Acute nicotine intake increases feeding behavior through decreasing glucagon signaling in dependent male and female rats.

Chronic use of nicotine is known to dysregulate metabolic signaling through altering circulating levels of feeding-related hormones, contributing to the onset of disorders like type 2 diabetes. However, little is known about the acute effects of nicotine on hormonal signaling. We previously identified an acute increase in food intake following acute nicotine, and we sought to determine whether this behavior was due to a change in hormone levels. We first identified that acute nicotine injection produces an increase in feeding behavior in dependent rats, but not nondependent rats. We confirmed that chronic nicotine use increases circulating levels of insulin, leptin, and ghrelin, and these correlate with rats' body weight and food intake. Acute nicotine injection in dependent animals decreased circulating GLP-1 and glucagon levels, and administration of glucagon prior to acute nicotine injection prevented the acute increase in feeding behavior. Thus, acute nicotine injection increases feeding behavior in dependent rats by decreasing glucagon signaling.

High quality, high throughput, and low-cost simultaneous video recording of 60 animals in operant chambers using PiRATeMC.

Background: The development of Raspberry Pi-based recording devices for video analyses of drug self-administration studies has shown to be promising in terms of affordability, customizability, and capacity to extract in-depth behavioral patterns. Yet, most video recording systems are limited to a few cameras making them incompatible with large-scale studies. New Method: We expanded the PiRATeMC (Pi-based Remote Acquisition Technology for Motion Capture) recording system by increasing its scale, modifying its code, and adding equipment to accommodate large-scale video acquisition, accompanied by data on the throughput capabilities, video fidelity, synchronicity of devices, and comparisons between the Raspberry Pi 3B+ and 4B models. Results: Using PiRATeMC default recording parameters resulted in minimal storage (~350MB/h), high throughput (< ~120 seconds/Pi), high video fidelity, and synchronicity within ~0.02 seconds, affording the ability to simultaneously record 60 animals in individual self-administration chambers at a fraction of current commercial costs. No consequential differences were found between Raspberry Pi 3B+ and 4B models. Comparison with Existing Methods: This system allows greater acquisition of video data simultaneously than other video recording systems by an order of magnitude with less storage needs and lower costs. Additionally, we report in-depth quantitative assessments of throughput, fidelity, and synchronicity, displaying real-time system capabilities. Conclusions: The system presented is able to be fully installed in a month's time by a single technician and provides a scalable, low cost, and quality-assured procedure with a high-degree of customization and synchronicity between recording devices, capable of recording a large number of subjects with high turnover in a variety of species and settings.