5%; 11/45) when compared to phasic-type neurons. However, most non-phasic-type neurons that demonstrated excitation in response to i.v. administration of CCK (88.9%; 8/9) did not respond to air-jet stimulation. The present study indicated that phasically firing neurons recorded from the PVN in conscious, freely moving rats are putative vasopressin-secreting neurons on the basis of their responses to intero- and exteroceptive stressors. These data contribute to our understanding of local neural mechanisms within the PVN that are responsible for stress responses in conscious rats.
Watanabe
Shoichi
S
Department of First Physiology, Miyazaki Medical College, 5200 Kihara, Kiyotake-cho, Miyazaki-gun, Miyazaki 889-1692, Japan.
Kunitake
Takato
T
Kato
Kazuo
K
Chu
Chun-Ping
CP
Nakao
Hiroyuki
H
Qiu
De-Lai
DL
Kannan
Hiroshi
H
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D017776:Autonomic Pathways / Q000166:cytology / Q000502:physiology*; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003243:Consciousness / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000166:cytology / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009068:Movement / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D012844:Sincalide / Q000494:pharmacology; D013312:Stress, Physiological / Q000503:physiopathology*; D013315:Stress, Psychological / Q000503:physiopathology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014868:Water Deprivation / Q000502:physiology
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D012844:Sincalide