LPLRFamide exerts short-term anorexigenic effects that coincide with magnocellular division of the hypothalamic paraventricular nucleus activation.

LPLRFamide is a member of the RFamide peptide family that elicits an anorexigenic effect when centrally injected in chicks although the mechanism mediating this response is poorly understood. Therefore, the purpose of this experiment was to elucidate the hypothalamic mechanism of short-term anorexia after central administration of LPLRFamide in chicks. In Experiment 1 chicks centrally injected with LPLRFamide decreased food intake at 15min but not 30min following administration compared to vehicle-injected chicks. For Experiment 2, c-Fos immunoreactivity was quantified in several appetite-associated hypothalamic nuclei and in LPLRF-injected chicks, compared to vehicle-injected chicks, there was an increase in the number of reactive cells in the magnocellular division of the paraventricular nucleus. Lastly in Experiment 3, real time-PCR was performed and hypothalamic proopiomelanocortin (POMC) mRNA abundance was increased in LPRLFamide-injected chicks compared to vehicle-injected chicks. Thus, following central injection of LPLRFamide there is activation of the paraventricular nucleus of the hypothalamus and increased expression of hypothalamic POMC mRNA in chicks.

An immersive first-person navigation task for abstract knowledge acquisition.

Advances in virtual reality (VR) technology have greatly benefited spatial navigation research. By presenting space in a controlled manner, changing aspects of the environment one at a time or manipulating the gain from different sensory inputs, the mechanisms underlying spatial behaviour can be investigated. In parallel, a growing body of evidence suggests that the processes involved in spatial navigation extend to non-spatial domains. Here, we leverage VR technology advances to test whether participants can navigate abstract knowledge. We designed a two-dimensional quantity space-presented using a head-mounted display-to test if participants can navigate abstract knowledge using a first-person perspective navigation paradigm. To investigate the effect of physical movement, we divided participants into two groups: one walking and rotating on a motion platform, the other group using a gamepad to move through the abstract space. We found that both groups learned to navigate using a first-person perspective and formed accurate representations of the abstract space. Interestingly, navigation in the quantity space resembled behavioural patterns observed in navigation studies using environments with natural visuospatial cues. Notably, both groups demonstrated similar patterns of learning. Taken together, these results imply that both self-movement and remote exploration can be used to learn the relational mapping between abstract stimuli.

The anorexigenic effect of neuropeptide K in chicks involves the paraventricular nucleus and arcuate nucleus of the hypothalamus.

Neuropeptide K (NPK) induces satiety in birds and mammals. We demonstrated that in birds this effect was associated with the hypothalamus, but beyond this little is known in any species regarding the central mechanism of action. Thus, this study was designed to identify hypothalamic molecular mechanisms associated with the food intake-inhibiting effects of NPK in chicks. In Experiment 1, intracerebroventricular (ICV) injection of 1.0 and 3.0 nmol of NPK reduced food intake and we identified an effective dose for microinjection. In Experiment 2, food intake was reduced when NPK was microinjected into the PVN. In Experiment 3, whole hypothalamus was collected from chicks at 1 h post-ICV NPK injection. The abundance of corticotropin-releasing factor (CRF) and agouti-related peptide (AgRP) mRNA was reduced in NPK-injected chicks. In Experiment 4, within the isolated paraventricular nucleus (PVN) there was less CRF mRNA, and within the arcuate nucleus (ARC) there was less AgRP mRNA, in NPK- than vehicle-treated chicks at 1 h post-injection. We conclude that there are first order neurons for NPK that reside within the PVN, and the anorexigenic effect of NPK is associated with a decrease in AgRP in the ARC.