This paper reports that vasopressin is emetogenic in the house musk shrew Suncus murinus. Either intravenous or intracerebroventricular administration of vasopressin caused vomiting within a few minutes. The ED50 of intravenous vasopressin was as high as 4.67 μg/kg, whereas intracerebroventricularly injected vasopressin was effective at a low dose of 20 ng/brain. The emetogenic target of vasopressin may therefore be present in the central nervous system. We propose the Suncus as a useful animal for investigation of vasopressin-mediated emesis, including motion sickness.
Oseltamivir, a widely used anti-influenza drug, inhibits virus neuraminidase. A mammalian homologue of this enzyme is expressed in the brain, yet the effect of oseltamivir on central neurons is largely unknown. Patch-clamp recordings ex vivo revealed that oseltamivir enhanced spike synchronization between hippocampal CA3 pyramidal cells. Time-lapse multineuron calcium imaging revealed that oseltamivir and its active metabolite evoked synchronized population bursts that recruited virtually all neurons in the network. This unique, so-far-unknown, event was attenuated by muscarinic receptor antagonist. Thus, oseltamivir is a useful tool for investigating a new aspect of neural circuit operation.