Format

Send to

Choose Destination
Psychopharmacology (Berl). 2005 Nov;183(1):54-64. Epub 2005 Oct 22.

Delta(9)-THC administered into the medial prefrontal cortex disrupts the spatial working memory.

Author information

1
Department of Physiological Sciences, Federal University of Espírito Santo, Av. Marechal Campos, 1468, B. Maruípe, 29042-755 Vitória, ES, Brazil.

Abstract

RATIONALE:

Delta(9)-Tetrahydrocannabinol (Delta(9)-THC) disrupts working memory. The prefrontal cortex (PFC) is involved in the processing of working memory, and its medial portion (mPFC) is part of a brain reward circuit as constituted by the mesocorticolimbic dopaminergic system.

OBJECTIVE:

This study examined the involvement of the mPFC in the effects of Delta(9)-THC on spatial working memory.

METHODS:

Ten male Wistar rats well-trained in a radial arm maze and with bilateral cannula implanted in the mPFC received Delta(9)-THC intra-cortically (Delta(9)-THC IC) at doses of 0 (VEH), 32, 100 or 180 microg, 5 min before a 5-s or a 1-h delayed task in order to measure a short- or long-term spatial working memory, respectively. By contrast, 11 other animals received Delta(9)-THC intraperitoneally (Delta(9)-THC IP) at doses of 0 (VEH), 0.32, 1 or 1.8 mg/kg, 30 min before a 5-s or a 1-h delayed task. Additionally, after a 15-day washout, the effect of an IP or IC pre-exposure of Delta(9)-THC was examined by repeating both dose-effect curves in a crossover order for the routes of administration.

RESULTS:

Delta(9)-THC IP produced significantly larger number of errors at doses of 0.32 or 1 mg/kg as compared to VEH in the 1-h post-delay performance. Delta(9)-THC 100 microg IC also produced significantly larger number of errors as compared to VEH and also to the other doses (32 or 180 microg) IC in the 1-h post-delay performance. Previous exposure to Delta(9)-THC IP or IC did not significantly affect the disruptive effect of this cannabinoid.

CONCLUSIONS:

Delta(9)-THC administered directly in the mPFC impaired 1-h delayed task in the radial arm maze in a manner similar to that observed for its systemic administration, suggesting that the mPFC is involved in the disruptive effects of Delta(9)-THC on spatial working memory.

PMID:
16163518
DOI:
10.1007/s00213-005-0141-1
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center