Neuron- and microglial specific immunoexpression in steroid-independent male sexual behaviour in castrated B6D2F1 male mice

Sexual behaviour is the sine qua non for procreation for several species and is traditionally viewed to be regulated by sex steroid hormones. However, several species exhibit steroid-independent sexual behaviour, and its molecular understanding is only beginning to be uncovered. We do not yet have a cell-specific understanding of the roles non-neuronal cells play in this phenomenon. Forty B6D2F1 hybrid male mice underwent orchidectomy and some of them exhibited consistent ejaculatory reflexes at least 62 weeks post-orchidectomy over 11 sexual behaviour tests (>180 minutes each), defined as steroid-independent (SI) maters (21.80%), and those that do not, defined as SI non-maters (25%). Using flow cytometry, we compared the preoptic area immunoexpression in NeuN+ neurons and Iba1+ microglia between SI maters and SI non-maters (n = 6 per group). We found neuronal immunoexpression up-regulated for amyloid precursor protein and androgen receptor, as well as down-regulated for glucocorticoid receptor. In conjunction, microglial immunoexpression of amyloid precursor protein up-regulated. These data suggest there are cell-specific immunoexpression changes including a role of non-neuronal cells in steroid-independent male sexual behaviour. Graphic abstract