Effects of subacute treatment with toluene on cerebrocortical α and β-adrenergic receptors in the rat. Evidence for an increased number and a reduced affinity of β-adrenergic receptors

Subacute treatment with toluene (80-1500 p.p.m.) produces a dose-dependent reduction of affinity and increase in density of the β-adrenergic antagonist [³H]dihydroalprenolol binding sites in the frontoparietal cortex of the male rat, while the binding characteristics of α₁-adrenergic ([³H]WB 4101) and α₂-adrenergic ([³H]p-aminoclonidine) binding sites in the same region is unaffected by this treatment as evaluated in vitro. Therefore, it is suggested that the cortical β-adrenergic receptors are particularly vulnerable to the action of toluene in vivo. It is speculated that as a result cortical α-adrenergic neurotransmission may be altered following exposure to low concentrations of toluene, possibly related to the physico-chemical properties of toluene, leading to changes in membrane fluidity.