Effects of microinjections of apomorphine and haloperidol into the inferior colliculus on prepulse inhibition of the acoustic startle reflex in rat.
Prepulse inhibition (PPI) is the reduction in the startle response caused by a low intensity non-startling stimulus (prepulse) which is presented shortly before the startle stimulus and is an operational measure of sensorimotor gating. PPI is impaired in schizophrenia patients and in rats with central dopamine (DA) activation. The inferior colliculus (IC) is a critical part of the auditory pathway mediating acoustic PPI. The activation of the IC by the acoustic prepulse reduces startle magnitude. The aim of this study was to elucidate the role of DA transmission of the IC on the development of acoustic PPI. Bilateral microinjections of apomorphine (9.0 μg/0.5 μL), an agonist of D(2) receptors, into the IC disrupted PPI while microinjections of haloperidol (0.5 μg/0.5 μL), an antagonist of D(2) receptors, into this structure did not alter PPI. These results suggest that dopamine-mediated mechanisms of the IC are involved in the expression of PPI in rodents.
Laboratório de Psicologia Experimental, Departamento de Biociências, Universidade Federal de São Paulo (Unifesp), Av. D. Ana Costa, 95, Santos (SP) 11060-001, Brazil.
Susan
S
Satake
Karen
K
Yamada
Liana Lins
LL
Melo
Regina
R
Barbosa Silva
D000161:Acoustic Stimulation; D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage* / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D006220:Haloperidol / Q000008:administration & dosage* / Q000494:pharmacology*; D007245:Inferior Colliculi / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008845:Microinjections; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000378:metabolism; D013216:Reflex, Startle / Q000187:drug effects* / Q000502:physiology*; D012559:Schizophrenia
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D006220:Haloperidol; D001058:Apomorphine; D004298:Dopamine