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Paradoxical Effects after Microinjection of Morphine in the Periaqueductal Gray Matter in the Rat
Abstract
Paradoxical, concurrent hyper- and hyporeactivity of a profound nature to specific stimuli occurred when 10 micrograms of morphine was microinjected bilaterally into the periaqueductal gray matter of the rat brain. Both effects at this site were dose-dependent. The hyperreactivity (to previously neutral auditory and visual stimuli) was obtained only with intracerebrally injected morphine and never with intraperitoneally injected morphine or with other opiates administered either way. Rapid tolerance to toxic doses of morphine developed at this site, as well as cross tolerance of the hyporeactivity to painful stimuli between routes (intracerebral to intraperitoneal) of morphine administration. Both the hyper- and hyporeactivity were fully reversible by intracerebral injection of naloxone in the periaqueductal gray. Thus, the periaqueductal gray appears to be a major pathway for morphine action.
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Citations
Cited by
Functional characteristics of the midbrain periaqueductal gray.
Behbehani, M. M. (1995) · Progress in Neurobiology · doi:10.1016/0301-0082(95)00009-k · Cited by 879
Antagonism of acupuncture analgesia in man by the narcotic antagonist naloxone
Mayer, D. J., Price, D. D., & Rafii, A. (1977) · Brain Research · doi:10.1016/0006-8993(77)90161-5 · Cited by 759
Central nervous system mechanisms of analgesia
Mayer, D. J., & Price, D. D. (1976) · Pain · doi:10.1016/0304-3959(76)90080-4 · Cited by 718
The C-Fragment of β-Lipotropin: An Endogenous Neuroleptic or Antipsychotogen?
Jacquet, Y. F., & Marks, N. (1976) · Science · doi:10.1126/science.185695 · Cited by 425
Self-citationSerotonin-containing neurons: their possible role in pain and analgesia
Messing, R. B., & Lytle, L. D. (1977) · Pain · doi:10.1016/0304-3959(77)90083-5 · Cited by 398
Metadata
- Authors
- Jacquet, Y. F., & Lajtha, A.
- Venue
- Science
- Published
- 1974-09-20
- Volume
- 185
- Issue
- 4156
- Pages
- 1055-1057
- ISSN
- 0036-8075 (ISSN-L)
- 1095-9203
- OpenAlex
- W2055608327
- Cited by
- 268
- References
- 0
- FWCI
- 21.84
- Type
- journal article
- Language
- en
- Open access
- closed
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- Jacquet, Y. F., & Lajtha, A. (1974). Paradoxical Effects after Microinjection of Morphine in the Periaqueductal Gray Matter in the Rat. Science. https://doi.org/10.1126/science.185.4156.1055
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