1. Intravenous administration of angiotensin II reduced the adrenaline content, increased the catechol-O-methyltransferase activity, and decreased the monoamine oxidase activity of the rat hypothalamus.
2. Intraventricularly administered angiotensin II reduced the noradrenaline content to a smaller extent.
3. The change produced by intravenous administration of angiotensin might be indirectly caused by a response to angiotensin.