Complex sentence: This is achieved specifically through changes in GnRH production and its subsequent promtion of the secretion into the bloodstream of LH, a pituitary hormone critical for reproductive function and behavior.
Split into simpler sentences: This is achieved specifically through changes in the production of the hormone GnRH. GnRH in turn transits to the pituitary where it promotes the secretion into the bloodstream of LH, a pituitary hormone critical for reproductive function and behavior.