intraventricular beta-endorphin , 16 micrograms , caused a marked spinal release of immunoreactive met-enkephalin and to a much lesser extent , of immunoreactive leu-enkephalin while intraventricular morphine , 40 micrograms , did not cause any significant release of immunoreactive enkephalins .
C0014295
met-enkephalin
C0014298
enkephalins