Unilateral injection of morphine into the nucleus accumbens induces akinesia and catalepsy, but no spontaneous muscular rigidity in rats
- 19 Downloads
The role of the nucleus accumbens in the generation of the signs of morphine-induced “catatonia”, namely akinesia, catalepsy and muscular rigidity, was studied in rats. Morphine was injected into the nucleus accumbens and either spontaneous locomotor activity or catalepsy or activity in the electromyogram of the gastrocnemius-soleus muscle, signalling the appearance of rigidity, were recorded.
Unilateral injections of 5 μg of morphine induced a decrease of locomotor activity and weak catalepsy; 15 μg of morphine completely abolished locomotor activity (akinesia) and produced a very pronounced catalepsy. All these effects were antagonized by naloxone (2 mg/kg i.p.). Injections of morphine into the nucleus accumbens did not induce muscular rigidity. In contrast, injection of morphine (15 μg) into the head of the caudate nucleus, which induced a pronounced muscular rigidity, did not noticeably alter the locomotor activity nor did it produce catalepsy.
Our results suggest that 1) the nucleus accumbens is relevant for systemically administered morphine to produce akinesia and catalepsy, but is not noticeably involved in the development of muscular rigidity; 2) they provide evidence that morphine-induced catalepsy is largely due to a strong akinesia, and that muscular rigidity, observed after morphine administration, does not contribute to positive scores in the catalepsy test.
Key wordsAkinesia Catalepsy Caudate nucleus Morphine Muscular rigidity Nucleus accumbens
Unable to display preview. Download preview PDF.
- Andén N-E, Johnels B (1977) Effect of local application of apomorphine to the corpus striatum and to the nucleus accumbens of the reserpine-induced rigidity in rats. Brain Res 133:386–389Google Scholar
- Costall B, Naylor RJ (1974) On catalepsy and catatonia and the predictability of the catalepsy test for neuroleptic activity. Psychopharmacologia (Berlin) 34:233–241Google Scholar
- Costall B, Fortune DH, Naylor RJ (1978) Involvement of mesolimbic and extrapyramidal nuclei in the motor depressant action of narcotic drugs. J Pharm Pharmacol 30:566–572Google Scholar
- Dill RE, Costa E (1977) Behavioural dissociation of the enkephalinergic systems of nucleus accumbens and nucleus caudatus. Neuropharmacol 16:323–326Google Scholar
- Dunstan R, Broekkamp CL, Lloyd KG (1981) Involvement of caudate nucleus, amygdala or reticular formation in neuroleptic and narcotic catalepsy. Pharmacol Biochem Behav 14:169–174Google Scholar
- Fifková E, Maršala J (1967) Stereotaxic atlases for the cat, rabbit and rat. In: Bureš J, Petran M, Zachar J (eds) Electrophysiological methods in biological research. Academic Press, New York LondonGoogle Scholar
- Havemann U, Winkler M, Kuschinsky K (1980) Opioid receptors in the caudate nucleus can mediate EMG recorded rigidity in rats. Naunyn-Schmiedeberg's Arch Pharmacol 313:139–144Google Scholar
- Havemann U, Winkler M, Genç E, Kuschinsky K (1981) Effects of striatal lesions with kainic acid on morphine-induced “catatonia” and increase of striatal dopamine turnover. Naunyn-Schmiedeberg's Arch Pharmacol 317:44–50Google Scholar
- Kuschinsky K, Hornykiewicz O (1972) Morphine catalepsy in the rat: relation to striatal dopamine metabolism. Eur J Pharmacol 19:119–122Google Scholar
- Pert A (1977) Central sites involved in opiate actions. In: Fishman J (ed) The bases of addiction. Berlin, Dahlem Konferenzen, pp 299–332Google Scholar