TY - JOUR
T1 - Opioid and Antiopioid Actions of Tyr-MIF-1, Tyr-W-MIF-1 and Hemorphin-4 on Rat Locus Coeruleus Neurons
T2 - Intracellular Recording in vitro
AU - Yang, Yea Ru
AU - Chiu, Tsai Hsien
PY - 1997/9/1
Y1 - 1997/9/1
N2 - Intracellular recording was used to study the effects of naturally occurring opioid tetrapeptides, including Tyr-Pro-Leu-Gly-NH 2 (Tyr-MIF-1), Tyr-Pro-Trp-Gly-NH 2 (Tyr-W-MIF-1), and Tyr-Pro-Trp-Thr-OH (hemorphin-4), on neurons of the locus coeruleus (LC) in the rat, in a totally submerged brain slice preparation. These tetrapeptides which, like other opioids, caused inhibitory effects on all LC neurons tested. Tyr-MIF-1 (10-100 μM), Tyr-W-MIF-1 (1-10 μM) and hemorphin-4 (1-30 μM) caused dose-related inhibition of the spontaneous firing. The IC 50 were 37.5, 3.8 and 6.7 μM for Tyr-MIF-1, Tyr-W-MIF-1 and hemorphin-4, respectively. In addition, these tetrapeptides were tested for their blocking effects on the Tyr-D-Arg-Phe-sarcosine-OH (TAPS)-induced inhibitory actions. The results showed that Tyr-MIF-1, Tyr-W-MIF-1 and hemorphin-4 significantly decreased the actions of lower concentration of TAPS (30 nM), but did not decrease the actions of higher concentration of TAPS (100 nM). It is concluded that the blood-derived peptide hemorphin-4 and the endogenous peptides Tyr-W-MIF-1 and Tyr-MIF-1 possess opioid and antiopioid actions in the LC neurons.
AB - Intracellular recording was used to study the effects of naturally occurring opioid tetrapeptides, including Tyr-Pro-Leu-Gly-NH 2 (Tyr-MIF-1), Tyr-Pro-Trp-Gly-NH 2 (Tyr-W-MIF-1), and Tyr-Pro-Trp-Thr-OH (hemorphin-4), on neurons of the locus coeruleus (LC) in the rat, in a totally submerged brain slice preparation. These tetrapeptides which, like other opioids, caused inhibitory effects on all LC neurons tested. Tyr-MIF-1 (10-100 μM), Tyr-W-MIF-1 (1-10 μM) and hemorphin-4 (1-30 μM) caused dose-related inhibition of the spontaneous firing. The IC 50 were 37.5, 3.8 and 6.7 μM for Tyr-MIF-1, Tyr-W-MIF-1 and hemorphin-4, respectively. In addition, these tetrapeptides were tested for their blocking effects on the Tyr-D-Arg-Phe-sarcosine-OH (TAPS)-induced inhibitory actions. The results showed that Tyr-MIF-1, Tyr-W-MIF-1 and hemorphin-4 significantly decreased the actions of lower concentration of TAPS (30 nM), but did not decrease the actions of higher concentration of TAPS (100 nM). It is concluded that the blood-derived peptide hemorphin-4 and the endogenous peptides Tyr-W-MIF-1 and Tyr-MIF-1 possess opioid and antiopioid actions in the LC neurons.
KW - Hemorphin-4
KW - Intracellular recording
KW - Locus coeruleus
KW - Tyr-MIF-1
KW - Tyr-W-MIF-1
UR - http://www.scopus.com/inward/record.url?scp=0031591798&partnerID=8YFLogxK
M3 - Article
C2 - 9434888
AN - SCOPUS:0031591798
SN - 0304-4920
VL - 40
SP - 131
EP - 135
JO - Chinese Journal of Physiology
JF - Chinese Journal of Physiology
IS - 3
ER -