Glucagon-like peptide-1 (GLP-1) increases in plasma and colon tissue prior to estrus and circulating levels change with increasing age in reproductively competent Wistar rats.

•Increased GLP-1 levels were found in plasma and colon tissue during proestrus.•Reduced stomach contents were recorded on the morning of estrus.•High GLP-1 at proestrus may indicate increased satiety leading into estrus.•Plasma and colon PYY unchanged during estrous cycle; possible differential PYY/GLP-1 secretion.•Increasing age affects GLP-1 regulatory control in reproductively competent females.