A comparison between the effects of morphine on the rewarding and aversive properties of lateral hypothalamic and central gray stimulation

Schenk, Susan; Williams, Terrence T.; Coupal, A.; Shizgal, Peter

doi:10.3758/bf03337473

Cited by 10 publications

(3 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This experiment confirms a number of previous reports (Esposito and Kornetsky 1977;Koob et al 1975;Liebman and Segal 1976a, b;Lorens 1976;Lorens and Mitchell 1973;Schenk et al 1980) which found that lst-day ICS facilitation with morphine is rare and is relatively weak when it does appear, even when low doses are used. The largest "Day 1" effect of morphine was observed in the 3 mg/kg morphine group at 3 h post-injection (113__8% of baseline; see Fig.…”

Section: Resultssupporting

confidence: 80%

“…These effects include catalepsy (Moleman et al 1978), analgesia (Kelly and Franklin 1984), and hyperthermia (Gunne 1960;Thornhill et al 1978). However, time course studies show that peak ICS facilitation by morphine (in the form of both rate increases and threshold decreases) is usually delayed until several hours after drug injection (Broekkamp et al 1976;Lorens and Mitchell 1973;Lorens 1976;Schenk et al 1980; Experiments 1-2). This delay is often observed even at doses which are too low to produce sedation.…”

Section: Methodsmentioning

confidence: 99%

“…This raises doubts as to the direct involvement of the opiate receptor in maintaining morphine-induced ICS facilitation. Moreover, whereas the drug is maximally absorbed into the CNS by 60 rain after subcutaneous administration (Hipps et al 1976;Miller and E1-liott 1955;Mul~ 1971) and produces changes in central neural activity with an even shorter latency (Nowycky et al 1978), time course experiments show that its facilitatory effect on ICS usually does not peak until several hours post-injection (Broekkamp et al 1976;Lorens 1976;Lorens and Mitchell 1973;Schenk et al 1980). Finally, the maximal facilitation produced by a fixed daily dose of morphine is not usually seen until several days of drug administration have elapsed (Esposito and Kornetsky 1977;Hand and Franklin 1985;Koob etal.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Associative factors in the effects of morphine on self-stimulation

Hand

Franklin

1986

Psychopharmacology

View full text Add to dashboard Cite

These experiments tested the hypothesis that the suppressing and facilitating effects of morphine on intracranial self-stimulation (ICS) (measured 1 h and 3 h post-injection, respectively) are influenced by associative, non-pharmacological factors. Experiment 1 confirmed previous demonstrations that the facilitation of ICS by morphine (10 mg/kg) develops with repeated drug exposures. Once ICS facilitation had developed, the effect was mimicked by saline injection in most subjects. In a separate group of animals, previous exposure to morphine in the home cage prevented drug-induced facilitation of ICS. Tolerance to ICS suppression developed after repeated pairings of the drug and the ICS chambers, but not when the drug had previously been received in the home cage. Experiment 2 examined the effect of low (0.3, 1, 3 mg/kg) doses of chronic morphine on ICS. Facilitation was observed with 1 and 3 mg/kg, but only after repeated testing. Naloxone (0.1 and 1 mg/kg) failed to reverse facilitation in a number of these subjects. In Experiment 3, animals receiving their daily injections of morphine were allowed to self-stimulate only at 3 h post-injection (when ICS facilitation is usually maximal), rather than at 1 h and 3 h post-injection. ICS facilitation was not observed, even with repeated testing. These data indicate that the facilitation of ICS by morphine is the outcome of a learned association between drug administration and the ICS procedure, rather than the invariable result of opiate receptor activation. Repeated exposure to morphine is required for the initial establishment of ICS enhancement, but the subsequent expression of this behavior is not directly related to opiate receptor activity.

show abstract