Activation of a nitric-oxide-sensitive cAMP pathway with phencyclidine: elevated hippocampal cAMP levels are temporally associated with deficits in prepulse inhibition

• RATIONALE: Schizophrenic patients show deficits in pre-attentive information processing as evidenced, for example, by disrupted prepulse inhibition, a measure of sensorimotor gating. A similar disruption can be observed in animals treated with the psychotomimetic agent, phencyclidine (PCP). However, the mechanism by which PCP alters brain function has not been fully elucidated. Recent studies have demonstrated that certain behavioural and neurochemical effects of PCP in rats and mice are blocked by nitric oxide (NO) synthase inhibition, suggesting an important role for NO in the effects of PCP. OBJECTIVE: The aim of the present study was to investigate the effects of PCP on cAMP production in the ventral hippocampus and the role of NO in these effects using in vivo microdialysis in rats. Furthermore, the effects of PCP on acoustic startle reactivity and prepulse inhibition of acoustic startle were compared with changes in cAMP levels in the ventral hippocampus. RESULTS: Significant increases in cAMP levels were observed in the ventral hippocampus following both local infusion (10(-4) mol/l and 10(-3) mol/l) and systemic administration (2 mg/kg) of PCP. The PCP-induced changes in prepulse inhibition and startle reactivity were associated in magnitude and duration with the increase in cAMP levels in the hippocampus. Furthermore, systemic administration of the NO synthase inhibitor, L: -NAME (10 mg/kg), blocked both the changes in cAMP levels and the behavioural responses induced by PCP. CONCLUSIONS: These findings indicate that the effects of PCP on prepulse inhibition and startle reactivity are associated with an increase in cAMP levels in the ventral hippocampus, and that this change in cAMP response may be linked to the production of NO.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Keyword

Acoustic Stimulation

Animals

Cyclic AMP/*physiology

Enzyme Inhibitors/pharmacology

Excitatory Amino Acid Antagonists/*pharmacology

Hippocampus/*drug effects/*metabolism

Male

Microdialysis

NG-Nitroarginine Methyl Ester/pharmacology

Nerve Tissue Proteins/antagonists & inhibitors

Nitric Oxide/*physiology

Nitric Oxide Synthase/antagonists & inhibitors

Nitric Oxide Synthase Type I

Phencyclidine/*pharmacology

Radioimmunoassay

Rats

Rats

Sprague-Dawley

Startle Reaction/*drug effects

Publication and Content Type

ref (subject category)

art (subject category)