Peptide and protein hormones are composed of amino acids with latter being longer in length. They are synthesized in rough endoplasmic reticulum where they undergo various modifications like N terminal signal sequence removal and glycosylation to form prohormones. These prohormones are sent to golgi apparatus where they are packaged in secretory vesicles. In response to a stimulus the appropriate vesicle is released via exocytosis.
They can show regulated secretion where the hormone is stored in vesicles for a long time and then released in large amount in bursts for a proper stimulus. Sometimes they also show constitutive secretion where they are released slowly and steadily by the vesicles.
If want a direct answer it would be the decrease in mice, but if you want to get technical the decrease in grain spills caused mice to leave so that would be the indirect cause
