scholarly journals Effects of 3-O-Methyldopa, L-3,4-Dihydroxyphenylalanine Metabolite, on Locomotor Activity and Dopamine Turnover in Rats

2012 ◽  
Vol 35 (8) ◽  
pp. 1244-1248 ◽  
Author(s):  
Yoritaka Onzawa ◽  
Yasuhiro Kimura ◽  
Kengo Uzuhashi ◽  
Megumi Shirasuna ◽  
Tasuku Hirosawa ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Dopamine Turnover

scholarly journals Effects of sub-chronic amylin receptor activation on alcohol-induced locomotor stimulation and monoamine levels in mice

2020 ◽  
Vol 237 (11) ◽  
pp. 3249-3257 ◽  
Author(s):  
Aimilia Lydia Kalafateli ◽  
Cajsa Aranäs ◽  
Elisabet Jerlhag
Keyword(s):  
Locomotor Activity ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Receptor Activation ◽  
Dopamine Turnover ◽  
Protein Levels ◽  
Locomotor Stimulation ◽  
Term Administration ◽  
Alcohol Response ◽  
Receptor Activity Modifying Proteins

Abstract Rationale Amylin receptors consist of the calcitonin receptor (CTR) and one of three receptor activity-modifying proteins (RAMPs). The identification of amylin receptors in areas processing reward, namely laterodorsal tegmental area (LDTg), ventral tegmental area (VTA), and nucleus accumbens (NAc), has attributed them a role as reward regulators. Indeed, acute activation of amylin receptors by the amylin receptor agonist salmon calcitonin (sCT) attenuates alcohol-induced behaviours in rodents. Objectives The effects of long-term administration of sCT on alcohol-related behaviours and the molecular mechanisms underlying these processes are not yet elucidated. To fill this knowledge gap, we investigated the effects of sub-chronic sCT treatment on the locomotor stimulatory responses to alcohol in mice and the molecular pathways involved. Methods We assessed the behavioural effects of sub-chronic sCT treatment by means of locomotor activity experiments in mice. We used western blot to identify changes of the CTR levels and ex vivo biochemical analysis to detect changes in monoamines and their metabolites. Results After discontinuation for 5 days of sCT treatment, alcohol did not induce locomotor stimulation in mice pre-treated with sCT when compared with vehicle, without altering secondary behavioural parameters of the locomotor activity experiment or the protein levels of the CTR in reward-related areas in the same set of animals. Moreover, repeated sCT treatment altered monoaminergic neurotransmission in various brain areas, including increased serotonin and decreased dopamine turnover in the VTA. Lastly, we identified a differential effect of repeated sCT and acute alcohol administration on alcohol-induced locomotion in mice, where sCT initially attenuated and later increased this alcohol response. It was further found that this treatment combination did not affect secondary behavioural parameters measured in this locomotor activity experiments. Conclusions These data suggest that sub-chronic sCT treatment differentially alters the ability of alcohol to cause locomotor stimulation, possibly through molecular mechanisms involving various neurotransmitter systems and not the CTR levels per se.

Hyperlocomotion during Recovery from Isoflurane Anesthesia Is Associated with Increased Dopamine Turnover in the Nucleus Accumbens and Striatum in Mice

1997 ◽  
Vol 86 (2) ◽  
pp. 464-475 ◽  
Author(s):  
Masahiro Irifune ◽  
Tomoaki Sato ◽  
Takashige Nishikawa ◽  
Takashi Masuyama ◽  
Masahiro Nomoto ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Nucleus Accumbens ◽  
High Performance ◽  
Gas Flow ◽  
Brain Regions ◽  
Dopamine Neurons ◽  
Dopamine Turnover

Background It was recently reported that isoflurane increases dopamine release in the striatum in rats both in vivo and in vitro, and that isoflurane inhibits uptake of dopamine in the rat brain synaptosomes. However, the functional role of these effects of isoflurane on dopamine neurons is uncertain. Dopaminergic mechanisms within the nucleus accumbens and striatum play an important role in the control of locomotor activity, and a change in dopamine turnover depends essentially on a change in impulse flow in the dopamine neurons. In this study, the effects of isoflurane on locomotor activity and on dopamine turnover were investigated in discrete brain regions in mice. Methods Mice were placed in individual airtight clear plastic chambers and spontaneously breathed isoflurane in 25% oxygen and 75% nitrogen (fresh gas flow, 4 l/min). Locomotor activity was measured with an Animex activity meter. Animals were decapitated after treatments with or without isoflurane, and the concentrations of monoamines and their metabolites in different brain areas were measured by high-performance liquid chromatography. Results During the 10 min after the cessation of the 20-min exposure to isoflurane, there was a significant increase in locomotor activity in animals breathing 1.5% isoflurane but not 0.7% isoflurane. This increase in locomotor activity produced by 1.5% isoflurane was abolished by a low dose of haloperidol (0.1 mg/kg), a dopamine receptor antagonist. Regional brain monoamine assays revealed that 1.5% isoflurane significantly increased the 3,4-dihydroxyphenylacetic acid:dopamine ratio (one indicator of transmitter turnover) in the nucleus accumbens and striatum, but a concentration of 0.7% did not. This significant increase in dopamine turnover in these regions continued during 20 min after the cessation of the administration of 1.5% isoflurane. Conclusions These results suggest that isoflurane-induced hyperlocomotion during emergence may be associated with increased dopamine turnover in the nucleus accumbens and striatum.

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