Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Dopamine. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

Nigral and striatal dopamine release under sensory stimuli

Abstract: SEVERAL groups have demonstrated the presence of a dopamine (DA)-sensitive adenylate cyclase in the substantia nigra. This adenylate cyclase is associated with postsynaptic dopaminergic receptors1–3, supporting the hypothesis of a dendritic release of DA originally suggested by Bjorklund and Lindvall4. Other reports provided further arguments in favour of this hypothesis. Exogenous 3H-DA, taken up in slices of the rat substantia nigra, was shown to be released by potassium through a calcium-dependent process5. Furthermore, spontaneous and evoked release of 3H-DA has been demonstrated in vivo in the cat substantia nigra6. The increase of 3H-DA release in the substantia nigra induced by amphetamine (10−6 M) or benztropine (10−6 M) is associated with a reduction of the transmitter release from nerve terminals in the ipsilateral caudate nucleus, suggesting a decreased activity of the nigrostriatal dopaminergic7 neurones. A similar phenomenon was seen in the caudate nucleus when DA (10−7 M) was directly introduced into the substantia nigra8. We present here a study of the effects of unilateral sensory stimulations on the release of DA from nerve terminals and dendrites of the two nigrostriatal dopaminergic pathways. Previous studies9 revealed an increase in the levels of homovanillic acid in the perfusates of the cat lateral ventricle during electrical stimulation of the paws.

What determines blood vessel structure? Genetic prespecification vs. hemodynamics.

Abstract: Vascular network remodeling, angiogenesis, and arteriogenesis play an important role in the pathophysiology of ischemic cardiovascular diseases and cancer. Based on recent studies of vascular network development in the embryo, several novel aspects to angiogenesis have been identified as crucial to generate a functional vascular network. These aspects include specification of arterial and venous identity in vessels and network patterning. In early embryogenesis, vessel identity and positioning are genetically hardwired and involve neural guidance genes expressed in the vascular system. We demonstrated that, during later stages of embryogenesis, blood flow plays a crucial role in regulating vessel identity and network remodeling. The flow-evoked remodeling process is dynamic and involves a high degree of vessel plasticity. The open question in the field is how genetically predetermined processes in vessel identity and patterning balance with the contribution of blood flow in shaping a functional vascular architecture. Although blood flow is essential, it remains unclear to what extent flow is able to act on the developing cardiovascular system. There is significant evidence that mechanical forces created by flowing blood are biologically active within the embryo and that the level of mechanical forces and the type of flow patterns present in the embryo are able to affect gene expression. Here, we highlight the pivotal role for blood flow and physical forces in shaping the cardiovascular system.

Progesterone stimulates the activity of the promoters of peripheral myelin protein-22 and protein zero genes in Schwann cells.

Abstract: To understand better the mechanisms by which progesterone (PROG) promotes myelination in the PNS, cultured rat Schwann cells were transiently transfected with reporter constructs in which luciferase expression was controlled by the promoter region of either the peripheral myelin protein-22 (PMP22) or the protein zero (P0) genes. PROG stimulated the P0 promoter and promoter 1, but not promoter 2, of PMP22. The effect of PROG was specific, as estradiol and testosterone only weakly activated promoters. Dose-response curves for stimulation of both promoter constructs by PROG were biphasic. RU486, a PROG antagonist, did not abolish the effect of PROG, but stimulated promoter activities by itself. In the human carcinoma cell line T47D expressing high levels of PROG receptor, PROG did not stimulate the P0 and PMP22 promoters, whereas the promoter region of the mouse mammary tumor virus was fully activated. Thus, the activation by PROG of promoter activity of two peripheral myelin protein genes is Schwann-cell specific.