MRS glucose mapping and PET joining forces: re‐evaluation of the lumped constant in the rat brain under isoflurane anaesthesia

Abstract

Although numerous positron emission tomography (PET) studies with 18 F-fluoro-deoxyglucose (FDG) have reported quantitative results on cerebral glucose kinetics and consumption, there is a large variation between the absolute values found in the literature. One of the underlying causes is the inconsistent use of the lumped constants (LCs), the derivation of which is often based on multiple assumptions that render absolute numbers imprecise and errors hard to quantify. We combined a kinetic FDG-PET study with magnetic resonance spectroscopic imaging (MRSI) of glucose dynamics in Sprague-Dawley rats to obtain a more comprehensive view of brain glucose kinetics and determine a reliable value for the LC under isoflurane anaesthesia. Maps of T max /CMR glc derived from MRSI data and T max determined from PET kinetic modelling allowed to obtain an LC-independent CMR glc . The LC was estimated to range from 0.33 AE 0.07 in retrosplenial cortex to 0.44 AE 0.05 in hippocampus, yielding CMR glc between 62 AE 14 and 54 AE 11 lmol/min/100 g, respectively. These newly determined LCs for four distinct areas in the rat brain under isoflurane anaesthesia provide means of comparing the growing amount of FDG-PET data available from translational studies.

Visible, Safe and Certain Endotracheal Intubation Using Endoscope System and Inhalation Anesthesia for Rats

“…However, we also observed some points that could be more practically improved. Although rats rank second only to mice in number used in biomedical research and share many of the research purposes and the attributes of mice, they are commonly used in research fields, such as an organ transplantation [14, 16, 22, 23, 33], regenerative medicine [22, 23, 33] and imaging [1, 2, 25, 28], because rats’ body size is larger than that of mice. Therefore, in this experiment, we investigated both the effectiveness of endotracheal intubation in rats using endoscopic technology and improvements of inhalation anesthesia using isoflurane for rats.…”

“…Room air was used as a carrier gas, and the ventilator was set as follows: 250 ± 10 m l flow volume/min for male and 190 ± 10 m l flow volume/min for female, 70 breaths/min and 50% I/I + E (I: intake, E: exhaust). Airway pressure in the anesthetic circuit was continuously monitored, and the alarm was set to sound when the pressure exceeded 1,600 pa [2, 7, 13, 21, 31]. Vital signs were continuously measured and recorded using the MouseOx Plus® (Starr Life Sciences Corp. Pittsburgh, PA, U.S.A.).…”

“…Rats and mice, used for laboratory experiments, together form more than 90% of all mammalian species, and rats rank second only to mice in number used in biomedical research including imaging [1, 2, 25, 28] and long-time surgery [14, 16, 22, 33]. …”

Methods for quantification of cerebral glycolytic metabolism using 2-deoxy-2-[18 F]fluoroglucose in small animals

“…However, under conditions that include factors that alter plasma glucose concentration and consequently result in changes of greater or lesser magnitude in LC, LC should be determined for the specific conditions of the study. Several studies have shown changes in LC in hyperglycaemic (Orzi et al, 1988;Schuier et al, 1990), hypoglycaemic (Suda et al, 1990) and anaesthetized (Alf et al, 2014) animals, or in animals with tumours (Spence et al, 1998).…”

A new video laryngoscope specialized for endotracheal intubation in mice

“…Small rodents such as rats and mice are used in more than 90% of mammalian experiments in biomedical studies. In many animal experiments that involve imaging [1][2][3][4]and long-term surgery [5][6][7][8][9], mechanical ventilation is needed to assist breathing. Establishing a stable airway to control breathing is the prerequisite.…”