Increase of astrocyte apposition on <scp>GnRH</scp> neurons in early puberty onset induced by high fat diet

Puberty onset is driven by the activation of GnRH-secreting neurons and can be advanced by obesity. Astrocytes are dynamic cells that react to changes in the central nervous system environment and participate in the regulation of energy balance and reproduction. To assess the interaction of GnRH neurons and hypothalamic astrocytes during the puberty transition in HFD-treated mice, female and male mice were divided into three groups according to the diet offered at weaning: 42% high-fat diet (HFD42%), 60% high-fat diet (HFD60%), or regular diet (CHOW). The effects of HFD on reproductive tissue and fat content during the prepubertal and pubertal transition were assessed. The impact of HFD on astrocyte interaction with GnRH neurons in the medial preoptic area (MPOA) and arcuate/median eminence (ARC/ME) was assessed. HFD anticipated the first signs of puberty in both male and female mice. Furthermore, there was an increase in adipose and reproductive tissue content in early pubertal animals. Remarkably, the anticipation of puberty onset in females treated with HFD was associated with an increase in the astrocyte apposition on GnRH neurons in the MPOA. Also, there was an increase in astrocyte apposition on GnRH neurons and their fiber projections in the ARC/ME. This study suggests that the HFD-induced anticipation of puberty seems to be, at least partially, mediated by an increase in the morphological association between astrocytes and GnRH neurons in both the MPOA and ARC/EM, which may increase the excitability of GnRH neurons.