Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic cytokine that has the potential for clinical application. The biological effects of GM-CSF have been well characterized, and include stimulation of bone marrow hematopoietic stem cell proliferation and inhibition of apoptosis of hematopoietic cells. In contrast, the therapeutic effects of GM-CSF on the central nervous system in acute injury such as stroke and spinal cord injury have been reported only recently. To better understand the protective effect of GM-CSF on dopaminergic neurons in Parkinson's disease (PD), we investigated the effect of GM-CSF on the survival of dopamine neurons and changes in locomotor behavior in a murine PD model. We investigated the neuroprotective effects of GM-CSF in 1-methyl-4-phenylpyridinium (MPP+)-treated PC12 cells as well as in embryonic mouse primary mesencephalic neurons (PMNs) in vitro. To investigate the role of GM-CSF in vivo, we prepared a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) PD model, and examined the effects of GM-CSF on dopaminergic neuron survival in the substantia nigra and on locomotor behavior. Treatment with GM-CSF significantly reduced MPP+-induced dopaminergic cell death in PC12 cells and PMNs in vitro. GM-CSF modulated the expression of apoptosis-related proteins, Bcl-2 and Bax, in vitro. Furthermore, administration of GM-CSF (50 microg/kg body weight/day) in vivo for 7 days protected dopaminergic neurons in the substantia nigra and improved locomotor behavior in a mouse MPTP model of PD.

SR 121463A, a potent and selective, orally active, nonpep-tide vasopressin V 2 receptor antagonist, has been characterized in several in vitro and in vivo models. This compound displayed highly competitive and selective affinity for V 2 receptors in rat, bovine and human kidney (0.6 K i [nM] 4.1). In this latter preparation, SR 121463A potently antagonized arginine vasopressin (AVP)-stimulated adenylyl cyclase activity (K i 0.26 0.04 nM) without any intrinsic agonistic effect. In autoradiographic experiments performed in rat kidney sections, SR 121463A displaced [ 3 H]AVP labeling especially in the medullo-papillary region and confirmed that it is a suitable tool for mapping V 2 receptors. In comparison, the nonpeptide V 2 antagonist, OPC-31260, showed much lower affinity for animal and human renal V 2 receptors and lower efficacy to inhibit vasopressin-stimulated adenylyl cyclase (K i in the 10 nanomolar range). Moreover , OPC-31260 exhibited a poor V 2 selectivity profile and can be considered as a V 2 /V 1a ligand. In normally hydrated conscious rats, SR 121463A induced powerful aquaresis after intravenous (0.003-0.3 mg/kg) or oral (0.03-10 mg/kg) administration. The effect was dose-dependent and lasted about 6 hours at the dose of 3 mg/kg p.o. OPC-31260 had a similar aquaretic profile but with markedly lower oral efficacy. The action of SR 121463A was purely aquaretic with no changes in urine Na and K excretions unlike that of known diuretic agents such as furosemide or hydrochloro-thiazide. In addition, no antidiuretic properties have been detected with SR 121463A in vasopressin-deficient Brattle-boro rats. Thus, SR 121463A is the most potent and selective , orally active V 2 antagonist yet described and could be a powerful tool for exploring V 2 receptors and the therapeutical usefulness of V 2 blocker aquaretic agents in water-retaining diseases. (J. Clin. Invest. 1996. 98:2729-2738.) Key words: SR 121463A • vasopressin • nonpeptide antagonist • V 2 receptor • aquaretic