In accordance with the present invention, there are provided methods of modulating the activity of excitatory amino acid receptors using a specifically defined class of heterocyclic compounds. In one embodiment, there are provided methods of modulating metabotropic glutamate receptors. The present invention also discloses methods of treating disease using heterocyclic compounds. Diseases contemplated include cerebral ischemia, chronic neurodegeneration, psychiatric disorders, schizophrenia, mood disorders, emotion disorders, disorders of extrapyramidal motor function, obesity, disorders of respiration, motor control and function, attention deficit disorders, concentration disorders, pain disorders, neurodegenerative disorders, epilepsy, convulsive disorders, eating disorders, sleep disorders, sexual disorders, circadian disorders, drug withdrawal, drug addiction, compulsive disorders, anxiety, panic disorders, depressive disorders, skin disorders, retinal ischemia, retinal degeneration, glaucoma, disorders associated with organ transplantation, asthma, ischemia and astrocytomas. The invention further discloses methods of preventing disease conditions related to diseases of the pulmonary system, diseases of the nervous system, diseases of the cardiovascular system, diseases of the gastrointestinal system, diseases of the endocrine system, diseases of the exocrine system, diseases of the skin, cancer and diseases of the ophthalmic system. The invention also discloses pharmaceutically acceptable salt forms of heterocyclic compounds.