Dopamine Receptors: D1 and D5 Receptors

D1 and D5 belong to the D1-like receptor family. Their signalling generally increases cyclic AMP through Gs or Golf proteins. D1 receptors are important in prefrontal networks supporting working memory and other cognitive functions. Experimental findings show that both insufficient and excessive D1 stimulation can impair particular tasks.

Dopamine acts through five recognised receptor subtypes: D1, D2, D3, D4 and D5. They are proteins that convert chemical binding into changes inside a cell. D1-like and D2-like families use different signalling pathways, but their overall effects depend on the cells and networks in which they operate.

These results do not establish a simple ideal dopamine level for an individual. D5 has a different distribution and is less clearly understood clinically. Some antipsychotics bind to D1-like receptors, but D1 blockade is not an established explanation for antipsychotic efficacy. Trials of selective D1 antagonism did not establish an effective schizophrenia treatment. Research continues into ways of modifying these receptors to improve cognition, while recognising that benefits observed in experimental systems may not translate directly into routine clinical care.

D1-related working-memory findings are often described by an inverted-U curve: performance can worsen at either extreme of stimulation. This relationship depends on the task and biological setting. It supports interest in carefully targeted modulation, while explaining why simply increasing or blocking D1 activity is unlikely to provide a universal cognitive treatment for everyone with schizophrenia.

Further reading: Research record 10739409; Research record 17277774; Research record 8584611; Research record 8935801.