Behavioral sensitization following subchronic apomorphine treatment — possible neurochemical basis

Vaughn, Dana M.; Severson, James A.; Woodward, John J.; Randall, Patrick K.; Riffee, William H.; Leslie, Steven W.; Wilcox, Richard E.

doi:10.1016/0006-8993(90)90247-9

Cited by 21 publications

(19 citation statements)

References 30 publications

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“…Protein concentrations were determined using the BioRad Protein Assay (BioRad, Hercules, Calif., USA), after Bradford [1976]. Protein concentrations for frog brain homogenates were approximately 130 µg per assay tube, whereas rat striatal concentrations were approximately 20 µg per tube consistent with our previous reports [Severson and Wilcox, 1988;Vaughn et al, 1990;Wigal et al, 1990;Wilcox et al, 1988Wilcox et al, , 1990.…”

Section: Tissue Preparationsupporting

confidence: 70%

“…Additionally, all four compounds exhibit significantly different affinities at mammalian D1 vs. D2 receptors. As previously described [MacRae et al, 1988;Welder et al, 1988;Wigal et al, 1990;Severson et al, 1990;Vaughn et al, 1990;Wilcox et al, 1990], each assay tube contained radioligand concentrations of 3.5 nM 3 H-SCH-23390 or 0.5 nM 3 H-spiperone. Radioligands were displaced with non-radioactive drug concentrations spanning at least 4 orders of magnitude.…”

Section: Displacement Assaysmentioning

confidence: 99%

“…We used d-butaclamol (2 µM) to define non-specific binding to both receptors. Ketanserin (150 nM) was added to all tubes to prevent potential binding to 5HT 2 receptors [Severson and Wilcox, 1988;Wilcox et al, 1988aWilcox et al, , 1990Vaughn et al, 1990]. The binding assay was initiated (1 ml final volume) by adding 100 µl of homogenate.…”

Section: Saturation Binding Assaysmentioning

confidence: 99%

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Pharmacological Characterization of the D1- and D2-Like Dopamine Receptors from the Brain of the Leopard Frog, <i>Rana pipiens</i>

Chu

Wilczynski

Wilcox³

2001

Brain Behav Evol

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The pharmacological profiles of D1- and D2-like dopamine receptors were investigated for native brain receptors in the leopard frog, Rana pipiens, using direct binding assays, which characterize functional receptors rather than assess total receptor protein. We used homogenate assays of R. pipiens fore- and midbrains to determine, via saturation isotherms, that the dissociation constant, Kd, for ³H-SCH-23390 binding to the D1-like receptors was 0.29 nM, and the maximal receptor density, Bmax, was 40 fmoles/mg protein. This compares with the more than 10-fold higher density of D1 sites in rat striatum. Specific binding for the D2-like receptors was measurable using these methods with ³H-spiperone as the ligand. However, saturation of binding was not achieved. This contrasts with the > 400 fmoles/mg protein Bmax in rat striatum. Pharmacological profiles (rank order of potency of displacing drugs) for each receptor type were determined. We used non-radioactive SCH-23390, SKF-38393, sulpiride, and spiperone to displace ³H-SCH-23390 and ³H-spiperone at D1 and D2 receptors, respectively. Parallel displacement assays were performed with rat striatal controls. Results indicated that the relative rank order displacements in anuran dopamine receptors were characteristic of D1- and D2-like receptors. However, the rank orders were not identical to those in mammals. The rank order for affinity at D1-like receptors in both rats and frogs was SCH-23390 > SKF-38393 > spiperone > sulpiride. The rank order for affinity at D2-like receptors was spiperone > SCH-23390 > sulpiride > SKF-38393 in frogs, and spiperone > sulpiride > SCH-23390 > SKF-38393 in rats. SKF-38393 and spiperone had similar affinities for the ‘D1’ receptors in both species. SCH-23390 had a slightly lower affinity for the D1-like receptors in Rana, whereas sulpiride had a significantly lower affinity for Rana D1-like receptors compared to rat D1 receptors. In Rana D2-like receptors, spiperone and sulpiride were significantly less potent compared to rat. However, SCH-23390 and SKF-38393 were equally potent for the D2-like receptors in both species. The results indicate that amphibian brain dopamine receptors fall into two classes similar to the mammalian D1 and D2 subfamilies, but with binding characteristics slightly different from those typically described in mammals. This work represents the first pharmacological characterization of native brain dopaminergic receptors in an anuran amphibian. Because direct binding assays measure the initial aspect of the functional interaction between transmitter and receptor, these data provide an important complement to studies using cell expression systems.

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Section: Tissue Preparationsupporting

confidence: 70%

Section: Displacement Assaysmentioning

confidence: 99%

Section: Saturation Binding Assaysmentioning

confidence: 99%

See 1 more Smart Citation

Pharmacological Characterization of the D1- and D2-Like Dopamine Receptors from the Brain of the Leopard Frog, <i>Rana pipiens</i>

Chu

Wilczynski

Wilcox³

2001

Brain Behav Evol

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“…At present, the exact neurobiological mechanisms underlying behavioral sensitization are uncertain; however, several possibilities have been proposed, including: autoreceptor tolerance, increased DA synthesis, actions at NMDA and non-NMDA receptors, drug-induced changes in G-proteins, and conditioned activity (Robinson and Becker !986; Vaughn et al 1990;Kativas and Stewart 1991;Karler et al 1991;Rowlett et al 199t;Steketee et al 1991;Stewart and Druhan 1993). The present study was not designed to differentiate between these various explanations.…”

Section: Discussionmentioning

confidence: 76%

Ontogeny of behavioral sensitization in the rat: effects of direct and indirect dopamine agonists

et al. 1994

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In the present study, the abilities of NPA (a direct DA receptor agonist) and amphetamine (an indirect DA receptor agonist) to induce short- and long-term behavioral sensitization were assessed in 11- and 17-day-old rats (age at initial injection). Rats were injected on 4 consecutive days with amphetamine (1.0, 2.5, or 5.0 mg/kg), NPA (1.0 mg/kg), or saline. A final test day occurred either 2 days (experiment 1) or 8 days (experiment 2) later. On the test day, rats given successive agonist injections received a single injection of the same agonist again; whereas rats given successive saline injections received either amphetamine or NPA for the first time. Five minutes after injection, locomotor activity (line-crosses), stereotyped sniffing, and vertical activity were measured during a 30-min testing session. The results showed that 11- and 17-day-old rats exhibited behavioral sensitization when tested with NPA or amphetamine after a 2-day interval. In contrast, neither NPA nor amphetamine was able to sensitize the behaviors of preweanling rats when measured 8 days after initial drug treatments. Therefore, these results show that both direct and indirect DA agonists are able to induce short-term behavioral sensitization in preweanling rats, but that the mechanisms responsible for mediating long-term behavioral sensitization have not yet matured.

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“…The chronic administration of moderate to high doses of direct dopamine receptor agonists, including the D 1 /D 2 agonist, apomorphine (Mattingly and Gotsick 1989;Vaughn et al 1990;Rowlett et al 1991;Druhan et al 1993), the D 2 /D 3 agonist, QNP (Van Hartesveldt et al 1992;Einat and Szechtman 1993;Mattingly et al 1993;Szechtman et al 1994aSzechtman et al , 1994bEinat et al 1996;Szumlinski et al 1997), or the D 2 agonist, bromocriptine Wise 1992, 1993;Wise and Carlezon 1994;Wise et al 1996), produces robust locomotor sensitization. In contrast to sensitization induced by indirect dopamine agonists, sensitization induced by the repeated administration of these direct dopamine agonists is readily observed in the absence of a prolonged (>3 days) period of drug abstinence.…”

Section: Introductionmentioning

confidence: 99%

Locomotor sensitization to quinpirole in rats: effects of drug abstinence and sex

2000

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Behavioral sensitization following subchronic apomorphine treatment — possible neurochemical basis

Cited by 21 publications

References 30 publications

Pharmacological Characterization of the D1- and D2-Like Dopamine Receptors from the Brain of the Leopard Frog, <i>Rana pipiens</i>

Pharmacological Characterization of the D1- and D2-Like Dopamine Receptors from the Brain of the Leopard Frog, <i>Rana pipiens</i>

Ontogeny of behavioral sensitization in the rat: effects of direct and indirect dopamine agonists

Locomotor sensitization to quinpirole in rats: effects of drug abstinence and sex

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