What hormone stimulates the release of luteinizing hormone by the anterior pituitary?

The hypothalamus releases GnRH (gonadotropin-releasing hormone) which stimulates the anterior pituitary gland to release LH (luteinizing hormone) and FSH (follicle-stimulating hormone). GnRH stimulates the LH burst in response to positive feedback from increasing estrogen levels.
fsh is secreted by anterior pituitary which triggers the growth of 6-12 follicles each cycle.