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  • 1
    Electronic Resource
    Electronic Resource
    The effect of chronic administration and withdrawal of amphetamine on cerebral dopamine receptor sensitivity (1978)
    Springer
    Psychopharmacology 58 (1978), S. 131-136 
    Details
    ISSN: 1432-2072
    Keywords: Amphetamine ; Circling behaviour ; Dopamine ; Locomotor activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mice with a 6-hydroxydopamine induced unilateral nigro-striatal lesion received (+)-amphetamine sulphate (2.5–20 mg/kg) over a 3-month period by daily incorporation into the drinking water. During this period the circling response to apomorphine hydrochloride (0.01–0.5 mg/kg, s.c.) was increasingly suppressed in comparison to control animals, while spontaneous locomotor activity increased. Following drug withdrawal the circling response to apomorphine remained suppressed two months later. However, spontaneous locomotor activity was also reduced up to 1 month following drug removal. The dopamine content of the lesioned side of the forebrain was 25% of the intact side in control animals and was not further reduced by amphetamine administration. The dopamine content of the intact forebrain was reduced by 43% during amphetamine administration and remained 18% depressed 1 month following drug withdrawal. No changes in 5-hydroxytryptamine or noradrenaline concentrations were observed in either the intact or lesioned side. This data, while showing that chronic amphetamine treatment can induce persistent changes in dopamine receptor sensitivity, can be interpreted in terms of increased striatal receptor sensitivity or as a decreased response of dopamine receptors in the nucleus accumbens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426895
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  • 2
    Electronic Resource
    Electronic Resource
    Pharmacological characterisation of spontaneous or drug-associated purposeless chewing movements in rats (1985)
    Springer
    Psychopharmacology 85 (1985), S. 71-79 
    Details
    ISSN: 1432-2072
    Keywords: Dopamine ; Acetylcholine ; Acute dystonia ; Peri-oral behaviour ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Continuous administration of haloperidol, sulpiride, or cis-flupenthixol, but not of domperidone or apomorphine, to Wistar rats for up to 3 weeks caused an increase in spontaneous purposeless chewing movements. Treatment with physostigmine and pilocarpine, but not neostigmine, for up to 3 weeks increased chewing, whilst scopolamine decreased chewing. Metergoline and cyproheptadine, but not quipazine, increased chewing after only 1 and 7 days but not thereafter. Chewing was not altered following treatment with compounds acting on GABA or noradrenaline systems or by a range of non-neuroleptic agents inducing dystonia in man. The enhancement of chewing induced by neuroleptic and cholinomimetic drugs was reduced by acute treatment with scopolamine, and reverted to control levels following drug withdrawal. Neuroleptic-induced purposeless chewing in Wistar rats appears to be primarily influenced by cerebral dopamine and acetylcholine function and may resemble acute dystonia, rather than tardive dyskinesia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427326
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  • 3
    Electronic Resource
    Electronic Resource
    Behavioural effects mediated by unilateral nigral dopamine receptor stimulation in the rat (1984)
    Springer
    Experimental brain research 55 (1984), S. 243-252 
    Details
    ISSN: 1432-1106
    Keywords: Circling behaviour ; Substantia nigra ; Dopamine receptors ; Dopamine ; Apomorphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unilateral intranigral injections of dopamine in conscious rats pretreated with nialamide resulted in either ipsiversive or contraversive rotation depending upon the site of injection. Injection of dopamine (50 μg) into the zona compacta of the substantia nigra induced weak ipsiversive or mixed ipsiversive and contraversive rotation. Injection of dopamine (12.5–50.0 μg) into zona reticulata of substantia nigra induced only contraversive circling. Destruction of the ipsilateral medial forebrain bundle (MFB) using 6-hydroxydopamine (6-OHDA) abolished ipsiversive circling but enhanced contraversive circling produced by dopamine or apomorphine. The combination of a unilateral 6-OHDA lesion of MFB with a kainic acid or electrolesion of the ipsilateral strio-nigral and pallido-nigral pathways reduced contraversive circling to intranigral apomorphine (10 μg). Ipsiversive circling produced following intranigral injection of dopamine is dependent upon the integrity of ascending dopamine neurones. Contraversive rotation is independent of ascending dopamine pathways but is reliant upon afferent input to the substantia nigra from the striatum and/or globus pallidus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237275
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of somatostatin on dopamine sensitive adenylate cyclase activity in the caudate-putamen of the rat (1986)
    Springer
    Experimental brain research 62 (1986), S. 567-571 
    Details
    ISSN: 1432-1106
    Keywords: Adenylate cyclase ; Caudate-putamen ; Dopamine ; Somatostatin ; 6-hydroxydopamine ; Kainic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of somatostatin-14 (SRIF) on dopamine-sensitive adenylate cyclase in caudateputamen pellets was studied in naive female rats, and in rats with chemical lesions of the nigrostriatal dopaminergic tract produced by injecion of 6-hydroxydopamine, or of the caudate-putamen itself produced by injection of kainic acid 3 week earlier. In unlesioned rats somatostatin at a concentration of 10−7 moles/1 inhibited adenylate cyclase activation by submaximal concentrations of dopamine, increasing the apparent Km but not altering Emax. In 6-hydroxydopamine lesioned rats somatostatin no longer influenced adenylate cyclase activity, whereas in kainic acid lesioned rats somatostatin still increased the apparent Km for dopamine activation. The effect of somatostatin in untreated and lesioned rats is compatible with a partial competitive antagonism to dopamine. Although the data from the lesioned rats present preliminary results, the dose response characteristics and the effects in lesioned animals suggest a more complex interaction, possibly by binding of somatostatin to an inhibitory subunit of regulatory adenylate cyclase components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236035
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  • 5
    Electronic Resource
    Electronic Resource
    Dopamine and somatostatin modulated adenylate cyclase activity in the rat caudate-putamen following unilateral cortical ablation (1987)
    Springer
    Experimental brain research 68 (1987), S. 406-410 
    Details
    ISSN: 1432-1106
    Keywords: Adenylate cyclase ; Caudate-putamen ; Cortical ablation ; Dopamine ; Somatostatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Dopamine and somatostatin-14 (SRIF) were incubated with a membrane fraction of rat caudate-putamen (CP) tissue in an adenylate cyclase assay in order to examine the D-1-receptor coupled adenylate cyclase activity 5 days and 3 weeks after unilateral ablation of the left frontal and lateral cortex. Five days after decortication the ipsilateral basal and dopamine stimulated adenylate cyclase activity was increased by about 30% compared to that of the contralateral side. Three weeks after decortication no significant difference could be seen. On either side basal and dopamine stimulated adenylate cyclase activity was not significantly decreased compared to sham operated controls. Somatostatin (10-7 mol/l) reduced basal adenylate cyclase activity of the ipsilateral CP five days following lesioning and reduced the maximal stimulation induced by dopamine. The effects of somatostatin were most marked in the absence and at low concentrations of dopamine (10-7–10-6 mol/l). The effects of somatostatin in the lesioned CP were no longer apparent three weeks following surgery. These results do not favour a presynaptic localization of D-1-receptors on cortico-striate projection fibers and suggest that somatostatin is involved in the interaction of the cortico-striate and nigro-striatal projection systems and may play a role in the regulation of D-1-receptor linked adenylate cyclase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248805
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  • 6
    Electronic Resource
    Electronic Resource
    A comparison of striatal and mesolimbic dopamine function in the rat during 6-month trifluoperazine administration (1980)
    Springer
    Psychopharmacology 69 (1980), S. 227-233 
    Details
    ISSN: 1432-2072
    Keywords: Chronic neuroleptic ; Dopamine ; Supersensitivity ; Striatum ; Mesolimbic area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Previous work has shown that 6–12 months continuous trifluoperazine (TFP) administration to rats causes striatal dopamine receptor supersensitivity. We have now replicated our original findings in the striatum and report concurrent changes in mesolimbic dopamine function during chronic TFP (2.8–4.0 mg/kg/day) administration for 6 months. Initial inhibition of apomorphine-induced stereotyped behaviour, which lasted for 2 weeks after the beginning of drug administration, was replaced by an exaggerated response to apomorphine (0.5 mg/kg SC) after 6 months drug intake. Striatal dopamine sensitive adenylate cyclase activity was inhibited at 1 and 3 months, but by 6 months was enhanced compared to control values. Mesolimbic adenylate cyclase activity was inhibited after 2 weeks and thereafter returned to control levels. Dopamine-identified 3H-spiperone binding sites (Bmax) in the striatum were increased by 2 weeks, reduced at 1 month and increased again at 6 months. In mesolimbic areas Bmax was increased at 2 weeks and 1 month but thereafter returned to control levels. The dissociation constant (k D) of specific 3H-spiperone binding was increased in the striatum and mesolimbic areas at 1 month and 2 weeks respectively. The results show differential changes in dopamine function in striatal and mesolimbic brain areas during 6 months continuous TFP administration to rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00433087
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