The branch of biology which focuses on the relationship between the endocrine and the nervous system is termed as neuroendocrinology. The regulation of the activity of the hormones by the brain is studied within this field. The physiological processes in the body are regulated by a process known as neuroendocrine integration, wherein the endocrine and nervous system function together. The major neuroendocrine systems in the body are Hypothalamic–pituitary–adrenal axis (HPA axis), Hypothalamic–pituitary–thyroid axis (HPT axis), Hypothalamic–pituitary–gonadal axis (HPG axis) and Hypothalamic–neurohypophyseal system. GPCRs are G protein-coupled receptors, which can bind to numerous neuropeptides. This book is a compilation of chapters that discuss the most vital concepts and emerging trends in the field of neuroendocrinology. It presents the complex subject of neuropeptide GPCRs in the most comprehensible and easy to understand language. The extensive content of this book provides the readers with a thorough understanding of the subject.