Ann E. Wilson

Psychotropic drug influences on brain acetylcholine utilization

The cholinergic antisynthesis agent HC-3 was given intraventricularly to young male rats 20–30 days old to deplete brain acetylcholine (ACh). The rate of HC-3 induced depletion of ACh was used as an index of ACh utilization. Total brain ACh was determined following various doses of chlordiazepoxide, pentobarbital, chlorpromazine, methotrimeprazine, imipramine, morphine, d-amphetamine, scopolamine, LSD-25, and phencyclidine given i.p. alone and after intraventricular administration of HC-3. It was found that psychotropic drugs have marked differential effects on the rate of HC-3 induced ACh depletion.

Effects of urine acidification on plasma and urine phencyclidine levels in overdosage

A gas chromatography‐mass Jragmentography‐electron impact (GC‐MS‐EI) assay of phencyclidine (PCP) was adapted for human plasma and urine. This assay is specific for PCP and very sensitive (approximately I ng/ml). Patients with the putative diagnosis of PCP overdosage were studied to correlate plasma and urinary levels with clinical state. Urinary PCP levels were enhanced in an acid urine, which suggests that acidification of the urine is an adjunct in the therapy of PCP overdosage.

ACETYLSECO HEMICHOLINIUM-3, A NEW CHOLINE ACETYLTRANSFERASE INHIBITOR USEFUL IN NEUROPHARMACOLOGICAL STUDIES*

Summary-Described are the synthesis and some aspects of the pharmacology of acetylseco hemicholinium-3 (acetylseco HC-3), the acetylated open ring analogue of hemicholinium-3 (HC-3). The effects of both compounds were determined in uiuo on rat brain acetylcholine (ACh), ‘Y-choline (14C-Ch) incorporation into 14C-acetylcholine (14C-ACh) and on one way jump box avoidance and escape behavior in naive and trained rats. In addition, the in vitro effects of both drugs were determined on choline acetyltransferase activity (ChAc) in rat brain. When given intraventricularly in doses of l-20 pg both compounds reduced total ACh content in the brain to a maximum of 5’0% of normal in 30-60 min. In doses of 20 pg intraventricularly, both drugs also reduced 14C-Ch incorporation into Y-ACh by 845% for acetylseco HC-3 and by 52% for HC-3. The in viva changes of ACh in the brain were correlated with the behavioral deficits induced in one way shuttle box acquisition and retention. In doses of 20 pg total intraventri~ularly, both compounds produced behavioral deficits which were greater in naive than in trained animals. Zn vitro, acetylseco HC-3 inhibited ChAc activity with an 150 of 1 x 10e5 M with Ch IO-* M and acetyl CoA 6.4 x 10m4 M, while HC-3 had no inhibitory effects. Using rat brain homogenate as the enzyme source and commercial acetyl CoA for kinetic studies, acetylseco HC-3 was shown to be a mixed inhibitor of acetyl CoA and a competitive inhibitor of Ch. The in uiuo actions of acetyiseco HC-3 are consistent with those of a ChAc inhibitor. However, it is necessary to rule out the possibility that the drug may also compete with Ch for its transport across biological membranes like its deacetylated derivative HC-3.

Brain Acetylcholine in Morphine Pellet Implanted Rats Given Naloxone

Adult male rats were implanted with intraventricular (ivt.) brain cannulae for injection of 5 Μg of acetylseco-hemicholinium-3 (acetylseco HC-3) as a means of studying acetylcholine (ACh) utilization during morphine withdrawal. Animals were made dependent by implanting s.c. two 75 mg morphine base pellets 24 hrs apart. On the 4th day animals were given 10 mg/kg of naloxone i.p. and/or 5 Μg acetylseco HC-3 ivt. and sacrificed by decapitation at various times. The brains were removed and assayed for ACh using a pyrolysis gas Chromatographie procedure. Total brain ACh before or after acetylseco-HC-3 was not altered at 5, 30, 60 and 120 but was decreased at 10 min after naloxone. These results are in sharp contrast to our previous data of enhanced brain ACh utilization in withdrawn rats made dependent to morphine by several weeks of twice daily injections. It is apparent that short term morphine pellet administration does not produce the marked neurochemical and behavioral changes of long term morphine injections.

Decreased rat brain acetylcholine utilization after heroin and cross tolerance to l-methadone.

3. E. B. Thompson and M. E. Lippman, Metabolism 23, 9. A. G. Gornall, C. J. Bardawill and M. M. David, J. biol. 159 (1974). Chem. 177, 75 1 (I 949). 4. J. P. Binette and K. Schmid, Arth. and Rhrumat. 8, 14 (1965). 10. A. J. Collins and D. A. Lewis, Biochrm. Phurmac. 20, 251 (1970). 5. J. S. Lowe and E. H. Turner, Biochem. Pharmac. 22, 2069 (1973). 6. J. S. Lowe, Biochem. Pharmac. 13, 633 (1964). 7. E. Milgrom and E. Baulieu, Biochim. biophys. Acta, 194, 602 ( 1969). 8. G. A. Bray. Analyt. B&hem. 1, 279 (1960). Il. R. R. Gala and U. Westphal, Endocrinoloyy 77, 841 (1965). 12. R. H. Persellin. G. W. Kittinger and J. W. Kendall, Am. J. Physic/. 222, 1545 (1972). 13. P. S. Hench, E. C. Kendall, C. H. Slocumb and H. F. Polley, Ann. rheum. Drs. 8, 97 ( 1949).

Relation of rat brain acetylcholine levels to duration of self-stimulation and escape behavior

Total brain acetylcholine (ACh) was assayed in groups of animals after various periods of operant responding maintained by electrical stimulation of the lateral posterior hypothalamus or of escape behavior induced by electrical stimulation of the midbrain tegmentum. Different groups of trained rats were placed in identical Skinner boxes for periods of 1 to 24 hr. The following groups were studied: controls, self-stimulators receiving electrical stimulation, escapers from brain stimulation or peripherally applied aversive stimulation, self-stimulators not receiving electrical stimulation prior to decapitation, tubocurarine-paralyzed respired rats with electrodes in the posterior-lateral hypothalamus not receiving stimulation, and a group of tubocurarine-paralyzed, respired rats receiving electrical stimulation automatically. It was found that brain stimulation decreased total brain ACh, regardless of whether the stimulation was positive, as during self-stimulation behavior, or negative, as during escape behavior. Animals that receivied positive stimulation while being paralyzed showed similar decreases in total brain ACh, but the change in ACh was smaller. No changes occurred in animals that were paralyzed that recieved no electrical stimulation. It is concluded that brain usage produced by electrical stimulation of discrete functional pathways causes a reduction of total ACh, but this is unrelated to the specific motivational properties of the electrical stimuli.