'downregulated' is formed from the prefix 'down-' meaning 'reduce' and the verb 'regulate', which comes from Latin 'regulare' meaning 'to control or rule'.

'regulate' comes from Latin 'regulare', which became 'regulate' in Middle English. The prefix 'down-' was added in modern scientific English to indicate reduction in activity.

Initially, 'regulate' meant 'to control or rule', but with the addition of 'down-', it evolved to mean 'to reduce or decrease the level or activity of something', especially in biological contexts.