Search

Pharmacological MRI at 4.7 T was used to investigate the secretory response to Sylvestris pine oil stimuli in the rat airways, with the aim of developing an in vivo model in a small laboratory animal. The availability of such a model would greatly facilitate the drug discovery process using compounds active on airway surface liquid (ASL) production, and would make it possible to obtain information on chemoreceptoral mechanisms and to test the effects of environmental substances on the airways. T1- and T2-weighted images were acquired in the trachea and larynx before and at various times after exposure to pine oil. Several post-processing procedures were tested in order to improve the visibility of the secretory response and to measure the enhancement of the signal intensity of ASL. A semiautomatic application software was written to localize and to measure the volume involved in the secretory response to a compound administration. A significant effect of the pine oil administration on the secretory response was founded in trachea (p<0.01) and in the salivary glands (p<0.01). 3D reconstructions of MRI data and virtual endoscopy permitted a quick visualization of tracheal morphology and localization of the greatest response to stimulus. The study demonstrated that, despite technical problems due to the air/tissue interface and to the small dimensions of the experimental animals, the secretory response can be evaluated and the pharmacological MRI (phMRI) of the rat airways is feasible. The potential and the limitations of phMRI investigation in drug targeting of ASL are discussed.

The hydrolipidic ratio (HLR) expresses the amount of water and fat in a tissue. HLR can be studied non-invasively in the living organism and can be mapped in different areas of the body with high spatial and temporal resolution. In the present work we have evaluated the HLR in different adipose tissue depots in young or adult rats using tissue arrays of fat fragments by 1H-spectroscopy. In young animals, the highest percentage of water (33%) was found in the interscapular brown adipose tissue (iBAT). Mesenteric fat (mWAT) also appeared highly hydrated (24%). The deposits composed of epididymal, retroperitoneal and pelvic white adipose tissue (eWAT, rWAT and pWAT, respectively) contained an amount of water ranging from 14% to 17%. In adult animals, a reduction of the water content was found in all the depots. In e/r/pWAT, the age-related maturation was characterized by large changes in adipocyte diameter accompanied by a small change in HLR. In the iBAT, the maturation was accompanied by small change in adipocyte diameter and a greater diminution of HLR. mWAT showed an intermediate pattern between e/r/pWAT and iBAT. In all the studied depots, an age-related increase in leptin expression was found. This increase was relatively low in iBAT (40%) and high in the e/r/pWAT (204-273%). The work expand the knowledge about the physiological significance of the HLR by 1H-spectroscopy.

High field intensity magnetic resonance imaging (HF-MRI) has been applied to the in vivo study of age-related processes of organs located in the cervical-thoracic region in mice and to describe the effects of oral zinc supplementation on these processes. Spin-echo (SE) pulse sequence and chemical shift imaging (CSI) techniques have been used. Aging produced a progressive reduction of muscular masses and of thymic area, whereas the HF-MRI appearances of spinal cord and of salivary glands were unchanged. In some aged animals, subcutaneous fat was reduced while visceral fat was well developed. In the group of old animals supplemented with zinc sulphate, muscular masses were more developed than that of the group of untreated old animals. Oral zinc supplementation also produced an enlargement of the adipose tissue and the thymic area showed an increase of about 65% compared with thymic area measured in the group of old animals used as controls. The present study confirms previous data about the effects of Zn supplementation on aging processes and demonstrates that HF-MRI is a powerful technique to study processes of aging, providing information about the effects of drug treatments on these processes.