Neurons that synthesize and secrete Gnrh1 (gonadotropin releasing hormone 1; also known as Lhrh) integrate and control peripheral and central aspects of reproduction, including the onset of puberty. The hormone is produced by a small and diffuse population of neurons scattered in the rostral hypothalamus and medial preoptic area (MPOA) and in the basal forebrain, including the septum and diagonal band of Broca. In this transgenic strain, the mouse Gnrh1 promoter drives tissue-specific expression of cre recombinase in GNRH1-expressing neurons. When these mice are bred with mice containing a loxP-flanked sequence, Cre-mediated recombination results in deletion of the floxed sequences in the Cre recombinase-expressing tissues of the offspring. Homozygotes are viable and fertile and do not display any gross physical or behavioral abnormalities. When crossed with Gt(ROSA)26Sortm1(EYFP)Cos mutant mice (see Stock No.006148) GNRH1-expressing neurons also express EYFP. Injection of conditional pseudorabies virus (e.g. PRV Ba2001 carrying a floxed stop EGFP) can alternatively be used to identify neuronal networks associated with the gene