caa a22 4500 469079649 CHVBK 20180323132946.0 cr unu---uuuuu 170328e19920501xx s 000 0 eng 10.1007/BF00168942 doi (NATIONALLICENCE)springer-10.1007/BF00168942 Ahlenius Sven Department of Neuropharmacology, Astra Research Centre, S-15185, Södertälje, Sweden aut Effects of the local application of 3-PPP and sulpiride enantiomers into the nucleus accumbens or into the ventral tegmental area on rat locomotor activity: evidence for the functional importance of somatodendritic autoreceptors [Elektronische Daten] [Sven Ahlenius] Summary: The present series of experiments was performed in order to determine the relative role of presynaptic and somato-dendritic autoreceptors for the sedative effects produced by systemically administered dopaminergic agonists. Thus, the effects of intracerebral administration of 3-(3-hydroxyphenyl)-N-n-propylpip-eridine (3-PPP), or sulpiride, enantiomers on spontaneous locomotor activity was investigated in rats. It was found that the local application of (−)3-PPP, but not (+)3-PPP, into the nucleus accumbens (1.25-80.0 μg, bilaterally) produced a suppression of the locomotor activity, whereas the local application of the two enantiomers into the ventral tegmental area resulted in a suppression of the locomotor activity in the same dose range. Thus, the full dopamine D2 agonist (+)3-PPP produced suppression of locomotor activity only after local application into the somato-dendritic region, suggesting that in terminal areas postsynaptic receptor stimulation effectively counterbalanced the functional consequences of presynaptic receptor stimulation. The sulpiride enantiomers both produced a suppression of locomotor activity after local application into the accumbens (0.2-5.0 μg, bilaterally). In the ventral tegmental area, however, (−)sulpiride administration (0.25.0 μg, bilaterally) resulted in an increased locomotion, whereas the (+)enantiomer produced no effect or, at the highest dose (5.0 μg), a suppression of the locomotor activity. These observations indicate that for a dopamine D2 antagonist, the postsynaptic receptor blockade in the terminal region, resulting in behavioral suppression, not only counteract compensatory effects produced via the presynaptic receptor in this region, but also to a great extent overshadow the functional consequences of somatodendritic autoreceptor blockade. The results also demonstrate that the dopamine receptor agonist [(+)3PPP], a partial agonist [(−)3-PPP] and an antagonist [(−)sulpiride], each produce distinct functional effects when considering their effects at postsynaptic dopamine receptors in projection areas of the ventral striatum together with their effects at dopamine autoreceptors in the cell body region of the ventral tegmental area. It is concluded that autoreceptor-mediated sedative effects of dopamine receptor agonists, as observed upon systemic administration in the normal animal, primarily are mediated via dopamine autoreceptors in the cell body region. Springer-Verlag, 1992 3-PPP nationallicence Sulpiride nationallicence Enantiomers nationallicence Dopamine nationallicence Autoreceptors nationallicence Localization nationallicence Locomotor activity nationallicence Rat nationallicence Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/5(1992-05-01), 516-522 0028-1298 345:5<516 1992 345 210 https://doi.org/10.1007/BF00168942 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00168942 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Ahlenius Sven Department of Neuropharmacology, Astra Research Centre, S-15185, Södertälje, Sweden aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/5(1992-05-01), 516-522 0028-1298 345:5<516 1992 345 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer