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Valery Grinevich"Molecular anatomy of hypothalamic circuits"

Abstract :

The hypothalamus is an evolutionarily ancient brain structure, which controls endocrine, homeostatic and autonomic functions.
Although hypothalamic anatomy has been extensively studied during the 70’s-90’s of the last century, the intra- and extrahypothalamic connectivity of hypothalamic neurons and - as a consequence - the actions of hypothalamic neuropeptides within the brain are poorly understood and require new methodological approaches. We developed a technique to target oxytocin and vasopressin hypothalamic neurons in live rodents via recombinant adeno-associated virus (rAAV), carrying short evolutionarily conserved sequences of the respective promoters. The use of these rAAVs in combination with pseudotyped rabies virus (PRV) allowed us to identify new monosynaptic pathways within the hypothalamus as well as direct connections between magnocellular hypothalamic neurons and forebrain structures in the rat. Furthermore, we showed that the cell-type specific rAAVs are optimal for delivering various genes of interests into magnocellular hypothalamic neurons. However, the limitation of size of the promoters in rAAVs does not allow universally to apply these viruses for all cell populations residing in the hypothalamus. To overcome this obstacle, we employ the BAC technology to introduce full-length promoters for cell type specific targeting of other types of hypothalamic neurons, such as CRH and GnRH neurons. In conjunction with rAAVs, transgenic BAC mice provide an additional tool to study the connectivity of hypothalamic neurons. Despite the versatility of virus-based and transgenic approaches, these techniques seem to be not sufficient for evaluating dynamic changes in the activity of hypothalamic neurons. To fill in this gap, we recruit transgenic mice carrying promoters of immediate early genes. Starting from the recently generated BAC mouse, expressing a destabilized form of GFP under the control of Arc/Arg3.1 gene promoter, we identified the activation of new distinct subpopulations of hypothalamic neurons, encouraging us to study their connectivity in future. Taken together, the combinatory application of viral-based and transgenic techniques opens many perspectives to study hypothalamic circuits, monitor their activity during various physiological situations, and even screen the effects of neuropeptides on the activity of identified circuits. 

Selected publications

Liu, Y.; Coello, A. G.; Grinevich, V.; Aguilera, G.: Involvement of transducer of regulated CREB activity (TORC) in corticotropin releasing hormone transcription. Endocrinology (in press)
Grinevich, V.; Kolleker, A.; Eliava, M.; Takada, N.; Takuma, H.; Fukuzawa, Y.; Shigemoto, R.; Kuhl, D.; Waters, D. J.; Seeburg, P. H.; Osten, P.: Fluorescent Arc/Arg3.1 indicator mice: a versatile tool to study brain activity changes in vitro and in vivo. J. Neurosci. Methods (in press)
Sivukhina, E. V.; Poskrebysheva, A. S.; Smurova, Iu. V.; Dolzhikov, A. A.; Morozov, Iu. E.; Jirikowski, G. F.; Grinevich, V.: Altered Hypothalamic-Pituitary-Adrenal Axis Activity in Patients with Chronic Heart Failure . Horm. Metab. Res. , 2009 (ePub ahead of print)(online published)

Dionysia Théodosis