Involvement of dopamine D2 receptors in complex maze learning and acetylcholine release in ventral hippocampus of rats

Reversal of Clozapine Effects on Working Memory in Rats with Fimbria–Fornix Lesions

“…In previous work, we demonstrated that antagonism of D 2 receptors in the ventral hippocampus by infusions of the D 2 antagonist raclopride, causes working memory impairments in rats (Wilkerson and Levin, 1999). Umegaki et al (2001) have also demonstrated T-maze memory performance deficits after hippocampal infusion of D 2 antagonists. D 4 receptor antagonist effects of clozapine may contribute the differential effects seen in the fimbria-fornixlesioned and sham-operated rats in the current study.…”

Differential Contributions of Prefrontal and Hippocampal Dopamine D1and D2Receptors in Human Cognitive Functions

“…The finding that hippocampal D 2 binding was more related to visuospatial memory than to verbal memory might stem from the fact that verbal learning is dependent on regions other than HPC, such as anterior, lateral and superior temporal lobes, which are involved in human language, although HPC plays a central role in both types of memory (Hodges and Graham, 2001). Umegaki et al (2001) reported that injection of a D 2 receptor antagonist into HPC impaired memory performance and that the memory impairment was ameliorated by coinjection of a D 2 receptor agonist. They also found that local infusion of D 2 agonist into HPC stimulated acetylcholine release in HPC and ameliorated scopolamine-induced memory impairment (Fujishiro et al, 2005).…”

Effects of L-Dopa and Dopamine D2 Agonists on Recollection and Familiarity in Idiopathic Nondementing Parkinson’s Disease

“…In support of this proposal, there is a large body of evidence documenting the presence of D2 receptors in the hippocampus [75][76][77][78] and their involvement in memory from studies examining post-mortem tissue [27], brain imaging [76] and injecting quinpirole, a D2 receptor antagonist, into the hippocampus of rats [33].…”

“…So, for example, injecting the dopamine D1 and D2 antagonist D-AP-5 into rodent hippocampus impairs maze learning [32][33][34]; whereas administration of D1 agonists, such as piribedil and bromocriptine, and SKF 38393 and SKF 81297, promotes spatial memory in young adult rats [35,36] and aged rats [37]. In humans, l-dopa (100 mg plus 25 mg carbidopa) has also been shown to increase verbal encoding in healthy young and older adults adults, as well as stroke patients [38][39][40].…”