A new oxytocin-saporin cytotoxin for lesioning oxytocin-receptive neurons in the rat hindbrain.
Evidence suggests that release of oxytocin in the nucleus tractus solitarius (NTS) of the hindbrain from descending projections that originate in the paraventricular nucleus can inhibit food intake by amplifying the satiety response to cholecystokinin (CCK). To further evaluate this mechanism in rats, we used a novel cytotoxin, saporin conjugated to oxytocin (OXY-SAP), a compound designed to destroy cells that express oxytocin receptors (OXYr). OXY-SAP was injected directly into the NTS to lesion neurons that express OXYr and that are implicated in potentiating CCK's satiety effects. The control consisted of injection of saporin conjugated to a nonsense peptide. We found that OXY-SAP was cytotoxic to human uterine smooth muscle cells in vitro, demonstrating that OXY-SAP can lesion cells that express OXYr. Using laser capture microdissection and real-time quantitative PCR, we demonstrated that OXYr mRNA levels were reduced in the NTS after OXY-SAP administration. Moreover, we found that OXY-SAP attenuated the efficacy of CCK-8 to reduce food intake and blocked the actions of an OXYr antagonist to stimulate food intake. The findings suggest that OXY-SAP is an effective neurotoxin for in vivo elimination of cells that express OXYr and is potentially useful for studies to analyze central nervous system mechanisms that involve the action of oxytocin on food intake and other physiological processes.
Baskin
Denis G
DG
Office of Research and Development Medical Research Service, Veterans Affairs Puget Sound Health Care System, Department of Veterans Affairs Medical Center, Seattle, Washington 98108, USA.
Kim
Francis
F
Gelling
Richard W
RW
Russell
Brian J
BJ
Schwartz
Michael W
MW
Morton
Gregory J
GJ
Simhan
Hyagriv N
HN
Moralejo
Daniel H
DH
Blevins
James E
JE
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003603:Cytotoxins / Q000737:chemistry / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D053583:Interleukin-1beta / Q000235:genetics; D008297:Male; D009215:Myometrium / Q000166:cytology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010121:Oxytocin / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012249:Rhombencephalon / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D054789:Ribosome Inactivating Proteins, Type 1 / Q000737:chemistry / Q000494:pharmacology*; D000076985:Saporins; D012844:Sincalide / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D003603:Cytotoxins; D053583:Interleukin-1beta; D018045:Receptors, Oxytocin; D054789:Ribosome Inactivating Proteins, Type 1; D014409:Tumor Necrosis Factor-alpha; D010121:Oxytocin; D000076985:Saporins; D012844:Sincalide