Quantitative autoradiographic studies of the effects of bilateral olfactory bulbectomy in the rat brain: central- and peripheral-type benzodiazepine receptors.
We investigated the discrete regional effects of bilateral olfactory bulbectomy on central- and peripheral-type benzodiazepine receptors in rat brains at weekly intervals until one month after bulb ablation. Persistent increases in [3H]flunitrazepam binding to central benzodiazepine receptors were observed in the cingulum (27%) and in the frontal (15%) and parietal (14%) cortices. Progressive increases in central benzodiazepine receptors, reaching statistical significance four weeks after olfactory bulbectomy, were observed in the ventromedial thalamic nucleus (35%), the lateral hypothalamic region (22%), the basolateral amygdaloid nucleus (23%) and substantia nigra (25%). Persistent major increases (between four- and six-fold) in [3H]PK-11195 [eH]1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide binding to peripheral-type benzodiazepine receptors were observed in all anterior olfactory nuclei. Similarly, throughout the time period studied, [3H]PK-11195 binding densities were increased two- to three-fold in the piriform cortex and lateral olfactory tract. These observations confirm the usefulness of [3H]PK-11195 binding as a marker of neuronal insult in the brain. Moreover, the persistent regional increases in [3H]flunitrazepam binding to central-type benzodiazepine receptors suggest that GABAergic transmission is altered following olfactory bulb ablation.
Beauchemin
V
V
Department of Psychiatry, McGill University, Montréal, Québec, Canada.
Lavoie
N
N
Dennis
T
T
D000818:Animals; D001345:Autoradiography; D001522:Behavior, Animal / Q000187:drug effects; D001923:Brain Chemistry / Q000502:physiology*; D005442:Flumazenil / Q000494:pharmacology; D005445:Flunitrazepam / Q000493:pharmacokinetics; D007546:Isoquinolines / Q000493:pharmacokinetics; D008297:Male; D009830:Olfactory Bulb / Q000502:physiology*; D017933:Peripheral Nervous System / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000502:physiology*
D007546:Isoquinolines; D011963:Receptors, GABA-A; D005442:Flumazenil; D005445:Flunitrazepam; C037850:PK 11195