Evaluation of the impact of shielding materials in radiation protection in transgenic animals

We are using a plasmid-based transgenic mouse mutation model system to evaluate the effectiveness of aluminum or low-density polyethylene (LDPE) shielding after 250 MeV/u protons or 1 GeV/u iron ion irradiation. Transgenic mice, with multiple copies of the plasmid pUR288 lacZ transgene integrated into the genome of every cell of the animal, were either irradiated or sham-treated. Multiple endpoints, including early cytogenetic damage in erythrocytes at 48 h after exposure, chromosome aberrations in bone marrow lymphocytes, and lacZ mutant frequencies (MF) in brain and spleen tissues were measured in the same animals. The frequency of total circulating reticulocytes (fRET) dropped precipitously at 48 h after 2 Gy of proton irradiation. The average level of micronucleated reticulocytes (fMN–RET) was fivefold higher in the irradiated samples relative to the controls at the same time point. There was an increase in total chromosome aberrations in bone marrow lymphocytes at 8 weeks after proton irradiation but this increase was not statistically significant relative to the controls. Evaluation of the lacZ MF in the brain and spleen tissues showed that proton irradiation induced a twofold increase in MF in each tissue. Similar samples were collected from animals that were shielded from the proton beam by aluminum. Compared to the unshielded treatment group, we noted no difference in fRET, fMN–RET, chromosome aberrations in lymphocytes and lacZ MF in brain and spleen tissues obtained from these animals. In a separate study, animals were exposed to high-energy iron ions with or without 10 or 15 cm LDPE. Using the same approach, we noted a precipitous drop in fRET, and an elevation in fMN–RET within 48 h after 1 Gy of iron ions. Total chromosome aberrations in bone marrow lymphocytes were slightly elevated but not significant at 8 weeks after iron ion exposure. Shielding animals with 10 or 15 cm of polyethylene appeared to have no effect on the level of RET, MN–RET or chromosome aberrations in these animals. LacZ MF in brain and spleen tissues increased 1.5–2-fold above control levels after 1 Gy iron ions at 8 weeks after treatment. On the other hand, MF in tissues harvested from shielded animals appeared to be lower than their unshielded litermates, suggesting the polyethylene shielding was effective in reducing the iron-induced genomic damage in tissues. Although shielding may be effective, in some cases, in reducing the physical dose of particle radiation, our cytogenetic results showed that the biological impact of the particle beam remain unchanged. On the other hand, reduction in transgene MF in tissues from LDPE-shielded animals but not in the aluminum-shielded animals strongly suggests that careful consideration of the biological endpoints used is necessary in the evaluation of the efficacy of the selected shielding material.     

The peripheral nerve allograft: a dose-response curve in the rat immunosuppressed with cyclosporin A

The potential use of peripheral nerve allografts would significantly improve the reconstructive potential for patients with major peripheral nerve deficits. This study evaluated the response of the nerve allograft recipient treated with varying dosages of cyclosporin A (CsA) to determine the minimal effective dosage necessary to prevent nerve graft rejection. Lewis rats (RT1l) were the recipients of syngeneic nerve grafts from identical Lewis donors or allogeneic nerve grafts from ACI (RT1a) donors. Nerve grafts were inlaid next to the intact sciatic nerve of the recipient. The immunologic responsiveness of the recipient animal's lymphocytes to a donor-specific antigenic challenge was assessed by the mixed lymphocyte reaction (MLR). In addition, nerve grafts were evaluated histologically. Animals were monitored for cyclosporin A toxicity. It was found that cyclosporin A (5 mg/kg per day) was effective in rendering the recipient animals unresponsive by mixed lymphocyte reaction at 10, 20, and 40 days after engraftment. This dosage was similarly effective in preventing histologic changes characteristic of nerve allograft rejection. This dosage regimen was nontoxic to the animals. Our study ascertained a minimal nontoxic dosage of cyclosporin A that effectively prevented nerve allograft rejection across a major histocompatibility disparity in rats.     

Effect of intracerebral implantation of the embryonicLocus Coeruleus on the conditioned reflex avoidance reaction in rats with experimental atrophy of the frontotemporal brain cortex

We studied the effect of intracerebral grafting of the embryoniclocus coeruleus from donor rats on the conditioned reflex emotional avoidance reaction (EAR) and contents of adrenaline and noradrenaline in the brain structures and body tissues of recipient rats. Group 1 of the animals consisted of intact rats, group 2 included rats with electrolytic impairment and subsequent atrophy of the frontotemporal brain cortex regions, while in group 3 the rats with impaired cortex were subjected to parallel transplantation of the embryoniclocus coeruleus into the injured region. Group-3 animals manifested a considerable level of recovery of the conditioned reflex behavioral stereotype disturbed after the cortical injury. Biochemical analysis showed that transplantation of the embryoniclocus coeruleus exerts a rehabilitative/regulating influence on the functioning of the catecholaminergic systems in the group-3 rats.     

Effect of weak combined static and extremely low-frequency alternating magnetic fields on spatial memory and brain amyloid-β in two animal models of Alzheimer’s disease

Subchronic effect of a weak combined magnetic field (MF), produced by superimposing a constant component, 42 µT and an alternating MF of 0.08 µT, which was the sum of two frequencies of 4.38 and 4.88 Hz, was studied in olfactory bulbectomized (OBE) and transgenic Tg (APPswe, PSEN1) mice, which were used as animal models of sporadic and heritable Alzheimer’s disease (AD) accordingly. Spatial memory was tested in a Morris water maze on the following day after completion of training trials with the hidden platform removed. The amyloid-β (Aβ) level was determined in extracts of the cortex and hippocampus of mice using a specific DOT analysis while the number and dimensions of amyloid plaques were detected after their staining with thioflavin S in transgenic animals. Exposure to the MFs (4 h/day for 10 days) induced the decrease of Aβ level in brain of OBE mice and reduced the number of Aβ plaques in the cortex and hippocampus of Tg animals. However, memory improvement was revealed in Tg mice only, but not in the OBE animals. Here, we suggest that in order to prevent the Aβ accumulation, MFs could be used at early stage of neuronal degeneration in case of AD and other diseases with amyloid protein deposition in other tissues.     

Neuronal and Glial Expression of the Multidrug Resistance Gene Product in an Experimental Epilepsy Model

1. Failure of anticonvulsive drugs to prevent seizures is a common complication of epilepsy treatment known as drug-refractory epilepsy but their causes are not well understood. It is hypothesized that the multidrug resistance P-glycoprotein (Pgp-170), the product of the MDR-1 gene that is normally expressed in several excretory tissues including the blood brain barrier, may be participating in the refractory epilepsy. 2. Using two monoclonal antibodies against Pgp-170, we investigated the expression and cellular distribution of this protein in the rat brain during experimentally induced epilepsy. Repeated seizures were induced in male Wistar rats by daily administration of 3-mercaptopropionic acid (MP) 45 mg/kg i.p. for either 4 days (MP-4) or 7 days (MP-7). Control rats received an equivalent volume of vehicle. One day after the last injection, rats were sacrificed and brains were processed for immunohistochemistry for Pgp-170. As it was previously described, Pgp-170 immunostaining was observed in some brain capillary endothelial cells of animals from control group. 3. Increased Pgp-170 immunoreactivity was detected in MP-treated animals. Besides the Pgp-170 expressed in blood vessels, neuronal, and glial immunostaining was detected in hippocampus, striatum, and cerebral cortex of MP-treated rats. Pgp-170 immunolabeled neurons and glial cells were observed in a nonhomogeneous distribution. MP-4 animals presented a very prominent Pgp-170 immunostaining in the capillary endothelium, surrounding astrocytes and some neighboring neurons while MP-7 group showed increased neuronal labeling. 4. Our results demonstrate a selective increase in Pgp-170 immunoreactivity in the brain capillary endothelial cells, astrocytes, and neurons during repetitive MP-induced seizures. 5. The role for this Pgp-170 overexpression in endothelium and astrocytes as a clearance mechanism in the refractory epilepsy, and the consequences of neuronal Pgp-170 expression remain to be disclosed.     

Increased vascular permeability in the circumventricular organs of adult rat brain due to stimulation by extremely low frequency magnetic fields

It has been demonstrated that the exposure of biological systems to magnetic fields (MFs) can produce several beneficial effects: tissue recovery in chronic wounds, re‐establishment of blood circulation after tissue ischemia or in necrotic tissues, improvement after epileptic episodes, angiogenesis, etc. In the current study, the effects of extremely low frequency (ELF) MF on the capillaries of some circumventricular organs (CVOs) are demonstrated; a vasodilator effect is reported as well as an increase in their permeability to non‐liposoluble substances. For this study, 96 Wistar male rats (250 g body mass) were used and divided into three groups of 32 rats each: a control group (no treatment); a sham ELF‐MF group; and an experimental group subjected to ELF‐MF (120 Hz harmonic waves and 0.66 mT, root mean square) by the use of Helmholtz coils. All animals were administered colloidal carbon (CC) intravenously to study, through optical and transmission electron microscopy, the capillary permeability in CVOs and the blood–brain barrier (BBB) in brain areas. An increase in capillary permeability to CC was detected in the ELF‐MF‐exposed group as well as a significant increase in vascular area (capillary vasodilation); none of these effects were observed in individuals of the control and sham ELF‐MF groups. It is important to investigate the mechanisms involved in the phenomena reported here in order to explain the effects of ELF‐MF on brain vasculature. Bioelectromagnetics 34:145–155, 2013. © 2012 Wiley Periodicals, Inc.     

Antinociceptive Effects in Normal and Diabetic Rats Exposed to 50?Hz Magnetic Field

The effects of repeated applications of alternating sinusoidal 50 Hz magnetic field, MF (B = 5.0 mT, 165-minlong sessions everyday, each including four 30-min-long exposures separated by 15-min-long intervals, carried out for 30 days), on thermonociception (estimated using the tail-flick test) were examined in intact rats, diabetic rats (induction by streptozotocin), and diabetic rats treated with insulin. Exposures to MF led to mild (several percent) increases in the tail-flick latency, TFL, immediately after each session and a sustained rather significant rise in this parameter (increment up to 40 %) developing with some delay, from 2 to 4 days. The latter effect was limited in time (lasting 2 days long); then, the TFLs tended to rapidly return to initial (or nearly initial) values. This intense hypoalgesic effect induced by MF exposures was observed on days 3 and 4 in normal rats, on days 4 and 5 in diabetic rats, and on days 5 and 6 in diabetic rats treated with insulin. Significant increases in the mean arterial blood pressure were observed in diabetic rats; exposures to MF exerted no significant influence on this parameter in both normal and diabetic animals. Mechanisms of the development of diabetic neuropathy and those of the hypoalgesic actions of MF are discussed. The MF-induced antinociception seems to be, in future, an attractive choice for the relief of acute and chronic symptoms in diabetic neuropathy, but further detailed studies are necessary to find optimum MF parameters, modes of application, and “time windows.”     

Host response to tissues placed in the anterior chamber of the eye: demonstration of migration inhibition factor and serum blocking activity.

Allograft immunity of rats to transplantation antigens was demonstrated by in vitro migration inhibition procedures. Spleen cell suspensions from rats sensitized to histocompatibility antigens by skin graft or anterior chamber implants failed to migrate normally in vitro when incubated in the presence of appropriate donor tissue extracts. Tissue grafts transplanted across both major and minor histocompatibility barriers had prolonged survival within the anterior chamber. However, 2 weeks after implantation, the recipient rats showed detectable sensitization to their implants. Serum from 14- to 32-day implant-bearing rats blocked the migration inhibition found in the implanted rats in the presence of corresponding tissue antigen. Such blocking activity was undetectable in the serum from rats which had implants for 7 days or after rejection of the implant was evident. MIF production in implanted and skin-grafted rats was evident at significantly different times in relation to the graft rejection. The asynchrony of MIF synthesis observed in these experimental animals leads us to postulate that the graft rejection and MIF production may be mediated by distinct lymphocyte populations. In addition, the route of the antigen presentation may account in part for the observed differences.     

Engrafting fetal liver cells into multiple tissues of healthy adult mice without the use of immunosuppressants

We have shown the fetal liver cell engraftments into multiple tissues of adult healthy mice, achieved without suppressing the animals’ immune systems. Fetal cells from the livers of male C57Bl/6J Black lineage mice at day 13 to 15 of gestation were injected intravenously into female adult CC57W/MY White mice. The grafting was evaluated by Y-chromosome-specific PCR, cytometric analysis of fluorescently stained donor cells, and histological analysis. All the methods consistently showed the presence of multiple engraftments randomly distributed through the various organs of the recipients. After 60 days, the grafts still constituted 0.1 to 2.75% of the tissues. The grafted cells did not change their appearance in any of the organs except the brain, where they became enlarged. Inflammatory reactions were not detected in any of the histological preparations. The frequency of engraftments was higher in the liver, indicating that similarity between the donor and recipient cells facilitates engraftment. The high inherent plasticity of fetal liver cells underlies their ability to integrate into healthy recipient organs, which can be governed by environmental conditions and connections with neighboring cells rather than by the initial cellular developmental programs. The fact that fetal liver cells can be grafted into multiple tissues of healthy animals indicates that they can be used to replace the natural loss of cells in adult organisms.     

60 Hz magnetic field exposure and urinary 6-sulphatoxymelatonin levels in the rat

Four separate experiments were carried out to investigate the effect of extremely low frequency magnetic field (MF) exposure (60 Hz, 1 mT rms) on urinary 6-sulphatoxymelatonin (aMT6s) levels in Sprague-Dawley rats. In the first experiment, immature male rats maintained under a regular 12 h daily photoperiod (white fluorescent light) were exposed to a 20 h daily MF exposure for 6 weeks. The second experiment was similar to the first, except that the MF exposure was limited to 10 days. In the third experiment, adult male rats acclimated to a combination of continuous dim red light and regular 12 h daily photoperiod (white fluorescent) were subjected to a single 1 h exposure to intermittent MF (1 min on and 1 min off cycles), 2 h before fluorescent lights went off. The fourth experiment was similar to the third, except that the animals received 2 consecutive days of 20 h daily exposure to intermittent MF, beginning 1 h before the fluorescent lights went off each day. In all four experiments, the circadian profile of urinary aMT6s was examined before, during, and after the MF exposure. No significant effect of 1 mT MF on indoleamine metabolism was observed in any of the above experiments. However, in one of the experiments (no. 4), both the control and the MF groups showed a lower aMT6s level during the exposure days, when compared with that of pre- and post-exposure days, suggesting that the existence of possible effects with lower field strengths at the range of stray field cannot be ruled out. Bioelectromagnetics 19:172–180, 1998. © 1998 Wiley-Liss, Inc.     

Comparison of long-term immunosuppression for limb transplantation using cyclosporine, tacrolimus, and mycophenolate mofetil: implications for clinical composite tissue transplantation

This study compared the efficacy of long-term intermittent immunosuppression in preventing the rejection of a limb transplant across the strongest histocompatibility barrier in ACI --> Lewis rats using the conventional immunosuppressive agent cyclosporine-A and the newer immunosuppressive agents FK-506 (tacrolimus) and RS-61443 (mycophenolate mofetil). The recipient animals were immunosuppressed daily for 14 days postoperatively, followed by long-term intermittent, twice-weekly immunosuppression using cyclosporine 25 mg/kg, RS-61443 30 mg/kg, or FK-506 2 mg/kg. All three immunosuppressive agents were able to prolong the rejection of the skin component of a limb transplant compared with nonimmunosuppressed controls. Eight of nine animals receiving cyclosporine immunosuppression showed signs of rejection of the skin component of the limb transplant while continuing to receive long-term immunosuppression and had a mean rejection time of 61.6 days. Seven of 10 animals immunosuppressed with RS-61443 also showed signs of rejection while still receiving immunosuppression, with a mean rejection time of 43.6 days. Nine of 10 animals receiving FK-506 immunosuppression showed no signs of skin rejection, but died of bacterial pneumonia between 273 and 334 days after transplantation, with a mean rejection time of 296.1 days. There was no statistically significant difference between intermittent immunosuppression with cyclosporine and RS-61443, but FK-506 was significantly superior to both cyclosporine and RS-61443. The implication of this study is that FK-506, but not cyclosporine or RS-61443, is probably the only single immunosuppressive agent capable of preventing rejection of the skin component of a composite tissue transplant. Combination immunosuppression with FK-506 and RS-61443, therefore, may be required to allow composite tissue transplantation to become a predictable clinical reality in the future.     

Effects of 60 Hz magnetic field exposure on the pineal and hypothalamic-pituitary-gonadal axis in the Siberian hamster (Phodopus sungorus)

Experiments using the dwarf Siberian hamster Phodopus sungorus were carried out to determine possible neuroendocrine consequences of one-time and repeated exposures to 60 Hz magnetic fields (MF). Animals were maintained in either a short-light (SL, 8 h light:16 h dark) or long-light (LL, 16 h light:8 h dark) photoperiod. Acute (one-time, 15 min) exposure of male SL animals to a linearly polarized, horizontally oriented, 60 Hz MF (0.1 mT) gave rise to a statistically significant (P < .005) reduction in pineal melatonin content as determined 3 and 5 h after onset of darkness. In LL animals, acute exposure to 0.10 mT resulted in a significant decrease in pineal melatonin as measured 4 h after onset of darkness, whereas acute exposure to 50 microT showed no effect compared with sham exposure. In SL animals, an increase in norepinephrine was observed in the medial basal hypothalamus (including the suprachiasmatic nucleus) after acute exposure (P < .01). Daily MF exposure of SL animals to a combination of steady-state and on/off 60 Hz magnetic fields (intermittent exposure) at 0.1 mT for 1 h per day for 16 days was associated with a reduction in melatonin concentrations at 4 h after onset of darkness and an increase in blood prolactin concentrations (P < .05). Exposure of SL animals to a steady state 60 Hz MF for 3 h/day for 42 days resulted in a statistically significant reduction in body weight (ANOVA: P > .05), compared with sham-exposed SL animals. At 42 days, however, no significant changes in overnight melatonin or prolactin levels were detected. In both repeated exposure experiments, gonadal weights were lowest in the MF-exposed groups. This difference was statistically significant (P < .05) after 42 days of exposure. These data indicate that both one-time and repeated exposure to a 0.1 mT, 60 Hz MF can give rise to neuroendocrine responses in Phodopus.     

Influence of stress of a maternal organism on the turnover of catecholamines in the brain of early postnatal rats

Effects of prenatal stress (daily 1-h-long immobilization of pregnant females at the 15th–21st days of pregnancy) on the formation of sex-related dimorphism of the turnover of noradrenaline (NA) and dopamine (DA) in the preoptic area (POA) of the brain and mediobasal hypothalamus (MBH) were studied in 10-day-old rats. Sex-related differences of the turnover of a functional NA pool in the POA and DA pool in the MBH were demonstrated in intact control rats: a higher rate of the monoamine turnover was observed in males. Prenatal stress abolished these sex-related differences and, at the same time, induced such differences in the DA turnover in the POA. It is supposed that prenatal stress-evoked early modifications of sex-related dimorphism of the catecholamine turnover in the brain can result in the development of remote disturbances in the neuroendocrine control of reproduction and adaptation.     

Action of cortical extracts of the left and right hemispheres on the recovery of conditioned reflex activity in rats after unilateral removal of the frontal cortex

The recovery of active avoidance conditioned reflex (AACR) was investigated after unilateral frontal cortex extirpation. Intraperitoneal injection of extracts from left or right brain cortex (1 mg/kg) of healthy rats (LE or RE) stimulated AACR recovery in animals with lobectomy on the same side. If RE was extracted 9 days after left side brain extirpation, i.e. during the period of the development of compensatory processes, its effect on AACR recovery was stronger in left-operated animals, while in right-operated animals it remained unchanged.     

Effect of stress experienced during pregnancy on the rate of lipid peroxidation in erythrocytes and brain tissue of newborn rat pups

The rate of lipid peroxidation (LPO) in erythrocytes and brain homogenate has been assessed by the accumulation of malondialdehyde, the degree of erythrocyte autohemolysis, the content of hydrogen peroxide and catalase activity observed in newborn rats aged 1 hour, 1, 15, 20 and 30 days. Pregnant rats were exposed to emotional stress (aggressive interaction of two pregnant rats in an unavoidable conflict situation provoked by nociceptive irritation. Significant age-dependent differences in the rate of LPO (both in erythrocytes and cerebral tissue) have been found. The highest rate was noted in rats 15 days of age. The emotional stress of pregnant females resulted in the changes of behavioural reactions of newborn rats and LPO activity that was characterized by the increase in LPO rate in 1-hour- and 1-day-old rats and by slowing of LPO rate in 15-day-old rats. These phenomena were observed in erythrocytes and brain tissues of test animals.     

Changes in the learning ability of epiphysectomized rats

The experiments on rats have shown changes in the learning ability of animals. The learning of locomotor reactions of escape and avoidance conditioned reflex was accelerated in animals after pinealectomy. Training of rats in U-shaped and 16-door mazes was significantly affected after pinealectomy. The index of reflex retention (1 and 7 days later) was not changed in the operated animals. Epithalamin (0.5 mg/kg for 5 days) selectively facilitated learning of visual and space discrimination.     

Effect of exposure to 50 Hz magnetic field with or without insulin on blood–brain barrier permeability in streptozotocin‐induced diabetic rats

We investigated the effect of long‐term exposure to modulation magnetic field (MF), insulin, and their combination on blood–brain barrier (BBB) permeability in a diabetic rat model. Fifty‐three rats were randomly assigned to one of six groups: sham, exposed to no MF; MF, exposed to MF; diabetes mellitus (DM), DM induced with streptozotocin (STZ); DM plus MF (DMMF); DM plus insulin therapy (DMI); and DM plus insulin therapy plus MF (DMIMF). All the rats underwent Evans blue (EB) measurement to evaluate the BBB 30 days after the beginning of experiments. The rats in MF, DMMF, and DMIMF groups were exposed to MF (B = 5 mT) for 165 min every day for 30 days. Mean arterial blood pressure (MABP), body mass, and serum glucose level of the study rats were recorded. The extravasation of brain EB of the MF, DM, DMMF, DMI, and DMIMF groups was higher than that of the sham group and the extravasation of right hemisphere of the DMIMF group was highest (P < 0.05). The post‐procedure body mass of the sham and MF groups were significantly higher than those of the DM and DMMF groups (P < 0.05). In the DM, DMMF, DMI, and DMIMF groups, the baseline glucose was significantly lower than the post‐procedure glucose (P < 0.05). DM and MF increase BBB permeability; in combination, they cause more increase in BBB permeability, and insulin decreases their effect on BBB. Improved glucose metabolism may prevent body mass loss and the hypoglycemic effect of MF. DM increases MABP but MF causes no additional effect. Bioelectromagnetics 31:262–269, 2010. © 2009 Wiley‐Liss, Inc.     

Changes in the sensitivity of brain dopamine and serotonin receptors during the prolonged administration of carbidine

Male Wistar rats were treated chronically with either carbidine (10 mg/kg/day) or haloperidol (1 mg/kg/day) for 23 consecutive days. On days 4-5 after the treatment discontinuation the animals were challenged with apomorphine HCl (0.5 mg/kg) or 5-OTP (150 mg/kg i. p) in combination with pargiline (40 mg/kg i. p) and stereotype responses were scored. In carbidine-treated rats the intensity of stereotype sniffings was increased after apomorphine treatment. In contrast, animals treated with haloperidol exhibited more intensive gnawing after apomorphine in comparison to vehicle-treated rats. 5-OTP-induced head twitches were increased only in carbidine-treated rats. Prolonged carbidine treatment in contrast to haloperidol induced a decrease in 5H-spiperone and 3H-LSD binding in the frontal cortex, with the density of D-2 receptors in the striatum practically unchanged. It is concluded that neuroleptic carbidine in contrast to classical neuroleptics has a more selective effect in serotonin (S-2) receptors and antidepressive properties of this compound may be due to the down-regulation of S-2 receptors in the brain.     

Administration of the stress protein gp96 prolongs rat cardiac allograft survival, modifies rejection-associated inflammatory events, and induces a state of peripheral T-cell hyporesponsiveness

High-dose gp96 has been shown to inhibit experimental autoimmune disease by a mechanism that appears to involve immunoregulatory CD4+ T cells. This study tested the hypothesis that high-dose gp96 administration modifies allograft rejection and associated inflammatory events. Wistar cardiac allografts were transplanted into Lewis recipient rats and graft function was monitored daily by palpation. Intradermal administration of gp96 purified from Wistar rat livers (100 microg) at the time of transplantation and 3 days later significantly prolonged allograft survival (14 vs 8 days in phosphate-buffered saline [PBS]-treated recipients; P = 0.009). Rejected allografts from gp96-treated animals were significantly less enlarged than allografts from their PBS-treated counterparts (2.8 vs 4.3 g; P < 0.004). Gp96 was also effective when administered on days 1 and 8 (13 vs 7 days), but not if it was derived from recipient (Lewis) liver tissue or administered on days 0, 3, and 6. In parallel studies, CD3+ T cells from gp96-treated untransplanted animals secreted less interleukin (IL)-4, IL-10, and interferon (IFN)-gamma after in vitro polyclonal stimulation than CD3+ T cells from PBS-treated animals. Gp96 administration might therefore influence the induction of immunity to coencountered antigenic challenges and inflammatory events by inducing what appears to be a state of peripheral T-cell hyporesponsiveness.     

Catecholamine Concentration in the Developing Rat Brain after γ-Hydroxybutyric Acid

The effect of the GABA receptor agonist γ-hydroxybutyric acid (GHBA) on brain catecholamine concentration was investigated in 1 to 28 day old rats. The infant rats were given GHBA in various doses (375–1500 mg/kg) and the effects on whole brain or regional brain concentration of dopamine (DA) and noradrenaline (NA) were measured. Brain DA concentration increased in a dose-dependent way already from two days of postnatal age. In the regional brain study of the 14- and 28-day-old animals the increase in DA concentration was found to be almost exclusively located in the striatal region. Generally, no changes in NA concentration were found in the whole brain or various brain regions at any of the ages after GHBA. It is concluded that the inhibitory striatal-nigral neurons, utilizing GABA as a transmitter, are functionally developed during early postnatal age.