Anti-asialo GM1 antibodies prevents guanethidine-induced sympathectomy in athymic rats.

Guanethidine sulphate induces destruction of peripheral sympathetic neurons and infiltration of mononuclear cells in rat sympathetic ganglia. The effect of guanethidine is believed to be an autoimmune reaction. In order to determine the effect of anti-asialo GM1, an antibody that binds to the glycolipid asialo GM1 expressed on rodent natural killer cells, athymic Lewis rats received guanethidine 40 mg/kg i.p. daily from day 1 to 14 and anti-asialo GM1 i.p. 1 mg/rat on day -2, 0, 2, 6, and 10 in the study period. Saline and anti-asialo GM1 were given alone in the same doses as control. The number of neurons in the sympathetic ganglia were counted and the ganglionic volume determined. The presence of natural killer cells in the ganglia were determined by immunohistochemical methods. Our results shows that anti-asialo GM1 can prevent guanethidine-induced reduction of sympathetic neurons, but not prevent the initiation of an immunological reaction in the ganglia. Natural killer cells could only be identified in ganglia following guanethidine treatment alone. It is concluded that anti-asialo GM1 treatment can prevent the guanethidine-induced sympathectomy by eliminating the natural killer cells from the ganglia.     

Effect of immunosuppressive agents on the guanethidine-induced sympathectomy in athymic and euthymic rats.

Guanethidine sulphate causes destruction of peripheral sympathetic neurons and infiltration of mononuclear inflammatory cells in the sympathetic ganglia of both athymic nude (rnu/rnu) and euthymic LEW/Mol rats. The effect of guanethidine is believed to be an autoimmune reaction. To determine the effect of immunosuppressive drugs concurrently with guanethidine treatment both athymic and euthymic rats were treated with guanethidine 40 mg/kg i.p. daily for 14 days, cyclophosphamide 100 mg/kg i.p. on days 1 and 8, methylprednisolone 10 mg/kg and cyclosporin A 10 mg/kg daily from days 1 to 7, and then every other day from days 8 to 14. The number of neurons in the sympathetic ganglia was counted and four subpopulations of mononuclear inflammatory cells were identified by monoclonal antibodies MHC II, CD8 T-cells/NK-cells, CD5 T-cells, CD4 T-cells/macrophages. Our results show that the immunosuppressive drugs used were unable to prevent the guanethidine-induced reduction of sympathetic neurons, although the number, of neurons following guanethidine-methylprednisolone treatment was significantly higher compared with guanethidine alone in both athymic and euthymic rats. The identification of mononuclear cells in the sympathetic ganglia showed that the CD8/NK and CD5 populations were the populations primarily responding to guanethidine treatment. Both CD8/NK and CD5 populations were absent without guanethidine, but increased significantly following guanethidine in both athymic and euthymic animals. None of the immunosuppressive drugs used could prevent the guanethidine-induced rise in the CD8/NK population in neither athymic nor in euthymic rats. The rise in the CD5 population was suppressed following treatment with all immunosuppressive drugs in athymic rats, but only following methylprednisolone in euthymic animals. These results indicate that guanethidine induces proliferation of T-cells in euthymic rats and non-functional CD5 positive pre T-cells in athymic animals. The CD5 population in both athymic and euthymic animals appears relatively more sensitive to immunosuppressive drugs than the NK-cell population also activated by guanethidine. This relatively resistant NK-cell population seems to play an important role in the guanethidine-induced destruction of sympathetic neurons and can explain why the guanethidine-induced immunological reaction could not be fully prevented by the immunosuppressive drugs used. The conclusion is that guanethidine induces destruction of sympathetic neurons by a NK-cell-mediated reaction.     

Identification of the mononuclear cell infiltrate in the superior cervical ganglion of athymic nude and euthymic rats after guanethidine-induced sympathectomy

Guanethidine sulphate 40 mg/kg intraperitoneally for 14 days induced chromatolysis and nerve cell death in the superior cervical ganglia of athymic nude (rnu/rnu) LEW/Mol rats and their euthymic (+/rnu) LEW/Mol heterozygous littermates. Histologically the sympathetic ganglia were dominated by an infiltration of small inflammatory cells. By means of monoclonal antibodies these cells were identified. The number of B-lymphocytes increased following guanethidine in both athymic and euthymic rats. The number of T-lymphocytes increased to a great extent in euthymic rats, but was virtually missing in athymic rats. The number of NK-cells and monocytes/macrophages increased in both athymic and euthymic rats. The conclusion is, that guanethidine exerts a direct effect on sympathetic ganglion cells followed by a thymus-independent immune response.     

Effects of guanethidine-induced sympathectomy on morphology of the pre- and postclosure lleum of the neonatal rat

The disappearance of the characteristic supranuclear vacuole and extensive apical canalicular system from enterocytes of the ileal villi occurs during the third postnatal week in rats. This phenomenon is associated with loss of permeability of these cells to macromolecules and is therefore termed closure. The present study was designed to analyze the influence of neonatal guanethidine (GTN)-induced sympathectomy on the morphology of the pre- and postclosure ileum of the rat. Light and electron microscopy of control and GTN-sympathectomized rats demonstrated the retention of immature, vacuolated cells on ileal villi as late as 23 days postnatally in GTN-treated rats. Villi from control rats contained only adultlike nonpermeable cells. Electron microscopy further demonstrated no structural differences in the apical canalicular system or storage vacuoles of the delayed cells in GTN rats when compared to the ileal epithelium from preclosure time periods (7 and 15 days) in both GTN-sympathectomized and control rats. Goblet cells were counted on Periodic-Acid-Schiff-stained sections of ileum from 7, 15, and 23-day GTN and control rats. The percentage of goblet cells in the total epithelial cell population of the villus was significantly higher in control versus GTN rats at all time periods. The percentage of goblet cells increased in both groups from day 7 to 15. However, closure in the control group (approximately day 18) was coincident with a steep increase in the percentage of ileal goblet cells which was not evident in the goblet-cell population of the GTN villus. This pattern of change in control versus GTN goblet-cell production was correlated with a similar pattern of variation in the number of crypt cell mitoses between the two groups over the same time period.     

Degeneration patterns of postganglionic fibers following sympathectomy

Summary In cats the time course of degeneration following lumbal sympathectomy was studied in the ramus communicans griseus (reg) and in the nerves to the triceps surae muscle using light and electron microscopic methods.The left lumbar sympathetic trunk including its rami communicantes was removed from L2 to S1 using a lateral approach. The animals were sacrificed between 2 and 48 days after the sympathectomy. Tissue samples were taken (a) one cm proximal to the entrance of the rcg into the spinal nerve, and (b) one cm proximal to the entrance of the nerve into the muscle belly.In the reg signs of degeneration can already be recognized in the myelinated as well as in the unmyelinated axons 48h after sympathectomy. The degenerative processes in the axons reach their peak activity at about 4 days p.o. They end a weck later. Signs of the reactions of the Schwann cells and of the endoneural cells can first be seen 2 days p.o. They are most pronounced around the 8th day p.o., and last at least up to the third week. Thereafter the cicatrization processes settled to a rather steady state (total observation period 7 weeks).In the muscle nerves the first signs of an axonal degeneration of the sympathetic fibers can be recognized 4 days after surgery. The signs of axonal degeneration are most striking about 8 days p.o. They have more or less disappeared another week later. The reactions of the Schwann cells also start on the fourth day but outlast the degenerative processes by some 8 days. Thus the degenerative and reactive processes in the reg precede those in the muscle nerves by 2 days early after surgery and by 6 days 3 weeks later. Seven weeks after surgery, fragments of folded basement lamella and Remak bundles with condensed cytoplasm and numerous flat processes are persisting signs of the degeneration.In addition to the differences in time course between the proximal and the distal site of observation, it was also noted that both the axonal degeneration and the reactions of the Schwann cells are more pronounced in the rcg than in the muscle nerve. For example there was abundant mitotic activity in the central endoneural and Schwann cells whereas we could not detect such activity in the periphery.It is concluded that the time course of degeneration and the intensity of the degenerative and reactive processes is, to a considerable extent, determined by the distance between the site of nerve section and the site from which the specimen is taken. Many of the conflicting data in the literature can be explained by this finding.     

Carotid chemoafferent plasticity in adult rats following developmental hyperoxia

Developmental hyperoxia impairs carotid chemoreceptor development and induces long-lasting reduction in carotid sinus nerve (CSN) responses to hypoxia in adult rats. Studies were carried out to determine if CSN responses to acute hypoxia would exhibit hypoxia-induced plasticity in adult 3-5-months-old rats previously treated with postnatal hyperoxia (60% O2, PNH) of 1, 2, or 4 weeks duration. CSN responses to acute hypoxia were assessed in adult rats exposed to 1 week of sustained hypoxia (12% O2, SH). In normal adult rats and adult rats treated with 1 week of PNH, CSN responses to acute hypoxia were significantly increased in urethane-anesthetized rats when studied 3-5 h after SH. Apparent increases in CSN responses to hypoxia were not significant in rats treated with 2 weeks of PNH and were clearly absent after 4 weeks of PNH, but exponential analysis suggests a PNH duration-dependent plasticity of the CSN response to acute hypoxia after SH. In a second study rats exposed to 2 weeks of PNH were treated with SH for 1 week as adults and acute hypoxic responses were tested 4-5 months later. CSN responses in these rats were unaffected by SH suggesting a lack of persistent SH-induced functional plasticity. We conclude that rats treated with 1 week of PNH retain the capacity for hypoxia-induced plasticity of carotid chemoafferent function and some potential for plasticity may be present after 2 weeks of PNH, whereas 4 weeks of PNH impairs the capability of rats to exhibit plasticity following 1 week of SH.     

Degeneration secretion of saliva in the rat following sympathectomy

1. After previous extirpation of the superior cervical ganglion saliva was found to flow from the cannulated submaxillary duct of rats under chloralose anaesthesia. The secretion started 13-14.5 hr after sympathectomy, increased gradually in rate and then slowed down and ceased, lasting for about 12 hr.2. Injection of alpha- or beta-adrenoreceptor blocking drugs reduced the flow and a combination of both types of drugs abolished it. It is concluded that the secretion was caused by noradrenaline released from the degenerating nerves, and that the phenomenon is an example of the degeneration activity described in other preparations as an effect of section of post-ganglionic autonomic nerves.3. A similar, but less pronounced, secretion was found in the parotid gland of the rat.     

Ureteral axon damage following subcutaneous administration of capsaicin in adult rats

Systemic administration of capsaicin to adult rats results in the death of almost 90% of the axons in the ureter. Because of the massive axon loss we presume that sensory and possibly some sympathetic axons are killed. By contrast sensory axons in the dorsal root do not seem to be affected. We speculate that the axons in the ureter die because they are not protected by sleeves of perineurium. This hypothesis will be tested in subsequent work.     

Taste aversion following backward conditioning procedures in preweanling and adult rats

Laboratory rats, 18 and 90 days old, received an intraperitoneal injection (2% body weight) of .15M lithium chloride or .9% saline 10 or 30 min before 15-min access to 12% sucrose. Additional control groups received LiCl injection followed by tap water access. Testing with a 2-bottle choice procedure revealed reliable aversion effects for both age groups at each toxicosis-flavor interval. Adult rats showed reliably greater persistence of aversion following training with the 10- than with the 30-min interval. Rat pups showed no reliable differences in aversion across training intervals. Reliably greater aversion effects occurred for adults than for pups following training at the 10-min interval. Following training at the 30-min interval a similar reliable age effect occurred on Test Trial 1; but from Trial 2 onward the magnitude of aversion was similar for pups and adult rats.     

Intranasally delivered bFGF enhances neurogenesis in adult rats following cerebral ischemia

Basic fibroblast growth factor (bFGF) is a very important mitogenic factor with proved neurogenesis effects in the central nervous system. Intranasal administration can bypass blood-brain barrier and deliver drugs into the brain directly. We investigated whether intranasal administration of bFGF at later time points after ischemia could promote adult neurogenesis and improve neurologic functions. Rats received bFGF or saline intranasally once daily for 6 consecutive days, starting at 1 day after transient middle cerebral artery occlusion (MCAO). Bromodeoxyuridine (BrdU) was injected at 5 and 6 days after MCAO. Rats were killed at 7 or 28 days after MCAO. Neurogenesis was assessed by immunostaining for BrdU and cell type-specific markers. Neurological functions were evaluated by the modified Neurological Severity Scores. Compared with the control animals, intranasal administration of bFGF improved behavioral recovery without affecting infarct size, and enhanced proliferation of progenitor cells in the subventricular zone and the subgranular zone of the dentate gyrus (DG). Furthermore, the new proliferated cells could differentiate into neurons (BrdU+NeuN+ cells) in the striatum and DG at 28 days after MCAO. Intranasal administration of bFGF offers a non-invasive alternative for the treatment of stroke.     

Persistence of vibrissal motor representation following vibrissal pad deafferentation in adult rats

The effect of sensory vibrissal pad denervation on M1 organization was studied in adult rats 2 weeks after the infraorbital nerve was severed. Cortical motor output organization was assessed mapping the representation size and thresholds of vibrissa movements evoked by intracortical electrical microstimulation (ICMS). Motor cortex output patterns of control and sham groups of rats were compared with those of rats that had received unilateral or bilateral infraorbital nerve lesions. The mean size of the vibrissa representation in both unilateral and bilateral input-deprived hemispheres was not significantly different from those in control and sham hemispheres. The mean threshold required to evoke vibrissa movements was significantly higher in both groups of deafferented hemispheres than in control and sham groups of hemispheres. In contrast, the mean threshold required to evoke other types of movements from both groups of input-deprived hemispheres were similar to those found in the control and sham groups of hemispheres. These results indicate that input-deprived vibrissal motor representation reflects lower-than-normal excitability, although the size and topographic relationship with neighboring representations are normal.     

Reinnervation of the dentate gyrus and recovery of alternation behavior following entorhinal cortex lesions

Adult male rats were implanted with chronically indwelling recording electrodes in the dentate hilus of one hemisphere and bipolar stimulating electrodes in the contralateral entorhinal cortex (EC). Daily measurements were then made of the amplitude of responses, evoked through the crossed temporodentate (CTD) pathway, while the rats were unanesthetized and unrestrained. The implanted rats were also trained to alternate turns in a T-maze, with the use of a rewarded-alternation procedure. After reaching criterion performance in the alternation task, each rat was given a lesion of the EC ipsilateral to the recording electrode (n = 14) or a sham lesion (n = 5). Mean amplitudes of the evoked responses increased over Postlesion Days 4-11, probably due to reactive synaptogenesis in the CTD system, reaching a level that was significantly elevated above prelesion levels by Postlesion Day 6. Rats given EC lesions exhibited a transient impairment in alternation performance, with the mean alternation score significantly below prelesion levels on Postlesion Days 2-6. Although 2 EC-lesioned rats did not show a behavioral deficit, the electrophysiological increases and behavioral recovery were correlated in the remaining 12 cases (Pearson r = .73). These results are consistent with the interpretation that sprouting by the CTD system contributes to recovery of T-maze alternation performance following unilateral EC lesions.     

Altered social interaction in adult rats following neonatal treatment with domoic acid

Schizophrenia is a debilitating neurological disorder characterized by positive, negative, cognitive and/or emotional symptoms. Decreased social interaction is a common negative symptom. Social interaction can be readily observed in rats and is therefore an ideal target behaviour when evaluating an animal model of schizophrenia. The purpose of this study was to determine whether early alterations in glutamate signaling resulted in social withdrawal; a finding which would be consistent with existing animal models of schizophrenia and is observed within the clinical population. In the present study, male and female SD rat pups received daily injections (s.c.) of very low doses of the glutamate agonist domoic acid (DOM; 20 microg/kg) or saline during a critical period of CNS development (i.e., PND 8-14). As adults, rats were assessed for degree of social interaction. During testing, each test rat was placed in a social interaction arena and scored for social contact with and avoidance of, a same-sex untreated conspecific. No differences were found in overall activity, nor were differences present for time spent engaged in neutral behavior (i.e., not engaged in behaviour, either directed toward or in avoidance of, the stimulus rat). However, domoate-treated male rats demonstrated evidence of social withdrawal, as evidenced by a significantly greater amount of time spent in avoidance behaviour and a significantly less amount of time spent engaged in social contact. These findings are discussed in context of the significance of early alteration to glutamate signaling in the development of human neuropathological disorders.     

Wheel-running behavior is altered following withdrawal from repeated cocaine in adult rats

The residual effects on open-field habituation and self-generated wheel running following withdrawal from repeated cocaine (COC; 30 mg/kg for 7 days) were examined in adult male rats. Control subjects received equivolumetric injections of saline (SAL) and were either allowed to feed ad libitum or pair-fed matched (PF SAL) to COC subjects to control for the drug's potential anorexic effect. Following 10 days of withdrawal, all subjects were examined twice on each of the two assessment instruments. Results indicated that COC subjects over the two test sessions failed to increase their wheel-running rates and did not show the expected habituation in the open field. However, because both COC and PF SAL groups yielded similar effects in the open field, conclusions about cocaine's consequences on habituation could not be established independent of the drug's anorexic effect. These data provide evidence for the view that repeated cocaine impairs motivational processes responsible for engaging in self-generated naturally rewarding behaviors. Speculation concerning the neurobiobehavioral substrates for this effect is presented.     

内皮素-B受体在脑缺血大鼠脑内小胶质细胞中的表达

目的 研究脑缺血后内皮素-B(ET-B)受体在脑内激活的小胶质细胞中的表达变化,探讨ET-B受体与脑缺血的关系.方法 应用微创开颅法建立大鼠大脑中动脉闭塞(MCAO)模型,81只大鼠随机分为2h、6h、12h、1d、2d、3d和1周7个缺血组,以及正常对照组和假手术组(n=9).用抗凝集素(lectin)和抗ET-B抗...     

Suppression of adult copulatory behaviors following LiCl-induced aversive contingencies in juvenile male rats

Sexually immature juvenile male rats received an injection of .3 M (20 ml/kg) lithium chloride (LiCl) during each of 8-10 pairings (spaced at 2-3-day intervals) with an estrous female. Approximately seven weeks later, these males displayed fewer copulatory behaviors in pairings with estrous females than saline control rats. Noncontingent .3 M LiCl injections administered to juvenile males did not affect adult copulatory behaviors. Males that were either group or individually housed during the retention interval displayed comparable suppression, which suggests that copulatory suppression does not represent a generalized aversion to social interactions with another animal. Males housed during the retention interval in an environment that contained the odors of estrous females also displayed suppression comparable to that of males housed in the absence of such odors. This suggests that the associations that mediate copulatory suppression are not elicited solely by the odor cues of estrous females. These data demonstrate that LiCl-induced aversive contingencies in juvenile male rats subsequently suppress adult copulatory behaviors.     

Plasma testosterone concentration in adult male rats following acquisition of copulation-illness associations.

Prior research has identified stimuli and procedures that elicit increments in plasma testosterone in copulating male rats. In the present experiment, we demonstrate that associative inhibition of copulatory behaviors in male rats is not correlated with and cannot be attributed to a conditioned suppression of testosterone. Each male rat was paired with an inaccessible estrous female for 7 min and was then given an opportunity to copulate. Two groups received an injection of either lithium chloride (LiCl; 0.3 M, 20 ml/kg, IP) or saline (0.3 M, 20 ml/kg, IP) immediately after each of 11 pairings spaced at 3- to 4-day intervals. A third group received a noncontingent injection of LiCl 24 h after each pairing. After an initial screening for copulatory behaviors, a fourth group received only handling comparable to that received by the other three groups. Rats that received contingent LiCl gradually ceased to copulate; rats that received either noncontingent LiCl or saline remained vigorous copulators. Male rats were returned to their home cages on Trial 12 after 7-min exposure to an inaccessible female. Blood was collected by decapitation 38 min later. Testosterone levels, measured by radioimmunoassay, were significantly higher for saline than for handled control rats. Testosterone levels for handled control rats, however, were comparable to those of copulating and noncopulating rats that had received either noncontingent or contingent LiCl, respectively.     

Dietary obesity in adult and weanling rats following removal of interscapular brown adipose tissue

In order to investigate the role of brown adipose tissue (BAT) in diet-induced thermogenesis (DIT), a selection of palatable, energy-dense foods (Cafeteria diet) was used to increase the energy intakes of adult and weanling male rats, from some of which interscapular BAT (IBAT) had been surgically excised. Removal of IBAT had no effect upon energy intakes of the cafeteria-fed rats, nor of controls fed a pelleted stock diet. The rate of weight gain of intact controls was similar for the two diets, but adults with IBAT removed and fed with the cafeteria diet gained weight more rapidly than those fed the stock diet. Similarly, although intact weanlings did not exhibit excess weight gain when fed the cafeteria diet, removal of IBAT did result in more rapid weight gain of the cafeteria-fed weanlings relative to their stock-fed siblings. Nevertheless, total carcass energy was increased by some 20% in cafeteria-fed animals, irrespective of whether they had had IBAT removed. Thus there was no evidence for removal of IBAT having improved the efficiency of energy utilisation for growth. The failure to find evidence for altered levels of energy expenditure following removal of IBAT does not necessarily contradict the hypothesis that BAT mediates DIT, however, since, following removal of IBAT, there was hypertrophy of remaining BAT sites which may have compensated for the BAT removed.     

Induction of maternal behavior in adult female rats following chronic morphine exposure during puberty

The peripubertal period in the female rat is the time when the stimulatory effects of opioids on prolactin (PRL) secretion develop. In the adult rat, the administration of chronic high-dose morphine has been shown to attenuate the ability of opiates to stimulate PRL secretion. One function of PRL in adult virgin rats is the induction of maternal behavior. The present study examined whether chronic high-dose morphine exposure during the peripubertal period alters PRL-mediated induction of maternal behavior in adult female rats. Two groups of juvenile female rats were administered increasing doses of morphine or vehicle (s.c.) from age 30 to 50 days. As adults, these females either remained intact, or were ovariectomized and treated with a PRL-dependent, steroid hormone regimen that stimulates a rapid onset of maternal behavior. All females were then exposed daily to rat foster pups to determine whether peripubertal morphine exposure affected their latencies to induce maternal behavior. Morphine treatment resulted in a delay in vaginal opening and a temporary reduction in the rate of weight gain; however, the rate of onset of maternal behavior was unaffected by peripubertal morphine treatment. Thus, chronic morphine exposure in the pubertal female did not impact the expression of pup-induced maternal care.