γ-Aminobutyric acid (GABA) is a nerve transmitter in the brain that has many functions that are not clearly understood. One such activity is control of secretion of the sex hormone prolactin from the...

γ-Aminobutyric acid (GABA) is a nerve transmitter in the brain that has many functions that are not clearly understood. One such activity is control of secretion of the sex hormone prolactin from the pituitary gland. Control of prolactin secretion by other nerve transmitters, such as dopamine, is thought to be exerted through cyclic nucleotides, cAMP and cGMP. Therefore, Apud and coworkers † measured cGMP levels in two sites—one in the cerebellum of the central nervous system and one in the anterior pituitary gland—in response to three different GABA stimulants, ethanolamine-O-sulfate (EOS), aminooxyacetic acid (AOAA), and muscimol (M) (the data are in Table D-22, Appendix D). Is there evidence that activation of the GABAergic nervous system with these three agonists affects cGMP?

Table D-22