Yuliia V. Martynova

Background: The ability to measure drinking behaviour in laboratory animals is fundamental for neuroscience and metabolic research. In particular, the analysis of lick microstructure is an important tool for studying ingestive behaviour, motivation, and food preference. To capture lick microstructure, sensors capable of detecting licks in animals with a time resolution of only a few milliseconds are required. Methods: We designed a lick sensor that can be used with standard drinking bottles and does not require modifications to animal cages. It can be used in any experimental arena and with one or more drinking bottles simultaneously. Moreover, this lickometer reports lick events in real time and is thus suitable for driving additional laboratory hardware for real-time loop-control experiments. Our design is publicly available. Results: To validate our lick sensor we measured licks in mice offered water or sucrose drinks. Our sensor captured the same features of licking behaviour that have been reported before for these conditions using alternative lick sensors. Conclusions: The lick sensor described here is reliable while being easy to build and less expensive than known alternatives. It also facilitates the integration of lick measurements with other laboratory instruments in real time. This sensor lowers the barrier to implementing lick-sensing instrumentation in the laboratory which will be of benefit for research in neuroscience and metabolism.

The obesity epidemic is principally driven by the consumption of more calories than the body requires. It is therefore essential that the mechanisms underpinning feeding behavior are defined. The brainstem nucleus of the solitary tract (NTS) receives direct information from the digestive system and projects to second order regions in the brain. Though γ-Aminobutyric acid is widely expressed in the NTS (GABA ^NTS ), its function has not been defined. Characterization of GABA cells using single nucleus RNA sequencing (Nuc-Seq) identified at least 19 clusters. Here we provide insight into the function of GABA ^NTS cells, revealing that selective activation of GABA ^NTS neurons significantly controls food intake and body weight. Optogenetic interrogation of GABA ^NTS circuitry identified GABA ^NTS →arcuate nucleus of the hypothalamus (ARC) projections as appetite suppressive without creating aversion. Electrophysiological analysis revealed GABA ^NTS →ARC stimulation inhibits hunger promoting agouti-related protein/neuropeptide Y (AgRP/NPY) neurons via GABA release. Adopting an intersectional genetics strategy, we clarify that the GABA ^NTS →ARC circuit induces satiety. These data identify GABA ^NTS as a new modulator of feeding behavior, body weight and controller of orexigenic AgRP/NPY activity, thereby providing insight into the neural underpinnings of obesity. Highlights: Nucleus of the solitary tract (NTS) GABA neurons are responsive to nutritional status. Chemogenetic GABA ^NTS neuron activation reduces food intake and body weight. GABA ^NTS projections to the hypothalamic arcuate nucleus (ARC) promote satiety. Optogenetic GABA ^NTS →ARC stimulation inhibits orexigenic AgRP/NPY neurons. In Brief: Martinez de Morentin et al. identify GABAergic neurons in the nucleus of the solitary tract as a new player in the circuit governing feeding behavior and body weight.

Influence of Rhythmic Extreme Cooling (–120°С) on Functional State of Body in Rats in Their Aging

Probl Cryobiol Cryomed 2016; 26(2):159.

The application of the cryopreserved preparation of UCB NCs was accompanied by an enhanced activity of all the neurohumoral regulation elements of heart rate, although the absolute indices in 18- and 24-month-old animals did not reach similar ones in younger age groups. Also we noted an increase of thyroid hormone content in blood serum of aged rats, the level of which decreased with age. In addition, there was shown that the introduction of UCB NCs during animal life cycle (every 6 months) allowed keeping a functional state of the autonomic nervous system at a «young» physiological level.