The pharmacology of neurokinin receptors in addiction: prospects for therapy

Figures & data

Figure 1 Neurokininergic projections in the reward pathway.

Notes: Neurokininergic projections are thought to facilitate the reward pathway. Intra-Hb SPergic interneurons facilitate reward. SPergic projections from Hb to VTA and IPN exist; however, the role of the IPN is not well understood (near VTA, not pictured). The VTA also receives SP from the NAc. The NAc additionally projects SP to the NBM. An intra-AMG SP fiber likely exists; however, its termination neuron is undetermined.
Abbreviations: Hb, habenula; VTA, ventral tegmental area; IPN, interpeduncular nucleus; NAc, nucleus accumbens; NBM, nucleus basalis magnocellularis or nucleus basalis of Meynert; AMG, amygdala; SP, substance p.

Table 1 IC₅₀ values of the three primary endogenous neurokinin ligands for the three primary neurokinin receptors

Endogenous ligand	Receptor
	NK1R	NK2R	NK3R
Substance P	0.19±0.02	100±39	67±19
Neurokinin A	20±7	0.32±0.07	28±3
Neurokinin B	63±13	5.5±3.7	0.37±0.03

Notes: SP has the greatest functional activity at the NK₁R, NKA at the NK₂R, and NKB at the NK₃R. All values are in nM. Reproduced with permission from Ingi T, Kitajima Y, Minamitake Y, Nakanishi S. Characterization of ligand-binding properties and selectivities of three rat tachykinin receptors by transfection and functional expression of their cloned cDNAs in mammalian cells. J Pharmacol Exp Ther. 1991;259(3):968–975.¹²¹

Abbreviations: IC₅₀, half maximal inhibitory concentration; NK₁R, neurokinin receptor 1; NK₂R, neurokinin receptor 2; NK₃R, neurokinin receptor 3; SP, substance p; NKA, neurokinin A; NKB, neurokinin B.

IngiTKitajimaYMinamitakeYNakanishiSCharacterization of ligand-binding properties and selectivities of three rat tachykinin receptors by transfection and functional expression of their cloned cDNAs in mammalian cellsJ Pharmacol Exp Ther199125939689751662278

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