ABSTRACT
This chapter discusses the neuroendocrine system as a part of the endocrine system, though it can be considered as a system on its own. The endocrine system plays a crucial regulatory role in the internal environment of an organism. The neuroendocrine system, as its name implies, is an integrated control system of both neural and endocrine functions. The endocrine portion of the neuroendocrine component may also be derived from the nervous system developmentally. Endocrine glands exert their effects on target tissues by secreting hormones into the circulatory system. The pituitary gland has long been considered the master gland of all endocrine subsystems and is certainly appropriate to be named the conductor of the endocrine orchestra. Environmental light-dark information is fed to the pineal gland, mostly through the retina, and is transduced into neuroendocrine signals acting at various levels. The toxic response may involve multiple endocrine malfunctions detrimental to the internal environment of the organism.
