Diazepam alters brain-stimulation reward thresholds in seizure-prone sites.
Studies of the effect of diazepam and related compounds on the rewarding properties of brain stimulation as measured by response rates have not yielded clear results, with self-stimulation performance reported to be potentiated, diminished, or unchanged following drug administration. In this study, the effect of two doses of diazepam (2.5 and 5.0 mg/kg) and its vehicle on self-stimulation thresholds was examined in eight rats with electrode placements scattered along a 4 mm length of the medial forebrain bundle. Stimulation of the lateral preoptic area and the anterior and mid-lateral hypothalamus produced overt seizures. Rate-period curves were generated for a wide range of currents and the resulting period-current trade-off functions were compared across doses. In seizure-prone sites upward shifts in period threshold were observed after 2.5 mg/kg of diazepam with little additional increases incurred by the 5.0 mg/kg dose. The majority of non-seizure sites showed no effects of diazepam upon period threshold. The results suggest that diazepam alters brain-stimulation reward thresholds by suppressing competing seizure activity.
Harris
T
T
School of Psychology, University of Ottawa, Ontario, Canada.
Bielajew
C
C
D000818:Animals; D001931:Brain Mapping; D003975:Diazepam / Q000494:pharmacology*; D007026:Hypothalamic Area, Lateral / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D008474:Medial Forebrain Bundle / Q000187:drug effects / Q000503:physiopathology; D009042:Motivation; D011301:Preoptic Area / Q000187:drug effects / Q000503:physiopathology; D051381:Rats; D012201:Reward; D012640:Seizures / Q000503:physiopathology*; D012653:Self Stimulation / Q000187:drug effects* / Q000502:physiology; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology; D013681:Tegmentum Mesencephali / Q000187:drug effects / Q000503:physiopathology
D003975:Diazepam