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Neurotensin injected into the nucleus accumbens blocks the psychostimulant effects of cocaine but does not attenuate cocaine self-administration in the rat.

Abstract：

:The neuropeptide neurotensin (NT) has been shown to modulate mesolimbic dopaminergic activity. Neurotensin injected into the VTA produces motor stimulation and release of dopamine in the nucleus accumbens. In contrast, when neurotensin is administered into the nucleus accumbens, it produces neuroleptic-like effects such as attenuation of the locomotor activity elicited by psychostimulants. In the present study, the hypothesis that neurotensin injected into the nucleus accumbens might modulate the psychostimulant and reinforcing actions of cocaine was tested. In experiment one, rats were trained to self-administer cocaine intravenously on an FR5 schedule of reinforcement. Following the establishment of baseline responding, rats were implanted with bilateral cannulae in the nucleus accumbens. One week later, rats were injected into the nucleus accumbens with various doses of neurotensin (4.2, 8.4 and 16.7 micrograms, total doses bilaterally) immediately prior to the self-administration session. No significant effects were found with any of the doses of neurotensin tested on the self-administration of cocaine. However, in experiment 2, neurotensin at doses of 4.2 and 16.7 micrograms injected into the nucleus accumbens significantly reduced the locomotor activation induced by an acute injection of cocaine (15 mg/kg i.p.) and a dose of 16.7 micrograms attenuated the locomotor activation induced by amphetamine (0.75 mg/kg i.p.). Thus, neurotensin in the nucleus accumbens appears to specifically modulate the acute locomotor activating properties of cocaine but not cocaine self-administration. Different mechanisms by which NT interacts with dopamine in the nucleus accumbens may provide a means of selectively altering psychostimulant motor actions without affecting psychostimulant reinforcement.

journal_name

Brain Res

journal_title

Brain research

authors

Robledo P,Maldonado R,Koob GF

doi

10.1016/0006-8993(93)90808-z

subject

Has Abstract

pub_date

1993-09-17 00:00:00

pages

105-12

issue

1-2

eissn

0006-8993

issn

1872-6240

pii

0006-8993(93)90808-Z

journal_volume

622

pub_type

杂志文章

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Neurotensin injected into the nucleus accumbens blocks the psychostimulant effects of cocaine but does not attenuate cocaine self-administration in the rat.