[H-3] 7-OH-DPAT

7-OH-DPAT (7-hydroxy-2-(N,N-di-n-propylamino)tetralin) is a synthetic aminotetralin derivative that acts as a potent dopamine receptor agonist. It predominantly targets the dopamine D3 receptor subtype, though it can also activate D2 receptors at higher concentrations.

In isolated binding assays, the active R-(+)-enantiomer of 7-OH-DPAT demonstrates roughly 100- to 200-fold higher selectivity for D3 receptors over D2 receptors. It is even more selective compared to other dopamine receptor family members, exhibiting over 1,000-fold selectivity over D4 and over 10,000-fold selectivity over D1-like receptors.

For cloned human D3 receptors, 7-OH-DPAT binds with sub-nanomolar to low-nanomolar affinity (Ki = 0.5-0.8 nM). In contrast, its inhibition constant (Ki) is significantly higher at D2 receptors (=100-200 nM), D4 receptors (=1000 nM), and D1 receptors (>10,000 nM).

In preclinical neuroscience, 7-OH-DPAT is widely utilized to map D3 receptor expression and study D3-mediated signaling in mesolimbic reward pathways. It is frequently used in behavioral paradigms - such as drug discrimination, low-dose yawning induction, and hypothermia assays - as well as radiolabeled binding assays ([3H]-7-OH-DPAT).

Unlike classic dopamine agonists like apomorphine, bromocriptine, or pramipexole, 7-OH-DPAT was historically one of the earliest tools identified with high selectivity for D3 over D2 receptors. Structurally, it belongs to the aminotetralin class rather than the ergoline or benzothiazole classes typical of many non-selective antiparkinsonian agents.

While 7-OH-DPAT itself is restricted to laboratory research due to off-target D2 activation at higher doses and poor pharmacokinetic properties, several clinical drugs feature significant D3 receptor activity. Examples include the antiparkinsonian agents pramipexole and ropinirole, as well as the atypical antipsychotic cariprazine, which acts as a partial agonist at D3 and D2 receptors.