Effects of stresscopin on rat hypothalamic paraventricular nucleus neurons in vitro.
The effects of stresscopin (SCP) on rat paraventricular nucleus (PVN) neurons were examined using whole-cell patch-clamp recordings and single-cell reverse-transcription multiplex polymerase chain reaction (SC-RT-mPCR) techniques. Under current-clamp conditions, bath application of SCP (100 nM) induced inhibition in 35.2% (37/105) of putative magnocellular neurons and 24.7% (20/81) of putative parvocellular neurons, and excitation in 5.7% (6/105) of putative magnocellular neurons and 18.5% (15/81) of putative parvocellular neurons. SCP-induced inhibition persisted in the presence of a mixture of TTX, a voltage-gated Na+ channel blocker, CNQX, an AMPA/kainate receptor antagonist and bicuculline, a GABA(A) receptor antagonist, whereas SCP-induced excitation of PVN neurons was reversed by the mixture. The SCP-induced inhibition of PVN neurons was abolished by bath application of antisauvagine-30, a selective CRF receptor 2 (CRF-R2) antagonist. Under voltage-clamp conditions, SCP evoked outward currents at the holding potential (-60 mV), which reversed near the potassium equilibrium potential. The SCP-evoked membrane currents were completely blocked by bath application of tertiapin-Q, a selective blocker of G protein-activated inwardly rectifying potassium (GIRK) channels. SC-RT-mPCR analysis indicated that all the SCP-sensitive PVN neurons (57 SCP-inhibited neurons, 21 SCP-excited neurons) expressed CRF-R1 and CRF-R2 mRNAs. Among SCP-hyperpolarized PVN neurons, oxytocin (OT) mRNA was detected in 91.8% of putative magnocellular neurons and 45.0% of putative parvocellular neurons. OT mRNA was also detected in 26.6% of SCP-depolarized parvocellular neurons, but not in SCP-depolarized magnocellular neurons. These results indicate that SCP inhibits a subpopulation of PVN neurons, especially OTergic magnocellular neurons, by enhancing the activity of GIRK channels via CRF-R2.
Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, People's Republic of China.
Chun-Ping
CP
Chu
Wen-Zhe
WZ
Jin
Yan-Hua
YH
Bing
Qing-Hua
QH
Jin
Hiroshi
H
Kannan
De-Lai
DL
Qiu
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D010121:Oxytocin / Q000235:genetics; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics; D054832:Urocortins / Q000494:pharmacology*; D000099052:CRF Receptor, Type 1
C101531:CRF receptor type 2; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; C426704:UCN3 protein, human; D054832:Urocortins; D010121:Oxytocin; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone