In the retina, dopaminergic amacrine (interplexiform) cells establish multiple synapses on the perikarya of AII amacrines, the neurons that distribute rod signals to on- and off-cone bipolars. We used triple-label immunocytochemistry and confocal microscopy to identify the receptors contained within the postsynaptic active zone of these synapses in both mouse and rat retinas. We found that at t...

Dopaminergic signalling is established as playing an important role in novelty related modulation of hippocampal memory. Two recent studies have identified the noradrenergic fibres originating in the locus coeruleus as an additional source of neurotransmitter acting on dopaminergic receptors in the hippocampus.

The midbrain dopaminergic system is a key element in the control of motor activity, cognition, and the motivational effects of drugs of abuse, including nicotine. In this issue of Neuron, Drenan et al. find that alpha6-containing nicotinic acetylcholine receptors might selectively activate mesolimbic and mesostriatal dopaminergic neurons, enhancing striatal dopamine release and its behavioral c...

Schizophrenia involves dysregulation in dopaminergic transmission. Studies show heightened presynaptic striatal dopaminergic function and elevated striatal D(2)/D(3) receptor density in the brain. Cognitive impairments result from hypostimulation of D(1) receptors and are associated with dysfunction in the prefrontal cortex. Here we discuss relevant positron emissions tomography (PET) studies a...

Dopamine receptors were examined by Scatchard analysis in the striatal and olfactory tubercle regions of 11 inbred mouse strains. Simultaneous determinations of the binding characteristics of 3H-labeled 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (ADTN), a dopaminergic agonist, and [3H]spiroperidol, a dopaminergic antagonist, were examined. Among the 11 strains, the equilibrium dissocia...

Brain dopaminergic transmission is a critical component in numerous vital functions, and its dysfunction is involved in several disorders, including addiction and Parkinson's disease. Responses to dopamine are mediated via G protein-coupled dopamine receptors (D1-D5). Desensitization of G protein-coupled receptors is mediated via phosphorylation by members of the family of G protein-coupled rec...

The mammalian mesopontine tegmentum (MPT) contains two cholinergic nuclei, the pedunculopontine tegmental nucleus (PPTg) and the laterodorsal tegmental nucleus (LDTg). These provide the cholinergic innervation of, among other brain areas, the dopaminergic A9 and A10 cell groups. Their axons are thus the source of endogenous acetylcholine (ACh) acting on somato-dendritic acetylcholine receptors ...

Antipsychotic drugs currently in use have been developed as antidopaminergic agents; that is, normalization of psychotic symptoms occurs through a reduction in dopaminergic activity, usually by blockade of postsynaptic dopamine receptors. Based on this current understanding of the mechanism of action of antipsychotic drugs, it is suggested that one physiological role of the dopaminergic system ...

Orexins are associated with drug relapse in rodents. Here, we show that acute restraint stress in mice activates lateral hypothalamic (LH) orexin neurons, increases levels of orexin A and 2-arachidonoylglycerol (2-AG) in the ventral tegmental area (VTA), and reinstates extinguished cocaine-conditioned place preference (CPP). This stress-induced reinstatement of cocaine CPP depends on type 1 ore...

Dopamine receptors are responsible for diverse effects within and outside the central nervous system. The five dopamine receptors that have been cloned (DIA, D1B also known as D5, D2, D3, and D4) belong to two major families; the D1 like and D2 like dopamine receptors. The D1 like receptors are linked to the stimulation while D2 like receptors are linked to the inhibition of adenylyl cyclase. T...