Spectrum of neural electrical activity in guinea pig cochlea: effects of anaesthesia regimen, body temperature and ambient noise.

International audienceSpectral analysis of electric noise recorded from the round window of the cochlea is thought to represent the summed spontaneous activity of the auditory nerve. It has been postulated that it could provide a possible tinnitus index. Because experimental conditions could change this neural activity, the effect of anaesthesia regimen, body temperature and ambient noise on the spectrum of spontaneous neural noise (SNN) were investigated in guinea pig cochlea. SNN was studied in awake guinea pigs and after anaesthesia with pentobarbital (P), xylazine/ketamine (XK) or xylazine/tiletamine-zolazepam (XTZ). Body temperature varied gradually from 33 to 41 degrees C under XK regimen. In awake animals, broadband noise was generated with intensity varying from 0 to 50 dB. The SNN consisted in a broad peak at approximately 900 Hz. With ambient broadband noise, it increased exponentially with the sound level with no shift in frequency. Soon after anaesthetic induction, the lowest frequencies were constantly decreased, and gradually the 900 Hz peak either increased moderately (P) or dropped steeply (XTZ) or remained unchanged (XK). Peak frequency increased linearly with body temperature whereas the amplitude reached a maximum at around 39.5 degrees C. In conclusion, these data indicate that experimental conditions such as anaesthesia regimen, body temperature and ambient noise modify the spontaneous neural outflow of the cochlea and must be taken into account when studying SNN

Therapeutic efficacy of intra-cochlear administration of methylprednisolone after acoustic trauma caused by gunshot noise in guinea pigs.

International audienceThe therapeutic efficacy of cochlear infusion of methylprednisolone (MP) after an impulse noise trauma (170dB SPL peak) was evaluated in guinea pigs. The compound action potential threshold shifts were measured over a 14 days recovery period after the gunshot exposure. For each animal, one of the cochlea was perfused directly into the scala tympani with MP during 7 days via a mini-osmotic pump, whereas the other cochlea was not pump-implanted. The functional study of hearing was supplemented by histological analysis. Forty eight hours after the trauma, significant differences between auditory threshold shifts in the implanted and non-implanted ears were observed for frequencies above 8kHz. At day 7, the difference was significant for only one frequency and no difference was observed after 14 days recovery. Cochleograms showed that the hair cell losses were significantly lower in the MP treated ears. This work indicates that direct infusion of MP into perilymphatic space accelerates hearing recovery, reduces hair cell losses after impulse noise trauma but does not limit permanent threshold shifts

Influence of biomaterial and mesenchymal stem cell delivery on macrophage phenotype in the early inflammatory process after bone defect in rats

International audienc

Influence of biomaterial and mesenchymal stem cell delivery on macrophage phenotype in the early inflammatory process after bone defect in rats

International audienc

Pramoedya Ananta Toer and China: The Transformation of a Cultural Intellectual

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Histological analysis of liver, kidney and ileum damages in 12 Gy-irradiated rats with hind limbs or head protection 64 days post-irradiation.

<p>A: Representative pictures of liver sections stained with HES for control rats and 12 Gy-irradiated rats with either hind limbs or head protection. (V: Vessel, DHR: Disorganised Hepatocyte Rows, bHe: ballooned Hepatocytes). Control and irradiated rats were treated with Enrofloxacin. B: Representative pictures of kidney sections stained with HES for control rats and 12 Gy-irradiated rats with either hind limbs or head protection. (G: Glomerulus, DG: Dysmorphic Glomerulus, PT: Proximal Tubule, DT: Distal Tubule). Control and irradiated rats were treated with Enrofloxacin. C: Representative pictures of ileum sections stained with HES for control rats and 12 Gy-irradiated rats with either hind limbs or head protection. (Vi: Villus, C: Chorion, Cr: Crypt, MM: Muscular Mucosa). Control and irradiated rats were treated with Enrofloxacin. D: Measurements of villus length/width and villus number/mm performed using ileum HES staining images. Data on left and middle graphs represent the average of 12 measurements (from 3 rats in each condition). Analysis was performed from 3 control rats, 3 control rats treated with Enrofloxacin, 3 hind limbs-protected and 3 head-protected rats irradiated at 12 Gy. Both groups of 12 Gy-Irradiated rats received Enrofloxacin treatment. (*** (p<0.001); * (p<0.05); n.s.: not significant).</p

Histological scores of severity obtained for liver, kidney and ileum in control and 12 Gy-irradiated rats with hind limbs or head protection 64 days post-irradiation.

<p>A: Bar chart showing cumulative histological scores for liver in control (treated or not with Enrofloxacin) and 12 Gy-irradiated rats with hind limbs or head protection (treated with Enrofloxacin). B: Bar chart showing cumulative histological scores for kidney in control (treated or not with Enrofloxacin) and 12 Gy-irradiated rats with hind limbs or head protection (treated with Enrofloxacin). C: Bar chart showing cumulative histological scores for kidney in control (treated or not with Enrofloxacin) and 12 Gy-irradiated rats with hind limbs or head protection (treated with Enrofloxacin). Data were obtained from 3 controls, 3 controls treated with Enrofloxacin, 3 hind limbs-protected rats irradiated at 12 Gy and 3 head-protected rats irradiated at 12 Gy. (*** (p<0.001); ** (p<0.01); * (p<0.05); n.s.: not significant).</p

Kinetic analysis of plasma haptoglobin and corticosterone levels in 12 Gy-irradiated rats with hind limbs or head protection.

<p>A: Plasma haptoglobin level was measured using a Hitachi 912 automatic analyser. For each day post-irradiation (1, 4, 10, 21, 31, 37, 50, 59, 71, 101), data represent average values obtained from the plasma of 4–5 hind limbs-protected rats, 4–5 head-protected rats and 5 age-matched control rats from the same batch. All animals were treated with Enrofloxacin. Insert shows average values of haptoglobin plasma levels obtained by pooling data from 10 to 101 days post-irradiation. The number of rats used is indicated on the bar chart. B: Plasma corticosterone levels were measured using enzyme immunoassays (EIA) kits. For each day post-irradiation (1, 4, 10, 21, 31, 37, 50, 59, 71, 101), data represent average values obtained from the plasma of hind limbs-protected rats, head-protected rats and age-matched control rats from the same batch. All animals were treated with Enrofloxacin. (*** (p<0.001); ** (p<0.01); * (p<0.05); n.s.: not significant).</p

Histological scores of severity for kidneys collected 64 days after irradiation from 12 Gy-irradiated rats with hind limbs or head protection treated with Enrofloxacin and control rats treated or not with Enrofloxacin.

<p><i>Rat Groups</i>: <i>C</i>: Control; <i>C + E</i>: Control + Enrofloxacin; <i>12 Gy HL-p + E</i>: 12 Gy Hind limbs-protected + Enrofloxacin; <i>12 Gy H-p + E</i>: 12 Gy Head-protected + Enrofloxacin. For each parameter and for each rat group, values represent the average of scores obtained in three animals. Global histological scores represent average values (± SEM) of cumulated histological scores obtained from three rats for each group</p><p>** (p<0.01);</p><p>*** (p<0.001): significant versus control + Enrofloxacin;</p><p>§§ (p<0.01): significant versus 12 Gy Hind limbs-protected + Enrofloxacin).</p><p>Histological scores of severity for kidneys collected 64 days after irradiation from 12 Gy-irradiated rats with hind limbs or head protection treated with Enrofloxacin and control rats treated or not with Enrofloxacin.</p

Kinetic analysis of plasma CXCL1 levels in 12 Gy-irradiated rats with hind limbs or head protection.

<p>A: Plasma CXCL1 levels were measured by ELISA. For each day post-irradiation (1, 4, 10, 21, 31, 37, 50, 59, 64, 71), data represent average values obtained from the plasma of 3–5 hind limbs-protected rats, 3–5 head-protected rats and 3–5 age-matched control rats from the same batch. Data from Day 64 correspond to the animals used for histology analysis. All animals were treated with Enrofloxacin. B: Average values of CXCL1 plasma levels obtained by pooling data from several days after irradiation for controls and irradiated rats with hind limbs or head protection (left panel: from 21 to 71 days post-irradiation; right panel: from 50 to 64 days post-irradiation). The number of rats used is indicated on bar charts. (** (p<0.01); * (p<0.05); n.s.: not significant).</p