Effects of suramin on neuroendocrine and behavioural responses to conditioned fear stimuli.
Conditioned fear stimuli suppress motor activity. The fear stimuli suppress vasopressin and facilitate oxytocin and prolactin release. These fear responses are impaired by selective destruction of noradrenergic neurones. Adenosine 5'-triphosphate is co-released from noradrenergic nerve terminals with noradrenaline. Thus the possibility arises that the behavioural and neuroendocrine responses may be mediated by purinergic rather than noradrenergic synapses. We examined whether suramin, an inhibitor of P2 and NMDA receptors, blocks conditioned fear responses. Suramin injected i.c.v. 30 min before testing stimuli impaired conditioned fear responses. The role of purinergic P2 receptors in expression of the behavioural and neuroendocrine responses to conditioned fear stimuli is discussed.
Zou
C J
CJ
Department of Physiology, Jichi Medical School, Tochigi-ken, Japan.
Onaka
T O
TO
Yagi
K
K
D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D004597:Electroshock; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005239:Fear / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D009490:Neurosecretory Systems / Q000187:drug effects*; D010121:Oxytocin / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D013498:Suramin / Q000494:pharmacology*; D014667:Vasopressins / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D014667:Vasopressins; D010121:Oxytocin; D013498:Suramin; D011388:Prolactin