Intracerebroventricular responses to neuropeptide γ in the conscious rat: characterization of its receptor with selective antagonists

Abstract

1 The cardiovascular and behavioural effects elicited by the intracerebroventricular (i.c.v.) administration of neuropeptide y (NPy) in the conscious rat were assessed before and 5 min after i.c.v. pretreatment with antagonists selective for NKI (RP 67,580), NK2 (SR 48,968)

Cardiovascular and behavioural effects of intracerebroventricularly administered tachykinin NK3 receptor antagonists in the conscious rat

“…In the rat isolated portal vein, R820 is a potent NK 3 receptor antagonist (pA 2 = 7.60) with low affinity for the NK 1 and NK 2 receptors (Regoli et al , 1994b). Indeed, R820 did not block the central cardiovascular and behavioural effects induced by the NK 1 receptor selective agonist [Sar 9 , Met (O 2 ) 11 ]SP (this study) and by NPγ which acts partly through the activation of central NK 2 receptors (Picard & Couture, 1996). SR142801 seems to interact selectively with NK 3 receptors since pretreatment with a cocktail of antagonists for both NK 1 (RP67580) and NK 2 (SR48968) receptors failed to inhibit its cardiovascular effects.…”

Different Subtypes of Tachykinin NK1 Receptor Binding Sites Are Present in the Rat Brain

“…There is also evidence for a release of NKA and NPK in the brain (Diez‐Guerra et al, 1988), and even when used in rather low concentration, these peptides as well as NPγ were shown to induce different central biological responses. These peptides act on NK 2 receptors in peripheral tissues (Burcher et al, 1991), and this seems also to be the case for some central NKA or NPγ‐evoked responses that were selectively antagonized by the NK 2 receptor antagonist SR 48968 (Martini‐Luccarini et al., 1996; Picard and Couture, 1996; Steinberg et al, 1998). Direct evidence for the presence of these receptors in brain tissues has recently been reported, but these receptors were observed in only limited density in the septal area (Steinberg et al, 1998).…”

Presence of NK2 binding sites in the rat brain

“…Interestingly, in these latter areas, and in contrast with observations in other hippocampal sites, [ 125 I]NPγ labeling appeared to be resistant to the NK 2 antagonist L‐659877. As also reported, some central responses induced by local applications of NPγ are resistant to the action of both NK 2 and NK 1 antagonists (Picard and Couture 1996). Finally, the selective NK 2 antagonist [ 3 H]GR 100679 has also been used in autoradiographic studies performed on neonatal and adult rat brains (Hagan et al .…”