SMITHSONIAN SCI  NCE INFORMATION EXCHANGE
       Do NOf use this space)      U.S. DEPARTldENT OF       PROJECT NU:rlBER
PROJECT NUMBER                  HEALTH EDUCATION AND WELFARE
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                                 NOTIGE.GF
                          lNTAMlU?AL RESEARCH PROJECT   201 HL 00002-03 LBG

PER IO0 COVERED

I                      I

July 1, 1975 through June 30, 1976
TITLE OF PROJECT (80 characters or less)

I Morphine Receptors as Regulators of Adenylate Cyclase

NAMES, LABORATORY AN0 INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT

PI:    Marshall Nirenberg     Chief, Lab. of Biochemical
                           Genetics                   LBG NHLI
OTHHR:  Arthur Lampert         Staff Fellow                 LBG NHLI
      Werner Klee           Research Chemist             LGCB NIMH

COOPERATING UNITS (if any)

Laboratory of General and Comparative Biochemistry, NIMH

LAB/BRANCH
Laboratory of Biochemical Genetics

,Section on Molecular Biology
INSTITUTE AND LOCATION
NHLI, NIH, Bethesda, Maryland 20014
TOTAL MANYEARS:            PROFESSIONAL:           OTHER:
     1.2               1.2
SUMMARY OF WORK (200 words or less - underline keywords)

   The objectives are ' to elucidate the mechanisms of dependence upon opiate
and of tolerance to these compounds and to define the normal functions of the
newly discovered endogenous opiate peptides.


201 HL 00002-03 LBG

Project Description:

   Major Findings:  Clonal cell lines.with morphine receptors were found and
were used to study the mechanism of. action of narcotics.  Morphine and other
narcotics were found to affect adenylate cyclase in two ways, mediated by the
opiate receptor:  (1) narcotics inhibit adenylate cyclase activity, and (2)
when cells are cultured in the presence of morphine for 12 to 48 hours an in-
crease in adenylate cyclase activity is observed which compensates for the
inhibition of enzyme activity by morphine.  Cells then have.normal CAMP levels
and appear tolerant to morphine because the increase in adenylate cyclase ac-
.tivity is approximately equal to the inhibition of enzyme activity by morphine.
However, the cells then are dependent upon morphine to maintain normal cAMP
levels.  Withdrawal of morphine, or displacement of the narcotic from the opiate
receptor by the antagonist, naloxone, reverses the inhibition and results in
the synthesis of abnormally high levels of CAMP.  Thus, dual regulation of
adenylate cyclase by narcotics accounts for narcotic dependence and tolerance.
The recently discovered endogenous opiate peptides, Met-enkephalin and
Leu-enkephalin, also were shown to be potent inhibitors of adenylate cyclase.
These results show that the endogenous opiate peptides and narcotics act as
pleiotropic regulators of other species of receptors which are coupled to the
activation of adenylate cyclase.  In this way, the opiates alter the perception
of neurons to incoming messages.

   Significance to Biomedical Research:  The biochemical basis for narcotic
dependence and tolerance has been established and the mode of action and the
normal role of the endogenous opiate peptides have been clarified.

   Proposed Course:  Further studies on the mechanism of dual regulation of
adenylate cyclase are in progress.

Publications:

1.  Sharma, Shail K., Kle,e, Werner A. and Nirenberg, Marshall: Dual regula-
  tion of adenylate cyclase accounts for narcotic dependence and tolerance.
  Proc. Natl. Acad. Sci. USA 72: 3092-3096, 1975.

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