Orexin-A does not stimulate food intake in old rats

Aging is associated with a progressive decrease in appetite and food intake. Both A and B orexins, expressed in specific neurons of the lateral hypothalamic area, have been implicated in the regulation of sleep and feeding. In this study, the stimulatory effect of intracerebroventricular administration of the orexins on food intake was compared between young (4-mo-old) and old (25- to 27-mo-old) male Wistar rats. A stainless steel cannula was implanted stereotactically into the left lateral ventricle. After a 7-day recovery period, different doses (0-30 nmol) of orexins were injected into the left lateral ventricle without anesthesia. Food and water consumptions were measured at 1, 2, and 4 h after injection. The protein levels of orexin receptors, a specific receptor for orexin-A (OX1R) and a receptor for both orexin-A and -B (OX2R), in the hypothalamus were determined by Western blot analysis and compared between young and old rats. Intracerebroventricular administration of orexin-A stimulated food intake in a dose-dependent manner in young rats. However, no effects were observed at any dose in old rats. The protein level of OX1R in the hypothalamus was significantly lower in old rats than in young rats, although the protein level of OX2R was comparable between groups. Results of the present study indicate that the function of the orexin system is diminished in old rats. The decrease in the OX1R protein level in the hypothalamus could be responsible for orexin-A's lack of stimulation of food intake in old rats.     

A Novel Rat Model to Study the Role of Intracranial Pressure Modulation on Optic Neuropathies

Reduced intracranial pressure is considered a risk factor for glaucomatous optic neuropathies. All current data supporting intracranial pressure as a glaucoma risk factor comes from retrospective and prospective studies. Unfortunately, there are no relevant animal models for investigating this link experimentally. Here we report a novel rat model that can be used to study the role of intracranial pressure modulation on optic neuropathies. Stainless steel cannulae were inserted into the cisterna magna or the lateral ventricle of Sprague-Dawley and Brown Norway rats. The cannula was attached to a pressure transducer connected to a computer that recorded intracranial pressure in real-time. Intracranial pressure was modulated manually by adjusting the height of a column filled with artificial cerebrospinal fluid in relation to the animal’s head. After data collection the morphological appearance of the brain tissue was analyzed. Based on ease of surgery and ability to retain the cannula, Brown Norway rats with the cannula implanted in the lateral ventricle were selected for further studies. Baseline intracranial pressure for rats was 5.5±1.5 cm water (n=5). Lowering of the artificial cerebrospinal fluid column by 2 cm and 4 cm below head level reduced ICP to 3.7±1.0 cm water (n=5) and 1.5±0.6 cm water (n=4), a reduction of 33.0% and 72.7% below baseline. Raising the cerebrospinal fluid column by 4 cm increased ICP to 7.5±1.4 cm water (n=2) corresponding to a 38.3% increase in intracranial pressure. Histological studies confirmed correct cannula placement and indicated minimal invasive damage to brain tissues. Our data suggests that the intraventricular cannula model is a unique and viable model that can be used to study the effect of altered intracranial pressure on glaucomatous optic neuropathies.     

Simplified surgical placement and stabilization methods for intracerebroventricular cannulas in rat lateral ventricles

Intracerebroventricular cannulation in rat models is an efficient tool for exploring the effects of substances directly injected into the CNS, bypassing the blood-brain barrier. Techniques for surgically securing the ICV cannula require a balance between ease of application and adequate stability. The authors tested several methods of lateral ventricle cannula stabilization, especially focusing on a comparison of cyanoacrylate gel to cranioplastic cement with an anchoring bone screw.     

Orexin-A受体介导的生长抑素激动剂ODT8-SST对大鼠摄食和饮水的影响

目的：探讨orexin-A（OXA）受体介导的生长抑素激动剂ODT8-SST 对大鼠摄食和饮水的调节作用相关作用机制。方法：在光 照周期内,大鼠40 只随机分8 组,侧脑室（icv）分别注射不同剂量ODT8-SST 或生理盐水（NS）;大鼠56 只随机分8 组分别侧脑 室注射不同剂量OXA 受体（OX1R）拮抗剂SB-334867 或NS;2小时后测量大鼠摄食量和饮水量。结果：与NS组相比,实验组大 鼠侧脑室注射ODT8-SST（1 ug/rat）,2 小时后摄食量和饮水量均显著增加（P<0.05）。大鼠侧脑室注射SB-334867（16 ug/rat）完全 抑制了由侧脑室注射ODT8-SST 后引起的摄食量和饮水量的增加;与此相反,大鼠给予SST2 拮抗剂S-406-028 预处理之后,可阻 止侧脑室注射ODT8-SST 引发的促进食欲作用,但不会影响侧脑室注射OXA（10.7 ug/rat）诱导的摄食量和饮水量的增加。结论： 侧脑室注射ODT8-SST 可促进摄食和饮水,该过程可能由OX1R所介导;orexin-A 促进摄食作用不依赖大脑SST2 通路的激活。     

Central antalgic activity of resveratrol

A single dose of resveratrol (25 μg/10μl) was injected directly into the right lateral cerebral ventricle (icv) of Wistar rats via an implanted cannula in order to study the analgesic properties of the compound. A control group of rats received 10 μl NaCl 0.9%. The lengthening of the time to reaction to painful stimuli was assessed in the radiant heat tail-flick latency time test. In this study, the response to painful stimuli of the animals treated with resveratrol had a bimodal profile with hypoalgesia or hyperalgesia. In the selected experimental conditions, resveratrol had a definite analgesic effect; the increase in time to reaction ranged from 100-120% (8 rats) to 600-700% (9 rats). In this experiment resveratrol exerts evident central antalgic effects in the majority of rats, which are related to the individual level of excitation and vigilance at baseline. Antinociceptive induced by resveratrol icv injection was maximal at 4-10 min and lasted no longer than 15 min. The effect of resveratrol to produce analgesia after a single icv injection may be interesting for preventing chronic pain.     

Role of cholecystokinin-A and cholecystokinin-B receptors in anxiety

Evidence from several laboratories indicates that the anxiogenic effects of cholecystokinin (CCK) are mediated by CCKB receptors. However, it has been reported that CCKA receptors have been found in brain and CCKA antagonists have anxiolytic properties. The aim of this work was to study whether CCKA receptors are also involved in the modulation of anxiety. Anxiogenic effects were observed in the elevated plus maze in rats when pure CCKB receptor agonists (CCK-4 and CCK-8 non-sulfated) or CCK-8S, a CCKB/CCKA agonist, were injected into the lateral ventricle. In contrast, CCK-33, a CCKA agonist or CCK-(1-21) and CCK-(26-29) were ineffective. Furthermore, the anxiogenic effects of CCK-8S were prevented by blocking CCKB but not CCKA receptors. Finally, CCK-33 injected into the postero-medial nucleus accumbens failed to affect the anxiety level of the rats. These results indicate that CCKA receptors are not involved in anxiety, as measured by the paradigms used in this work.     

Protein synthesis in rat tissues during lactation. No effect of diethyl ether anaesthesia.

Rates of protein synthesis were measured in mammary gland, liver, intestinal mucosa and muscle of lactating rats by using a flooding dose of [3H]phenylalanine that was injected into diethyl ether-anaesthetized dams via a lateral vein or into undisturbed dams via a jugular cannula. Ether anaesthesia did not alter rates of protein synthesis significantly in any tissue.     

The role of serotonin-modulated anticonsolidation protein in memory formation in rats in a shuttle box

Two series of experiments were carried out in Wistar male rats. In the first series, rats were trained to acquire conditioning in a shuttle box to 50% and 80% learning criteria. In the animals of the experimental group that achieved 50% learning criterion, a significant decrease in the levels of serotonin-modulated anticonsolidation protein (SMAP) (solid phase, indirect ELISA-test) was observed in the temporal cortex as compared to the animals of the active control group. In the animals of the experimental group that achieved 80% learning criterion, such a decrease was found in the occipital and temporal cortex. In the second series of the experiments, animals of the experimental group were injected with SMAP in saline at a concentration of 1.5 mg/ml in a volume of 10 microl through the cannula implanted into the left lateral ventricle of the brain. Control animals were administered with heating-inactivated SMAP in the same amount. The substances were injected to the animals under light ether anesthesia daily 40 min prior to learning sessions. Learning sessions were carried out in the shuttle box for several days to 50% learning criterion. The experimental rats achieved learning criterion within 7-8 days, whereas intact and control animals reached the same criterion within 4 days. Furthermore, the experimental group of animals differed in increased levels of fear, anxiety and aggression which did not decline throughout the whole learning period. The conclusion was made that SMAP participated in negative regulation of the memory trace formation.     

Effects of acute opiate-peptide administration on pro-opiomelanocortin cells of the intermediate lobe of the rat pituitary

Summary The effects of acute injections of synthetic opiate peptides into the lateral cerebral ventricle of young adult male rats on cells of the intermediate lobe of the pituitary were studied. Met-enkephalin (100/g) injected into anesthetized rats, or 20 g beta-endorphin administered via a previously implanted cannula to unanesthetized animals, will lead to cell degranulation and often to expanded Golgi zones and prominent regions of rough endoplasmic reticulum in secretory cells when tissue is fixed 45–60 min after peptide administration. Treatment of animals with the opiate antagonist naloxone hydrochloride prior to enkephalin injection appeared to prevent the cellular changes elicited with peptide alone. Observations suggest that opiate peptides administered to the cerebrospinal fluid may stimulate release of pro-opiomelanocortin-peptide from pituitary cells.     

Comparison of central effects of noradrenaline and dopamine injected into the lateral brain ventricle in rats.

Noradrenaline and dopamine injected into the lateral brain ventricle exerted a significant effect on the behavior of rats. Both amines caused a slight rise in the basic locomotor activity which was significantly increased in the animals with inhibited monoamine oxidase activity. Besides that, they suppressed the behavior of rats in the open-field test, inhibited the conditioned avoidance response, decreased body temperature and increased amphetamine-induced motor hyperactivity. Noradrenaline, in contrast to dopamine, changed the intensity of amphetamine-induced stereotypy and prolonged the action of hypnotics. The central action of both catecholamines (in higher doses especially) seemed to have a biphasic course: in the first phase after administration depression was observed which was more pronounced after noradrenaline administration, in the second phase a stimulating effect b     

Adrenergic activation of the liberation of corticotropin-releasing hormone (CRH41) in the median eminence of unanesthetized rats

To shed light on the persistent controversy concerning the role of central adrenergic systems in the corticotropic axis, we measured the effects of adrenaline on the release of IR-rCRH41 into a push-pull cannula stereotaxically implanted in the median eminence. Eight days before experimentation, the cannula was implanted, under deep anesthesia, at which time a standard cannula was additionally placed in the lateral ventricle (i.c.v.). The rats were not anesthetized during the main experiment. An i.c.v. injection of 5 microliter of solvent only slightly affected the release of CRH41, whereas an i.c.v. infusion of 1.4 micrograms adrenaline bitartrate under the same conditions led to an instantaneous, but short-lived, 8-fold rise in the CRH41 release above baseline. The data provide the first demonstration of a central stimulatory effect of adrenaline on the secretory activity of CRH41 producing neurons, in unanesthetized, free-moving rats.     

Neurotensin inhibits LH release

The present studies were designed to assess the effect of neurotensin on the release of LH, FSH, and prolactin in long-term castrated female rats. The animals were implanted in the lateral ventricle of the brain wih a cannula to allow the administration of either neurotensin or the vehicle. The peptide (30 microgram, dissolved in saline) or the control saline solution was injected intraventricularly in a volume of 10 microliter following pentobarbital anesthesia. Blood samples were collected at sacrifice 15, 30 and 60 min after injection. A significant decrease of serum LH levels was already present in neurotensin-treated animals at 15 min, and was maintained up to the end of the experiment. This decrease was not accompanied by any change in FSH or prolactin secretion. The results suggest that this tridecapeptide participates in the control of LH release and provide new data on the separate control of the release of the two gonadotropins.     

Cellular uptake of intracerebroventricularly administered biotin- or digoxigenin-Labeled antisense oligodeoxynucleotides in the rat

Summary 1. Antisense oligodeoxynucleotides (ODNs) internally labeled with biotin or digoxigenin were injected into the lateral ventricle of rats and the distribution of the labeled ODNs was examined at several timepoints following the intracerebroventricular (icv) injections. The stability of these injected antisense ODNs, which had no backbone modifications, was also studied by performing recovery experiments.2. The most intense labeling was observed near the injection site, in periventricular areas, and in perivascular regions. Many of the labeled cells appeared to be neurons, and both the cytoplasm and the nuclei were stained. The labeled cells were detected 15 min after icv injection, demonstrating that the antisense ODNs were taken up rapidly by cells in the parenchyma. The digoxigeninated antisense ODNs were presented in both the cytoplasmic and the nuclear fractions of rat brain extracts, however, the levels appeared to be much lower in the nuclear fractions.3. Antisense ODNs injected into the lateral ventricle seemed to follow the bulk flow of cerebrospinal fluid (CSF), i.e., from the injection site in the lateral ventricle, through the ventricular system, to the subarachnoid spaces and the perivascular spaces. From the ventricular and perivascular spaces, the antisense ODNs diffused into the extracellular space and were taken up by cells. The full-length digoxigeninated antisense ODNs were detectable within cells after only 15 min, indicating their rapid uptake. In addition, the antisense ODNs appeared to be relatively stable in the brain since the full-length digoxigeninated ODNs were still detectable after 4 hr.     

GPER1 Modulates Synaptic Plasticity During the Development of Temporal Lobe Epilepsy in Rats

G-protein coupled estrogen receptor 1 (GPER1) is a novel type of estrogen receptor. Several studies have shown that it has an anti-inflammatory action,which plays an important role in remyelination and cognitive ability adjustment. However, whether it is involved in the development of temporal lobe epilepsy (TLE) is still unknown. The present study established a TLE model by intraperitoneal injection of lithium chloride (3 mmol/kg) and pilocarpine (50 mg/kg) in rats to study the effect of GPER1 in the synaptic plasticity during the development of temporal lobe epilepsy. A microinjection cannula was implanted into the lateral ventricle region of rats via a stereotaxic instrument. G-1 is the specific GPER1 agonist and G15 is the specific GPER1 antagonist. The G1 or G15 and Dimethyl sulfoxide were injected into the rat brains in the intervention groups and control group, respectively. After G1 intervention, the learning and memory abilities and hippocampal neuron damage in epileptic rats were significantly improved, while G15 weakened the neuroprotective effect of GPER1. Meanwhile, G1 controlled the abnormal formation of hippocampal mossy fiber sprouting caused by seizures, and participated in the regulation of synaptic plasticity by reducing the expression of Synapsin I and increasing the expression of gephyrin. Inhibitory synapse gephyrin may play a significant role in synaptic plasticity.

     

Central noradrenergic inhibition of gastric mucosal blood flow and acid secretion in rats

To investigate the role of central noradrenaline (NA) in gastric functions, changes in mucosal blood flow (MBF) and acid secretion following electrical stimulation of the lateral hypothalamic area (LHA) and the effects of NA on these parameters were examined in rats anesthetized with urethane. NA 10 μg/animal injected into the lateral ventricle decreased the basal value of both the gastric MBF and acid output, while the same dose of acetycholine or dopamine was without effect. Repetitive electrical stimulation of LHA at 10 cycles/sec, 0.5 mA, 2 msec for 10 min elicited a significant, reproducible increase in both gastric MBF and acid output. NA 10 μg/animal injected into the lateral ventricle completely blocked these increases induced by the electrical stimulation. These data suggest that a central noradrenergic inhibitory mechanism is involved in regulation of the gastric MBF and acid secretion.     

下丘脑外侧区注入胃泌素对大鼠胃酸分泌的影响

本工作观察了下丘脑外侧区(LHA)、腹内侧核(VMH)或侧脑室(LCV)注射17肽胃泌素(G17)或五肽胃泌素(G5)对清醒大鼠胃酸分泌的影响。结果表明,将 G17或 G5注入 LHA可引起胃酸分泌明显增加,而将 G5注入 VMH、LCV 或静脉则不影响胃酸分泌;切断迷走神经可以阻断在 LHA 注入 G5引起胃酸分泌增加的效应;在阿托品背景下,将 G5注入 LHA仍能引起胃酸分泌明显增加;静脉注射酚妥拉明,心得安或纳洛酮均不影响 G5对 LHA 刺激胃酸分泌的作用。这些结果提示:LHA 是胃泌素作用的一个特异性部位,由 LHA 发出的冲动可能通过迷走神经内的两种传出纤维引起胃酸分泌,一为胆碱能纤维,另一为非胆碱能非肾上腺素能纤维。     

胰岛素对AD模型大鼠空间学习记忆能力的影响

目的:探讨胰岛素对阿尔茨海默氏病(AD)模型大鼠学习记忆能力影响及其可能机制。方法:大鼠海马微量注射Okadaic acid(OA),胰岛素侧脑室注射。水迷宫实验检测大鼠学习记忆能力;Western blotting实验检测大鼠海马烟碱型胆碱能受体的表达;免疫组化观察大鼠脑内胶质纤维酸性蛋白(GFAP)的表达。结果:与对照组比较,模型组大鼠学习记忆能力明显下降(P<0.01),烟碱型胆碱能受体表达减少(P<0.05),GFAP免疫阳性星形胶质细胞增多(P<0.05)。与模型组相比,胰岛素组大鼠学习记忆能力明显提高(P<0.01),烟碱型胆碱能受体表达增多(P<0.05),GFAP免疫阳性星形胶质细胞减少(P<0.05)。结论:胰岛素提高AD模型大鼠的学习记忆能力可能与其改善模型鼠胆碱能系统功能及减少星形胶质细胞增生有关。     

Behavioral activation by CRF: evidence for the involvement of the ventral forebrain

Rats injected intracerebroventricularly with corticotropin releasing factor (CRF) at the level of the lateral ventricle or cisterna magna showed a dose-dependent increase in locomotor activity. The increase in locomotor activity from injections of CRF into the cisterna magna was blocked by a cold cream plug in the cerebral aqueduct. An identical plug failed to block the increase in locomotor activity produced by CRF injected into the lateral ventricle. Intracerebral injections of CRF produced a site specific increase in locomotor activity with the largest increases observed from CRF injected into the substantia innominata/lateral preoptic area. Results suggest that the locomotor activating effects of CRF may be due to an activation of CRF receptors in the ventral forebrain, a region rich in CRF cell bodies and projections.     

Angiotensin II Synthesis Studies in Dissociated Brain Cell Cultures

Abstract: The biosynthesis of angiotensin II-like peptide was measured in primary cultured brain cells from the fetal rat. Cells from the whole brains of 20-day gestational age Sprague-Dawley rats were dissociated by mild trypsinization and grown for 5 days in supplemented (serum-free) medium prior to experimental analysis. The time-dependent incorporation of [³H]proline into newly synthesized angiotensin II-like peptide was measured by radioimmunoassay using specific angiotensin II antisera. Analysis of radioimmunoassay data revealed an increase in the amount of tritium-labeled angiotensin II in the crude extract of the brain cells during the first 24 h in culture. The chromatographic character of the angiotensin II-like peptide was further identified by high pressure liquid chromatography. Elution profiles for newly synthesized angiotensin II were identical to those profiles generated for [³H]angiotensin II and nonradiolabeled angiotensin II standards. To determine the bioactivity of the angiotensin II-like peptide, fractions of the column-purified peptide were injected into the region of the rat lateral ventricle via an indwelling cannula. Systolic pressure increased up to 20 mm Hg depending upon the amount of peptide injected. These data clearly support the existence of an endogenous renin-angiotensin system in dissociated brain cell cultures from the fetal rat, and provide an experimental model for further analysis of the regulatory mechanisms of angiotensin II synthesis.