Hypothalamic and zona incerta neurons in sheep, initially only responding to the sight of food, also respond to the sight of water after intracerebroventricular injection of hypertonic saline or angiotensin II.
Extracellular single-unit recordings were made from neurons in the lateral hypothalamus (LH) or zona incerta (ZI) of conscious sheep. A small population of neurons (12/83) were found which responded with increased firing rate when the animal looked at food but did not respond when the sheep looked at water. The effects of rapidly inducing intense thirst by the intracerebroventricular (i.c.v.) injection of hypertonic (0.85 M) saline or 200 ng of angiotensin II, or a mixture of the two dipsogenic stimuli, on the response of neurons initially responding only to the sight of food were investigated. Following i.c.v. injection of the dipsogenic stimuli the neurons began to respond strongly to the sight of water. The results demonstrated that changing the animal's motivational state alters the response of some neurons in the LH and ZI and suggests that the neuronal response is influenced by the animal's dominant need at the time of testing.
Mungarndee
Suriyaphun S
SS
Neuro-Behavioural Biology Center, Institute of Science and Technology for Research and Development, Mahidol University at Salaya, Nakorn Pathom 73170, Thailand. stssc@mahidol.ac.th
Baldwin
Basil A
BA
Chindadoungratana
Chittin
C
Kotchabhakdi
Naiphinich
N
D000804:Angiotensin II / Q000008:administration & dosage*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D005260:Female; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D007276:Injections, Intraventricular; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D010775:Photic Stimulation; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage*; D012756:Sheep; D020530:Subthalamus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
D012462:Saline Solution, Hypertonic; D000804:Angiotensin II