Behavioral responses to and brain distribution of morphine in mature adult and aged mice
Mature adult (3-6 mo old) and aged (2 yr old) male ICR mice were injected with 10 to 100 mg/kg morphine, s.c. The ED50 values for running behavior (as measured using Stoelting activity monitors and having each mouse serve as its own control) representing 5 times control activity was approximately 7.5 mg/kg for aged mice and approximately 17.5 mg/kg for the mature adults. The ED50 values for analgesia 1 hr after morphine administration using the tail-flick method (max. response time = 8 sec) were approx. 70 mg/kg for the aged mice and 15 mg/kg for the mature adults. One hour after injecting /sup 3/H-morphine at doses of 30 and 100 mg/kg, 0.13 and 0.14% of the doses appeared in brains of aged and mature adult mice, respectively. Regional distribution of the morphine was the same for both age groups. Expressed as percent of total brain morphine, it was as follows: cortex, 30%; midbrain, 18%; cerebellum, 17%; medulla, 12%; pons, 9%; striatum, 8% and periaqueductal gray, 6%. Expressed as g morphine/g tissue for the 2 doses, the distribution was; periaqueductal gray, 30 and 80; striatum, 9 and 34; medulla, 6 and 20 pons; 5 and 19; cerebellum, 4 and 13; midbrain 2.5 and 8.5 and cortex, 2 and 8. These results suggest that the differences in response to morphine by the two age groups were due to age-related differences in opioid receptor populations and/or affinities.
- Research Organization:
- Univ. of Mississippi Medical Center, Jackson
- OSTI ID:
- 5275271
- Report Number(s):
- CONF-8604222-; TRN: 86-030565
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
MORPHINE
METABOLISM
TISSUE DISTRIBUTION
AFFINITY
AGE DEPENDENCE
BEHAVIOR
BIOLOGICAL MODELS
BRAIN
MICE
RECEPTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALKALOIDS
ANALGESICS
ANIMALS
BODY
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DISTRIBUTION
DRUGS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
NARCOTICS
NERVOUS SYSTEM
OPIUM
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RODENTS
VERTEBRATES
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)
550501 - Metabolism- Tracer Techniques