Environment-friendly utilization of squid pen with water: Production of β-chitin nanofibers and peptides for lowering blood pressure.

Chitin, an abundant biopolymer on Earth, represents a resource for sustainable functional materials. However, traditional β-chitin production methods involve alkaline treatment at approximately 90 °C for its separation from the protein, thus not suitable as a functional peptide, as it is mixed with an alkaline aqueous solution. This study examined the conversion of squid pen into solid β-chitin and water-soluble peptides using only water at temperatures of 150-250 °C for 30-120 min.

Involvement of dopamine D2 receptor signal transduction in the discriminative stimulus effects of the κ-opioid receptor agonist U-50,488H in rats.

We have reported previously that the inhibition of both dopaminergic and psychotomimetic/hallucinogenic components plays a role in the discriminative stimulus effects of U-50,488H. However, the mechanisms that underlie the discriminative stimulus effects of U-50,488H, and especially the component that plays a significant role, have not yet been clarified. The present study was designed to further investigate the mechanism(s) of the discriminative stimulus effects of the κ-opioid receptor agonist U-50,488H in rats that had been trained to discriminate between 3.

Involvement of serotonin receptor mechanisms in the discriminative stimulus effects of ketamine in rats.

We have demonstrated previously that the ketamine-induced discriminative stimulus effect is likely to reflect the phencyclidine-like psychotomimetic effects. Therefore, the present study was designed to investigate the effects of the antipsychotics and 5-HT2 receptor antagonist on the discriminative stimulus effects of ketamine in rats. While sulpiride did not attenuate the discriminative stimulus effects of ketamine, both clozapine and ketanserin attenuated those of ketamine, suggesting that the discriminative stimulus effects of ketamine are mediated by multiple receptors, especially the 5-HT2 receptor, but not the D2 receptor.