Post-synaptic activity evoked in the rostral ventrolateral medullary neurones by stimulation of the defence areas of hypothalamus and midbrain in the rat.
Neurones in the rostral ventrolateral medulla (RVLM) of the rat were recorded intracellularly (n = 30) and extracellularly (n = 91) in vivo. 91% of them had spontaneous activity with frequencies of 1.1-29.9 Hz. Onset latencies of the excitation induced by the stimulation of the hypothalamic and midbrain defence areas ranged from 1.5 to 44 ms and 2 to 60 ms respectively. There was no statistical difference between two groups. Excitation followed by inhibition or inhibition followed by excitation was observed in these processes. Excitatory post-synaptic potentials (EPSPs) were summated by simultaneous stimulation of both sites and the onset latency was changed with the change of stimulus intensity. It is concluded that projections from the defence areas of hypothalamus and midbrain are relayed to RVLM neurones forming excitatory and inhibitory synapses; one mechanism of the effect summation caused by both sites is via EPSPs.
Gao
K M
KM
Department of physiology, Shanghai Medical University, People's Republic of China.
Li
P
P
D000374:Aggression / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D005110:Extracellular Space / Q000502:physiology; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology*; D008636:Mesencephalon / Q000502:physiology*; D008839:Microelectrodes; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010487:Periaqueductal Gray / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology*
D010656:Phenylephrine