Direct and long-lasting effects elicited by repeated drug administration on 50-kHz ultrasonic vocalizations are regulated differently: Implications for the study of the affective properties of drugs of abuse

Several studies suggest that 50-kHz ultrasonic vocalizations (USVs) may indicate a positive affective state in rats, and these vocalizations are increasingly being used to investigate the properties of psychoactive drugs. Previous studies, however, have focused on dopaminergic psychostimulants and morphine, whereas little is known about how other drugs modulate 50-kHz USVs. To further elucidate the neuropharmacology of 50-kHz USVs, the present study characterized the direct and long-lasting effects of different drugs of abuse, by measuring the number of 50-kHz USVs and their 'trill' subtype emitted by adult male rats. Rats received repeated administrations of amphetamine (2 mg/kg, i.p.), 3,4-methylenedioxymethamphetamine (MDMA, 7.5 mg/kg, i.p.), morphine (7.5 mg/kg, s.c.), or nicotine (0.4 mg/kg, s.c.), on either consecutive or alternate days (five administrations in total) in a novel environment. Seven days later, rats were re-exposed to the drug-paired environment, subjected to USVs recording, and then challenged with the same drug. Finally, 7 d after the challenge, rats were repeatedly exposed to the drug-paired environment and vocalizations were measured. Amphetamine was the only drug to stimulate 50-kHz USVs and 'trill' subtype emission during administration and challenge. Conversely, all rats emitted 50-kHz USVs when re-exposed to the test cage, and this effect was most marked in morphine-treated rats, and less evident in nicotine-treated rats. This study demonstrates that the direct and long-lasting effects of drugs on 50-kHz USVs are regulated differently, providing a better understanding of the usefulness of these vocalizations in the study of psychoactive drugs

Synthesis of 6-amino and 6-ethoxy-2(1H)-pyridone derivatives.

An efficient route allowing the synthesis of 6-amino and 6-ethoxy-2(1H)-pyridone derivatives by reaction of ethyl cyanoacetimidate, ethyl ethoxycarbonylacetimidate and related acetamidines with diethyl ethoxymeth-ylenemalonate (EMME) is reported. The formation of dienamino derivatives as intermediates and their heterocyclization to the 2(1H)-pyridone derivatives is described

Synthesis and antimicrobial activity of novel arylidenisothiosemicarbazones

Arylidenimidazoles bearing a thioethereal function in the position 2 of the imidazole ring show good antimicrobial activity. We now report on the synthesis and the biological properties of some novel arylidenisothiosemicarbazones, structurally related to the arylideneiminoimidazoles of which they can be considered the linear precursors. Particular attention has been put on the influence of structural modifications on the biological activity

On the acylation of 1,3-benzoxathiole systems.

The acylation on 1,3-benzoxathiole systems, as well as the effect of the stoichiometry of the catalyst on the yields of ketones and of breaking products of the OCS bonds is here described