The isolated bovine adrenocortical cells are prepared aseptically by the use of collagenase and deoxyribonuclease. The isolated cells are suspended in Ham F-10 medium containing 5% fetal calf serum, 10% newborn calf serum, 2.5% horse serum and antibiotics. The seeded cells are cultured at 37°C in a humidified atmosphere of 5% CO2 in air. Steroidogenic activity for ACTH reached the maximum in the 2 to 3-day primary cultured cells; the maximum response to ACTH in these cells is more intense than that in freshly isolated bovine adrenocortical cells. The primary cultured cells have prostaglandin, muscarinic, ATP and β-adrenergic receptors that are linked to steroidogenesis in addition to ACTH and aldosterone receptors. Thus primary cultured bovine adrenocortical cells are a useful tool to study these receptors and the intracellular events that are associated with the receptors. We also demonstrated that the fura 2 loaded primary cultured monolayer cells on glass cover slips provide us much more information than suspended cells in the study of intracellular Ca2+ mobilization in adrenocortical cells.
Various brain imaging techniques have become available in the past decade. These include techniques to evaluate brain structure using X-ray computerized tomography or magnetic resonance imaging and techniques to assess brain functional activities (cerebral blood flow, brain energy metabolism and brain protein synthesis) using positron emission tomography (PET). PET also makes it possible for the first time to evaluate the states of various types of neurotransmitter receptors, such as dopamine D2 and D1, serotonin 5-HT2, muscarinic cholinergic, opiate, benzodiazepine and histamine H1, and to determine the state of monoamine oxidase (A and B) under in vivo conditions. These techniques cannot only be used to map “brain neurochemistry” in normal human beings, but they will also increase our knowledge by demonstrating neurochemical abnormalities in a wide range of neurological and psychiatric disorders or those that happen during normal aging. The PET techniques may be applicable to the development of new drugs in the pharmaceutical industry. We have been exploring the methodology of using 11C-labeled antagonists for mapping functional neurotransmitter receptors in human brain directly and noninvasively by PET. The present review article provides an outline of the conceptual and methodological progress over the past several years that has made it possible to visualize neurotransmitter receptors in the living human brain by PET on the basis of our original work.