Differential regional development of tolerance to increase in dopamine turnover upon repeated neuroleptic administration

Repeated treatment with haloperidol and sulpiride induced tolerance to the increases in homovanillic and dihydroxyphenyl acetic acids in the striatum, nucleus accumbens, tuberculum olfactorium and frontal cortex of the rat, and results were found in the frontal cortex by measuring dopamine utilization.

Abstract

Chirality in molecular opto-electronics is limited sofar to the use of optically active liquid crystals and a number of optical phenomena are related to the helical macroscopic structure obtained by using one enantiomer, only. In this paper, the use of chirality in nonlinear optics and optical switching is demonstrated. The additional options offered by the combination of circularly polarized light and chiral molecules gives rise to the observation of Second Harmonic Generation from centrosymmetric crystals of a racemic mixture. This phenomenon is due to the existence of optical activity in the hyperpolarizability. Chiroptical switching is observed in inherently dissymmetric molecules, that can undergo a photochemical isomerization of a strongly dextrorotatory isomer into a strongly laevorotatory isomer. Using circular dichroism the switching between these two pseudo-enantiomers can be monitored accurately.