Kappa Opioid Receptor Activation Disrupts Prepulse Inhibition of the Acoustic Startle in Rats

Linking Stress and Schizophrenia: A Focus on Prepulse Inhibition

“…The author interpreted these results as a general decrease in sensory sensitivity, which extends beyond the noxious stimulus (i.e., cold water). The finding supports a possible role for opiates in the PPI-disruptive effect of analgesia, in that opioid receptor agonists, which produce perceptual distortions in animals and humans, disrupt PPI in a dose-dependent fashion (Bortolato et al, 2005). However, another nociceptive stressor, i.e., repeated inescapable foot-shocks, slightly increases PPI (Pijlman et al, 2003), or has no effect (Bijlsma et al, 2010;Bakshi et al, 2011).…”

Neuropharmacology of the Naturally Occurring κ-Opioid Hallucinogen Salvinorin A

“…A growing body of evidence (for a comprehensive review, see Schwarzer, 2009) suggests that the perceptual disturbances associated with schizophrenia may be mediated in part by dysregulation of the release of the endogenous KOP agonist dynorphin (Heikkilä et al, 1990;Hurd, 2002;Bortolato and Solbrig, 2007). In studies monitoring prepulse inhibition in Sprague-Dawley rats as a measure of sensorimotor gating in patients with schizophrenia, KOP agonists such as U50,488 have been found to produce dose-dependent reduction in prepulse inhibition that is reversed upon administration of the KOP receptor antagonist norBNI (Bortolato et al, 2005). A second group (Tejeda et al, 2010) failed to confirm these findings, however, indicating that more studies are required to understand the utility of KOP receptor activity in psychotic disorders.…”

Antipsychotic-Like Properties of 5-α-Reductase Inhibitors

“…Acoustic startle reflex and PPI were studied as described (Bortolato et al, 2005). Briefly, rats were placed in a startle reflex apparatus (Med Associates, St Albans, VT, USA) for a 5-min acclimatization period with a 70 dB background noise, which continued for the remainder of the session.…”