Effects of meperidine or saline on thermal, mechanical and electrical nociceptive thresholds in cats

Objective To measure cutaneous electrical nociceptive thresholds in relation to known thermal and mechanical stimulation for nociceptive threshold detection in cats.Study design Prospective, blinded, randomized cross-over study with 1-week washout interval.Animals Eight adult cats [bodyweight 5.1 +/- 1.8 kg (mean + SD)].Methods Mechanical nociceptive thresholds were tested using a step-wise manual inflation of a modified blood pressure bladder attached to the cat's thoracic limb. Thermal nociceptive thresholds were measured by increasing the temperature of a probe placed on the thorax. The electrical nociceptive threshold was tested using an escalating current from a constant current generator passed between electrodes placed on the thoracic region. A positive response (threshold) was recorded when cats displayed any or all of the following behaviors: leg shake, head turn, avoidance, or vocalization. Four baseline readings were performed before intramuscular injection of meperidine (5 mg kg(-1)) or an equal volume of saline. Threshold recordings with each modality were made at 15, 30, 45, 60, 90, and 120 minutes post-injection. Data were analyzed using ANOVA and paired t-tests (significance at p < 0.05).Results There were no significant changes in thermal, mechanical, or electrical thresholds after saline. Thermal thresholds increased at 15-60 minutes (p < 0.01) and mechanical threshold increased at 30 and 45 minutes after meperidine (p < 0.05). Maximum thermal threshold was +4.1 +/- 0.3 degrees C above baseline at 15 minutes while maximum mechanical threshold was 296 +/- 265 mmHg above baseline at 30 minutes after meperidine. Electrical thresholds following meperidine were not significantly different than baseline (p > 0.05). Thermal and electrical thresholds after meperidine were significantly higher than saline at 30 and 45 minutes (p < 0.05), and at 120 minutes (p < 0.05), respectively. Mechanical thresholds were significantly higher than saline treatment at 30 minutes (p <= 0.05).Conclusion and clinical relevance Electrical stimulation did not detect meperidine analgesia whereas both thermal and mechanical thresholds changed after meperidine administration in cats.

Effect of intravenous propofol and remifentanil on heart rate, blood pressure and nociceptive response in acepromazine premedicated dogs

ObjectiveTo investigate the cardiorespiratory, nociceptive and endocrine effects of the combination of propofol and remifentanil, in dogs sedated with acepromazine.Study designProspective randomized, blinded, cross-over experimental trial.AnimalsTwelve healthy adult female cross-breed dogs, mean weight 18.4 +/- 2.3 kg.MethodsDogs were sedated with intravenous (IV) acepromazine (0.05 mg kg-1) followed by induction of anesthesia with IV propofol (5 mg kg-1). Anesthesia was maintained with IV propofol (0.2 mg kg-1 minute-1) and remifentanil, infused as follows: R1, 0.125 mu g kg-1 minute-1; R2, 0.25 mu g kg-1 minute-1; and R3, 0.5 mu g kg-1 minute-1. The same dogs were administered each dose of remifentanil at 1-week intervals. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (f(R)), end tidal CO(2) (Pe'CO(2)), arterial hemoglobin O(2) saturation, blood gases, and rectal temperature were measured before induction, and 5, 15, 30, 45, 60, 75, 90, and 120 minutes after beginning the infusion. Nociceptive response was investigated by electrical stimulus (50 V, 5 Hz and 10 ms). Blood samples were collected for plasma cortisol measurements. Statistical analysis was performed by anova (p < 0.05).ResultsIn all treatments, HR decreased during anesthesia with increasing doses of remifentanil, and increased significantly immediately after the end of infusion. MAP remained stable during anesthesia (72-98 mmHg). Antinociception was proportional to the remifentanil infusion dose, and was considered satisfactory only with R2 and R3. Plasma cortisol concentration decreased during anesthesia in all treatments. Recovery was smooth and fast in all dogs.Conclusions and clinical relevanceInfusion of 0.25-0.5 mu g kg-1 minute-1 remifentanil combined with 0.2 mg kg-1 minute-1 propofol produced little effect on arterial blood pressure and led to a good recovery. The analgesia produced was sufficient to control the nociceptive response applied by electrical stimulation, suggesting that it may be appropriate for performing surgery.

Use of corticosteroid therapy on the modulation of uterine inflammatory response in mares after artificial insemination with frozen semen

In order to modulate uterine inflammatory response and evaluate the effect of corticosteroid therapy on fertility, 90 cycles of 45 mares were used for artificial insemination with frozen semen, using three different protocols: G1 - inseminated with frozen semen (800 x 10(6) viable spermatozoa pre-freezing) + 20 mL of seminal plasma; G2 - inseminated with frozen semen (800 x 10(6) viable spermatozoa pre-freezing) + corticosteroid therapy; G3 - inseminated with frozen semen (800 x 10(6) viable spermatozoa pre-freezing) + 20 mL of seminal plasma + corticosteroid therapy. Corticosteroid therapy consisted on one administration of prednisolone acetate (0.1 mg/Kg - Predef (R)) when mares presented 35mm follicles and uterine edema, concomitantly with the unique dose of hCG (human chorionic gonadotropin), then repeated each 12 hours until ovulation. on first fertility trial, with normal mares, there was no difference between control and treated groups (p>0.05), using seminal plasma associated with corticosteroid therapy (40 vs. 38%, respectively) or corticosteroid therapy alone (40 vs. 45% respectively). The second fertility trial, performed with mares with previous history of post-insemination endometritis, demonstrated a significant increase of pregnancy rate when mares were submitted to corticosteroid therapy (0.0 vs. 64.5%, respectively; p<0.05). Corticosteroid therapy was shown to be safe, with no physical or reproductive alterations on treated mares, demonstrating to be an adequate option to those animals with history of post-breeding or post-insemination endometritis. Further clinical research is necessary to confirm these results and contribute to the establishment of preventive therapy for cases of post-insemination endometritis.

Modulation of host cell signaling pathways as a therapeutic approach in periodontal disease

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Neurochemistry of the afferents to the rat cochlear root nucleus: Possible synaptic modulation of the acoustic startle

Afferents to the primary startle circuit are essential for the elicitation and modulation of the acoustic startle reflex (ASR). In the rat, cochlear root neurons (CRNs) comprise the first component of the acoustic startle circuit and play a crucial role in mediating the ASR. Nevertheless, the neurochemical pattern of their afferents remains unclear. To determine the distribution of excitatory and inhibitory inputs, we used confocal microscopy to analyze the immunostaining for vesicular glutamate and GABA transporter proteins (VGLUT1 and VGAT) on retrogradely labeled CRNs. We also used reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry to detect and localize specific neurotransmitter receptor subunits in the cochlear root. Our results show differential distributions of VGLUT1- and VGAT-immunoreactive endings around cell bodies and dendrites. The RT-PCR data showed a positive band for several ionotropic glutamate receptor subunits, M1-M5 muscarinic receptor subtypes, the glycine receptor alpha 1 subunit (GlyR alpha 1), GABA(A), GABA(B), and subunits of alpha 2 and beta-noradrenergic receptors. By immunohistochemistry, we confirmed that CRN cell bodies exhibit positive immunoreaction for the glutamate receptor (GluR) 3 and NR1 GluR subunits. Cell bodies and dendrites were also positive for M2 and M4, and GlyR alpha 1. Other subunits, such as GluR1 and GluR4 of the AMPA GluRs, were observed in glial cells neighboring unlabeled CRN cell bodies. We further confirmed the existence of nor-adrenergic afferents onto CRNs from the locus coeruleus by combining tyrosine hydroxylase immunohistochemistry and tract-tracing experiments. Our results provide valuable information toward understanding how CRNs might integrate excitatory and inhibitory inputs, and hence how they could elicit and modulate the ASR. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.

Down-modulation of lymphoproliferation and interferon-gamma production by beta-glucan derived from Saccharomyces cerevisiae

beta-glucan, one of the major cell wall components of Saccharomyces cerevisiae, has been found to enhance immune functions. This study investigated in vivo and in vitro effects of beta-glucan on lymphoproliferation and interferon-gamma (IFN-gamma) production by splenic cells from C57BL/6 female mice. All experiments were performed with particulate beta-glucan derived from S. cerevisiae. Data demonstrated that both, i.p administration of particulate beta-glucan (20 or 100 µg/animal) and in vitro stimulation of splenic cells (20 or 100 µg/ml of culture) decreased lymphoproliferation and IFN-gamma production induced by concanavalin A. These results suggest that beta-glucan can trigger a down-modulatory effect regulating a deleterious immune system hyperactivity in the presence of a strong stimulus.

Mouse ear edema modulation by different propolis ethanol extracts

The anti-inflammatory activity of 14 commercial ethanol extracts of propolis were evaluated, using a mouse ear inflammation model induced by arachidonic acid. Indometacin was also assayed as standard anti-inflammatory agent. Different activities were observed and discussed. This model could be used to assess the anti-inflammatory quality of propolis extracts and facilitate their posological usage on skin edema resulting from wounds.

Mechanisms of insulin secretion in malnutrition: modulation by amino acids in rodent models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modulation of smooth muscle cell function: Morphological evidence for a contractile to synthetic transition in the rat ventral prostate after castration

In this study, we evaluated the involvement of rat ventral prostate smooth muscle cells (SMC) in secretory activity and whether this function is modulated after castration. Cell morphology was examined at both light and electron microscopy levels and the organelles involved in secretory function were labeled by the zinc-iodide-osmium (ZIO) method at the ultrastructural level and their volume density was determined by stereology. Castration resulted in marked changes of the SMC, which adopted a spinous aspect and abandoned the layered arrangement observed in the prostates of non-castrated rats. The volume density of ZIO reactive organelles increased progressively after castration, reaching significantly higher levels 21 days after castration, Since previous studies have demonstrated that SMC express SMC markers (even 21 days after castration) and are able to respond to adrenergic stimulation, we concluded that differentiated SMC are able to shift from a predominantly contractile to a more synthetic phenotype without changing their differentiation status. (c) 2005 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.

An immunocytochemical and in situ hybridization analysis of annexin 1 expression in rat mast cells: Modulation by inflammation and dexamethasone

The presence and localization of the anti-inflammatory protein annexin 1 (also known as lipocortin 1) in perivenular rat mast cells was investigated here. Using the rat mesenteric microvascular bed and a combination of morphologic techniques ranging from immunofluorescence to electron microscopy analyses, we detected the presence of annexin 1 in discrete intracellular sites, both in the nucleus and in the cytoplasm. In resting mast cells, most of the protein pool (approximately 80% of the cytosolic portion) was localized to cytoplasmic granules. In agreement with other cell types, treatment of rats with dexamethasone (0.2 mg/kg, ip) increased annexin 1 expression in mast cells, inducing a remarkable appearance of dusters of protein immunoreactivity. This effect was most likely the result of de novo protein synthesis as determined by an increase in mRNA seen by in situ hybridization. Triggering an ongoing experimental inflammatory response (0.3 mg of carrageenin, ip) increased annexin 1 mRNA and protein levels. In conclusion, we report for the first time the localization of annexin 1 in connective tissue mast cells, and its susceptibility not only to glucocorticoid hormone treatment, but also to an experimental acute inflammatory response.

Effect of exogenous galectin-1 on leukocyte migration: modulation of cytokine levels and adhesion molecules

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)