AT2 receptors are more plentiful in the fetus and neonate. The AT2 receptor remains enigmatic and controversial – is probably involved in vascular growth. Effects mediated by the AT2 receptor are suggested to include inhibition of cell growth, fetal tissue development, modulation of extracellular matrix, neuronal regeneration, apoptosis, cellular differentiation, and maybe vasodilation and left ventricular hypertrophy.[6] In humans the AT2 subtype is found in molecular layer of the cerebellum. In the mouse is found in the adrenal gland, amygdaloid nuclei and, in small numbers, in the paraventricular nucleus of the hypothalamus and the locus coeruleus.[7]
Other poorly characterized subtypes include the AT3 and AT4 receptors. The AT4 receptor is activated by the angiotensin II metabolite angiotensin IV, and may play a role in regulation of the CNS extracellular matrix, as well as modulation of oxytocin release.[8][9][10][11][12][13][14][15]
^ abHiguchi S, Ohtsu H, Suzuki H, Shirai H, Frank GD, Eguchi S (April 2007). "Angiotensin II signal transduction through the AT1 receptor: novel insights into mechanisms and pathophysiology". Clinical Science. 112 (8): 417–28. doi:10.1042/CS20060342. PMID17346243. S2CID27624282.
^D'Amore A, Black MJ, Thomas WG (December 2005). "The angiotensin II type 2 receptor causes constitutive growth of cardiomyocytes and does not antagonize angiotensin II type 1 receptor-mediated hypertrophy". Hypertension. 46 (6): 1347–54. doi:10.1161/01.HYP.0000193504.51489.cf. PMID16286564. S2CID10812400.
^Albiston AL, Mustafa T, McDowall SG, Mendelsohn FA, Lee J, Chai SY (March 2003). "AT4 receptor is insulin-regulated membrane aminopeptidase: potential mechanisms of memory enhancement". Trends in Endocrinology and Metabolism. 14 (2): 72–7. doi:10.1016/S1043-2760(02)00037-1. PMID12591177. S2CID6481079.
^Chai SY, Fernando R, Peck G, Ye SY, Mendelsohn FA, Jenkins TA, Albiston AL (November 2004). "The angiotensin IV/AT4 receptor". Cellular and Molecular Life Sciences. 61 (21): 2728–37. doi:10.1007/s00018-004-4246-1. PMID15549174. S2CID22816307.
^Davis CJ, Kramár EA, De A, Meighan PC, Simasko SM, Wright JW, Harding JW (2006). "AT4 receptor activation increases intracellular calcium influx and induces a non-N-methyl-D-aspartate dependent form of long-term potentiation". Neuroscience. 137 (4): 1369–79. doi:10.1016/j.neuroscience.2005.10.051. PMID16343778. S2CID8280334.