Use of antisense oligodeoxynucleotides to study the physiological functions of neuropeptide Y

Stimulation of appetite and regulation of reproductive hormone secretion are two well-known physiological effects of neuropeptide Y (NPY) that have been affirmed using the antisense oligodeoxynucleotide (ODN) approach. Because NPY-producing neurons are concentrated in a narrow band in the arcuate nucleus of the hypothalamus, ODNs injected intracerebroventricularly have easy access to them. In an early study intracerebroventricular administration of an unmodified phosphodiester ODN sequence blocked de novo NPY synthesis and prevented the preovulatory surge release of gonadotropins. Microinjection directly into the arcuate nucleus attenuated NPY-related feeding, however, to unequivocally block the effects of NPY on feeding behavior, long-term inhibition of NPY gene expression was required. This was achieved using phosphorothioated ODNs that, unlike the phosphodiester sequences, are not subject to rapid degradation in vivo. Central administration of these modified ODNs elicited toxic effects that were circumvented by end-capping the sequences. Similar end-capped phosphorothioated ODN sequences have been used to identify the NPY receptor subtypes involved in stimulation of feeding.