PubMed · 12266341
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P Audra, D Dargent. [Laparoscopic sterilization under local anesthesia].. https://pubmed.ncbi.nlm.nih.gov/12266341/
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RATIONALE AND OBJECTIVES: Blood oxygen level dependent (BOLD) contrast pharmacological magnetic resonance imaging (phMRI) is an increasingly popular technique that allows the non-invasive investigation of spatial and temporal changes in rat brain function in response to pharmacological stimulation in vivo. Rat brain BOLD contrast phMRI is, at present, established in few neuropharmacological laboratories, and various issues associated with the technique require attention. The present review is primarily aimed at psychopharmacologists with no previous experience of phMRI, who are interested in the practical aspects that phMRI studies entail. RESULTS AND DISCUSSION: Experimental and analytical considerations, including anaesthesia, physiological monitoring, drug dose and delivery, scanning protocols, statistical approaches and the interpretation of phMRI data, are discussed.
Cerebral blood flow is strictly regulated during hypoxic stress. Because of the preponderant role of the brainstem in cardiorespiratory controls, blood flow response to hypoxia is stronger in this region than in the cortex. However, the brainstem is made up of various regions which differ in their responsiveness to chemical stimuli. The objective of this study was to evaluate the distribution of blood flow during hypoxia using microsphere deposition methods in three brainstem regions containing key structures in cardiorespiratory controls: the nucleus tractus solitarus (NTS), the ventral respiratory groups (VRG) and the pontine respiratory groups (PRG). Microsphere injections were made during normoxia (FIO2=0.21) and after 15 min of hypoxia (FIO2=0.21). Based on this index, blood flow increase during hypoxia was higher in the VRG than in the dorsal part of the brainstem, containing the NTS and the PRG (P=0.002, n=10). These results suggest that blood flow response to hypoxia favours O(2) delivery in brainstem regions involved in respiratory rhythm generation.
In the present study we used the expression of the c-Fos-like protein as a "functional marker" to map populations of brainstem neurons involved in the generation of mastication. Experiments were conducted on urethane-anesthetized and paralyzed rabbits. In five animals (experimental group), rhythmical bouts of fictive masticatory-like motoneuron activity (cumulative duration 60-130 min) were induced by electrical stimulation of the left cortical "masticatory area" and recorded from the right digastric motoneuron pool. A control group of five animals (non-masticatory) were treated in the same way as the experimental animals with regard to surgical procedures, anesthesia, paralysis, and survival time. To detect the c-Fos-like protein, the animals were perfused, and the brainstems were cryosectioned and processed immunocytochemically. In the experimental group, the number of c-Fos-like immunoreactive neurons increased significantly in several brainstem areas. In rostral and lateral areas, increments occurred bilaterally in the borderzones surrounding the trigeminal motor nucleus (Regio h); the rostrodorsomedial half of the trigeminal main sensory nucleus; subnucleus oralis-gamma of the spinal trigeminal tract; nuclei reticularis parvocellularis pars alpha and nucleus reticularis pontis caudalis (RPc) pars alpha. Further caudally-enhanced labeling occurred bilaterally in nucleus reticularis parvocellularis and nucleus reticularis gigantocellularis (Rgc) including its pars-alpha. Our results provide a detailed anatomical record of neuronal populations that are correlated with the generation of the masticatory motor behavior.