Abstract Granulovacuolar degeneration (GVD) is a di- agnostic neuropathological feature of Alzheimer’s disease (AD). In some neurons, apoptosis has been hypothesized to be a primary mechanism causing neuronal cell death in AD. In this study we investigated CA1 neurons with GVD in AD and Down’s syndrome (DS) brain. We demon- strated that activated caspase-3 and a caspase-cleaved cleavage product of the amyloid precursor protein (cAPP) are co-localized in GVD granules, and that these same cells often show nuclear DNA damage. In contrast, acti- vated caspase-8 is present in the cytoplasm but not within the granules of GVD neurons. A caspase-cleavage prod- uct of fodrin that accumulates in many AD and DS neu- rons is not present in GVD granules. These data support a role for the activation of apoptotic mechanisms in selec- tive compartments exhibiting GVD. Keywords Granulovacuolar degeneration · Activated caspase-3 · Caspase-cleaved amyloid precursor protein · Alzheimer’s disease · Down’s syndrome Introduction Granulovacuolar degeneration (GVD) is a neuronal intra- cytoplasmic vesicle measuring 1–5 μm in diameter, with a central dark granule. GVD is primarily found within pyra- midal cells of the hippocampus and is easily detected with hematoxylin and eosin staining and by silver impregna- tion, where the granule is intensely stained. In non-de- mented elderly patients, GVD is rare; however, in Alzhei- mer’s disease (AD) patients, there is a marked increase in GVD. Thus, extensive GVD in hippocampal pyramidal neurons may contribute to neuron death and is a neuro- pathological feature of AD (for review see [1]). GVD granules are suggested to arise from microautophagy and may be formed through lysosomal autophagy of intraneu- ronal substances [10]. However, molecular events in GVD-containing neurons are poorly understood. Amyloid β-protein (Aβ), a 39- to 43-amino acid pep- tide, may play an important role in the pathogenesis of AD, and is a principal constituent of senile plaques. Aβ is a proteolytically derived fragment from an integral mem- brane protein termed amyloid precursor protein (APP). The formation of Aβ and its subsequent deposition in se- nile plaques are viewed by many as the initiating events leading to a cascade of pathological changes resulting in AD (for review see [14]). However, Aβ may not be the only neurotoxic fragment of APP. Recently, the APP C-terminal fragment produced by the cell death protease, caspase, has been reported to have pro-apoptotic activity and may be involved in the neuronal death associated with AD [4, 7]. We have examined caspase-cleaved APP (cAPP) expression in AD and aged control brain and found that cAPP immunoreactivity was detected in the granules resembling GVD granules of CA1 pyramidal neurons in AD brain (Zhao, Su, Head, Cummings, and Cotman; Accumulation of caspase cleaved amyloid pre- cursor protein represents an early neurodegeneration event in aging and in Alzheimer’s disease; in preparation). Apoptosis may be a primary mechanism leading to neuronal cell death (for review see [3]). Multiple lines of evidence indicate that caspases are essential in apoptotic cascades. Caspase-3, -8, etc., normally exist in the cytoso- lic fraction of cells as an inactive precursor that is acti- vated by enzymatic cleavage during apoptosis. Activated caspase-3 consists of p18 and p12 sub-units that are de- rived from the 32-kDa pro-enzyme (pro-caspase-3). Sev- eral studies suggest that caspase-3 activation is both nec- essary and sufficient to trigger apoptosis. Thus, caspase-3 has properties of a cell death executioner protease (for re- view see [9]). We have recently shown that activated cas- pase-3 immunoreactivity in neurons, astrocytes, and blood vessels is elevated in AD, and exhibits a high de- gree of co-localization with neurofibrillary tangles and se- nile plaques. Furthermore, we and others also found acti- Joseph H. Su · J. Patrick Kesslak · Elizabeth Head · Carl W. Cotman Caspase-cleaved amyloid precursor protein and activated caspase-3 are co-localized in the granules of granulovacuolar degeneration in Alzheimer’s disease and Down’s syndrome brain Acta Neuropathol (2002) 104 : 1–6 DOI 10.1007/s00401-002-0548-2 Received: 7 January 2002 / Revised: 20 March 2002 / Accepted: 22 March 2002 / Published online: 9 May 2002 EXPRESS COMMUNICATION J.H. Su (✉) · J.P. Kesslak · E. Head · C.W. Cotman Institute for Brain Aging and Dementia, University of California at Irvine, Irvine, CA 92697-4540, USA e-mail: josephsu@uci.edu, Tel.: +1-949-8246324, Fax: +1-949-8242071 © Springer-Verlag 2002