EXPRESSION OF THE LACZ REPORTER GENE IN THE RAT BASAL FOREBRAIN, HIPPOCAMPUS, AND NIGROSTRIATAL PATHWAY USING A NONREPLICATING HERPES-SIMPLEX VECTOR

We recently demonstrated the efficacy of a nonreplicating herpes simpl ex type 1 virus construct, employing the Moloney murine leukemia virus long terminal repeat promoter, in providing long-term expression of t he lacZ gene in rat hippocampal neurons. We now report the utility of this construct in expressing the reporter gene in neurons of the basal forebrain and substantia nigra and examine the spread of the virus to other brain regions. Dorsal and ventrolateral hippocampal formation i njection of the virus resulted in numerous beta-gal-expressing cells i n the stratum pyramidale, stratum oriens, stratum lacunosum-moleculare , and stratum granulosum. Scattered cells of the medial septum/diagona l band were positively stained following direct injection into this re gion. More intense staining of the basal forebrain was observed follow ing hippocampal injection as a result of retrograde transport of the v irus as shown by PCR analysis of viral DNA. Hippocampal injection also resulted in positive cell staining in several other afferent projecti on nuclei, namely, the supramammillary bodies, dorsal and caudal Linea r raphe, and perirhinal/entorhinal cortex. Very few cells were labeled around injection sites in the striatum or substantia nigra. However, substantia nigra zona compacta cells were blue following striatal inje ction, as were pallidal neurons following nigral injection. These data demonstrate the feasibility of using this virus construct to express foreign genes such as neurotrophic factors in basal forebrain and subs tantia nigra neurons, taking advantage of retrograde transport of the virus to preserve local anatomy. (C) 1996 Academic Press, Inc.