The distribution of PGP9. 5, BDNF and NGF in the vallate papilla of adult and developing mice

The development and innervation of vallate papillae and taste buds in mice were studied using antibodies against the neuronal marker, protein gene product 9.5 (PGP 9.5), and against nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). PGP 9.5 immunohistochemical studies revealed that the earliest sign of median vallate papilla formation was an epithelial bulge at embryonic day 13 (E13), and at E14, a dense nerve plexus was found within the connective tissue core of the papilla. Thin nerve fibers penetrated the apical and medial trench wall epithelium of the papilla at E16 and a few of these began to invade the lateral trench wall epithelium at E17. At postnatal day 1 (P1), the newly formed taste buds were recognizable and a small number of PGP 9.5-immunoreactive (IR) cells appeared on the medial trench wall epithelium. The number of PGP 9.5-IR taste bud cells then increased gradually and reached the adult level at postnatal week 2. PGP 9.5 immunoreactivity increased systematically with age. NGF and BDNF immunoreactivity was first seen at the boundary between the columnar cells in the apical epithelium of the developing vallate papilla at E13, then in the medial and lateral trench walls at E15 (BDNF) or E18 (NGF). At P1, BDNF immunoreactivity was exclusively present in the newly formed taste buds of the medial trench wall. The number of BDNF-IR taste bud cells then increased gradually, reaching the adult level at P7. Similar degrees of NGF and BDNF immunoreactivity were seen in the developing vallate papilla. In the present study, we found that the vallate papilla was formed prior to its innervation, and we propose that initiation of papilla formation does not require any direct influence from the specific gustatory nerve. We also suggest that neurotrophins in the early developing vallate papillae might act as local tropic factors for the embryonic growth of nerve fibers to induce differentiation of the taste buds.     

Tuberoinfundibular peptide of 39 residues in the embryonic and early postnatal rat brain

Tuberoinfundibular peptide of 39 residues (TIP39) was identified as the endogenous ligand of parathyroid hormone 2 receptor. We have recently demonstrated that TIP39 expression in adult rat brain is confined to the subparafascicular area of the thalamus with a few cells extending laterally into the posterior intralaminar thalamic nucleus (PIL), and the medial paralemniscal nucleus (MPL) in the lateral pontomesencephalic tegmentum. During postnatal development, TIP39 expression increases until postnatal day 33 (PND-33), then decreases, and almost completely disappears by PND-125. Here, we report the expression of TIP39 during early brain development. TIP39-immunoreactive (TIP39-ir) neurons in the subparafascicular area first appeared at PND-1. In contrast, TIP39-ir neurons were detectable in the MPL at embryonic day 14.5 (ED-14.5), and the intensity of their labeling increased thereafter. We also identified TIP39-ir neurons between ED-16.5 and PND-5 in two additional brain areas, the PIL and the amygdalo-hippocampal transitional zone (AHi). We confirmed the specificity of TIP39 immunolabeling by demonstrating TIP39 mRNA using in situ hybridization histochemistry. In the PIL, TIP39 neurons are located medial to the CGRP group as demonstrated by double immunolabeling. All TIP39-ir neurons in the AHi and most TIP39-ir neurons in the PIL disappear during early postnatal development. The adult pattern of TIP39-ir fibers emerge during postnatal development. However, fibers emanating from PIL can be followed in the supraoptic decussations towards the hypothalamus at ED-18.5. These TIP39-ir fibers disappear by PND-1. The complex pattern of TIP39 expression during early brain development suggests the involvement of TIP39 in transient functions during ontogeny.     

Developmental changes of glutamate receptors in the rat cerebral cortex and hippocampus

We studied the immunohistochemial localization of the glutamate receptors (GluR-1, -2, and -3,) in the developing rat cerebral cortex and hippocampus using antibodies to GluR1 and to an epitope common to GluR2 and GluR3 (GluR2/3) subunits. In the cerebral cortex, GluR1 immunoreactivity appeared in the neurons from postnatal day (PND) 0, increased with maturation, was highest at PND?10, decreased until PND 30, and thereafter remained at the same level as on PND?0. GluR2/3 immunoreactivity appeared earlier in scattered neurons on embryonal day (ED) 18, increased with maturation and reached a peak between PND?10 and PND?15, after which the immunoreactivity gradually decreased and reached a plateau at PND?30. For both GluR1 and GluR2/3, some of the pyramidal neurons showed intense staining. In the pyramidal layers of the hippocampus, GluR1 and GluR2/3 immunoreactivity was found in all the pyramidal neurons of the CA1–4 area from ED?20. In the dentate gyrus of the hippocampus, GluR1 and GluR2/3 immunoreactivity was found in the neurons of the granule cells after PND?0. Immunoreactivity in the neurons of the subiculum was found after PND?5 and that of the polymorphic cell layers was found after PND?15–20. Our results indicate that the development of glutamate receptor subunits in the rat cerebral cortex and hippocampus is expressed in different spatial patterns and distinct temporal patterns throughout development and is scheduled during the early postnatal period, when synaptic plasticity or synaptic connection occurs in these regions.     

Expression of BDNF and TrkB in mouse taste buds after denervation and in circumvallate papillae during development

BDNF (brain-derived neurotrophic factor) is a member of the neurotrophin family which affects the proliferation and survival of neurons. Using an immunocytochemical method, we examined the expression of BDNF and its receptor, TrkB, in the taste bud cells of the circumvallate papillae of normal mice and of mice after transection of the glossopharyngeal nerves. We additionally observed the expression of BDNF and TrkB in the developing circumvallate papillae of late prenatal and early postnatal mice. In normal untreated mice, BDNF was expressed in most of the taste bud cells; TrkB was detected in the plasma membrane of taste bud cells and in the nerve fibers. Double-labeling studies showed that BDNF and NCAM (neural cell adhesion molecule) or TrkB and NCAM colocalized in some of the taste bud cells, but that most taste bud cells were immunopositive for only BDNF or TrkB. NCAM-immunoreactive cells are known to be type-III cells, which have afferent synaptic contacts with the nerve terminals. Five days after denervation, the number of taste buds and nerve fibers markedly decreased; however, the remaining taste bud cells still expressed BDNF and TrkB. By 10 days after denervation, most of the taste buds had disappeared, and there were a few TrkB-immunoreactive nerve fibers in the connective tissue core. By 4 weeks after denervation, numerous TrkB-immunoreactive nerve fibers had invaded the papillae, and a few taste buds expressing BDNF and TrkB had regenerated. At E (embryonic day) 15 during development, the circumvallate papillae appeared, and then TrkB-immunoreactive nerve fibers entered the connective tissue core, and some of these fibers further invaded among the dorsal epithelial cells of the papillae. TrkB-immunoreactive oval-shaped cells were occasionally found in the dorsal epithelium. Such TrkB-immunoreactive nerve fibers and cells were also observed at E16-18. However, BDNF was not expressed in the papillae through the late prenatal days of E15 to E18. At P (postnatal day) 0, a cluster of BDNF-and TrkB-immunoreactive cells appeared in the dorsal epithelium of the papillae, and was presumed to be primitive taste buds. We conclude that TrkB-immunoreactive nerve fibers are necessary for papillary and taste bud formation during development and for the regeneration of taste buds after denervation. BDNF in the taste bud cells may act as a neurotrophic factor for innervating sensory neurons--through TrkB receptors of the axons of those neurons, and also may exert autocrine and paracrine trophic actions on neighboring taste bud cells by binding to their TrkB receptors.     

脑源性神经营养因子在大鼠海马CA3区发育过程中的表达

采用免疫组织化学ＡＢＣ 法,研究脑源性神经营养因子在大鼠海马ＣＡ３ 区发育过程中的表达,观察其免疫反应产物的分布。结果表明：脑源性神经营养因子阳性物质在生后零天（Ｐ０）组位于ＣＡ３ 区细胞周围间质内;Ｐ１０,Ｐ１５ 和Ｐ２０ 组脑源性神经营养因子免疫反应产物位于锥体细胞内,幅射层内可见阳性苔藓纤维终末,这些终末随生后日龄增加而增加。Ｐ３０ 组脑源性神经营养因子免疫反应产物仅见于细胞周围间质内,未见细胞胞浆内有阳性物质分布,但偶见脑源性神经营养因子阳性细胞核位于ＣＡ３ 区锥体细胞层,辐射层内有较多的苔藓纤维阳性终末。本研究结果提示,发育早期大鼠海马ＣＡ３ 区脑源性神经营养因子分布于细胞周围间质而生后１０ 至２０ 天发育期间,ＣＡ３ 区锥体细胞合成脑源性神经营养因子并可沿神经元轴突顺行运输、传递信息。     

Ontogeny of the calcitonin gene-related peptide in the nervous system of rat brain stem: an immunohistochemical analysis

The ontogeny of the calcitonin gene-related peptide in the neuron system of the rat brain stem was investigated by means of the indirect immunofluorescence technique. Calcitonin gene-related peptide-like immunoreactivity was first detected in the fibers of the nucleus of spinal tract trigeminal nerve on gestational day 18, and thereafter appeared gradually in various brain stem areas such as in the fibers of the solitary tract, gracile nucleus, cuneate nucleus, inferior colliculus, superior colliculus, medial geniculate nucleus and in the neurons of the hypoglossal nucleus, facial nucleus, superior olive, parabrachial area, superior colliculus and peripeduncular nucleus. In colchicine-untreated animals, the immunoreactive fibers increased in number and reached adult level by postnatal day 14, whereas the number of cells reached a maximum between postnatal days 2 and 6 and then decreased in number and immunoreactivity or disappeared, except in some areas such as the superior olive and peripeduncular nucleus, which showed the same immunoreactivity as for adult animals. With colchicine treatment, calcitonin gene-related peptide-like immunoreactive cells were found in more areas of the brain stem such as the abducens nucleus, parabigeminal nucleus, principal oculomotor nucleus, trochlear nucleus and central gray, along with the nuclei which had shown calcitonin gene-related peptide immunoreactivity in the untreated animals. However, the neurons in the inferior olive showed a different ontogenetical pattern of calcitonin gene-related peptide of immunoreactivity. Immunoreactivity disappeared completely by postnatal day 21 in both colchicine-untreated and -treated animals.     

大鼠海马CA1和CA3区发育过程中酪氨酸激酶受体B的分布

为了观察脑源性神经营养因子的特异性受体—酪氨酸激酶受体 B在发育过程中的大鼠海马 CA1和 CA3区的分布 ,本研究使用免疫组织化学 A BC法研究了生后几个时间段的酪氨酸激酶受体 B的分布特点。结果表明 :其免疫阳性产物仅出现在神经元胞体中且只位于胞浆 ,胶质细胞中未见分布。生后零天组偶见免疫阳性细胞 ;生后 5天组免疫阳性细胞较生后 0天组明显增多 ,但分布也尚较少 ;生后 10、15、2 0、30天 4组免疫阳性细胞呈明显的逐渐增多趋势。成年组的免疫阳性细胞与生后 30天组无明显差别。本实验结果提示 :发育早期大鼠海马 CA1和 CA 3区锥体细胞产生酪氨酸激酶受体 B,并通过对它的分泌调节 ,控制脑源性神经营养因子对神经元的作用 (突触的发生、发育、维持及神经元损伤后修复等     

Hypoxia-induced modification of poly (ADP-ribose) polymerase and dna polymerase beta activity in cerebral cortical nuclei of newborn piglets: role of nitric oxide

This study aimed to investigate whether continuous, low-dose, intracerebral infusion of either brain-derived neurotrophic factor (BDNF) or neurotrophin-3 (NT-3) could protect against striatal neuronal loss in mild neonatal hypoxic/ischaemic brain injury. Continuous, low-dose, intracerebral treatment is likely to minimise unwanted side effects of a single high dose and lengthen the time window for neuroprotection. A milder, albeit brain damage-inducing, hypoxic/ischaemic injury paradigm was used since this situation is likely to produce the highest survival rates and thus the greatest prevalence. Anaesthetised postnatal day 7 rats were each stereotaxically implanted with a brain infusion kit connected to a micro-osmotic pump. The pump continuously infused either BDNF (4.5 microg/day), NT-3 (12 microg/day), or vehicle solution into the right striatum for 3 days from postnatal day 7. The intrastriatal presence of BDNF or NT-3 was verified immunohistochemically. On postnatal day 8, the rats underwent right common carotid artery ligation followed by hypoxic exposure for 1.5 h. Animals were weighed daily thereafter and killed 1 week later on postnatal day 14. The total number of medium spiny neurons within the right striatum was stereologically determined using an optical disector/Cavalieri combination. Other measures of neuroprotection such as brain weight and striatal infarct volume were also undertaken. BDNF or NT-3 significantly increased the total number of surviving medium spiny neurons by 43% and 33% respectively. This significant neuroprotection was not evident when brain weight, striatal volume, striatal infarct volume, and neuronal density measures for NT-3, were compared. These measures therefore missed the protective effect demonstrated by the total neuronal count. This suggests that stereological measurement of total neuronal number is needed to detect neuroprotection at 1 week after low-dose, continuously infused, neurotrophin treatment and mild hypoxic/ischaemic injury. The results also suggest that lower treatment doses may be more useful than previously thought. BDNF may be particularly useful since it fostered both neuroprotection and normal weight gain. The ability to rescue striatal neurons from death may contribute toward a potential short-term, low-dose neurotrophin treatment for mild perinatal hypoxic/ischaemic brain injury in humans.     

出生前后胆碱乙酰转移酶在大鼠脑内定位的研究

为探讨大鼠胚胎及生后发育期间脑内胆碱乙酰转移酶(choline acetyltransferase,ChAT)的变化规律,本研究采用免疫组织化学方法,观察了胚胎和生后大鼠脑内ChAT样(ChAT-like immunoreactive,ChAT-LI)神经元表达的数量和灰度值。结果显示:ChAT-LI产物主要表达在细胞体、纤维及其末梢。ChAT-LI神经元最先在胚胎第12d(embryonic day12,E12),出现于端脑;E14时可见于隔核和中缝核;E16时内嗅区出现ChAT-LI神经元;E18时出现于视前区节细胞层;E20时,海马内部可见部分ChAT-LI纤维;生后第0d(postnatal day0,P0),少量带有生长锥的ChAT-LI纤维出现于海马;P5时,海马内出现ChAT-LI神经元,且ChAT-LI纤维进一步增加;P10时,海马、内嗅区和穹隆等结构中都可见ChAT-LI神经元胞体及纤维。上述结果提示:胆碱能神经元在出生前后的大鼠脑内,尤其是在海马记忆回路的发育过程中存在一定的变化规律,它们可能是学习记忆等功能的结构基础。     

促肾上腺皮质激素对慢性痛大鼠痛行为和海马内BDNF、CRF水平的影响

目的与方法:采用痛行为评分方法、免疫组化和原位杂交技术,观察促肾上腺皮质激素(ACTH)对完全福氏佐剂所致的关节炎大鼠海马内脑源性神经营养因子(BDNF)及其功能性受体trkB和促肾上腺皮质激素释放激素(CRH)水平的影响。结果:关节炎大鼠的痛行为评分显著高于正常对照组,同时注射侧对侧海马内BDNF免疫活性(IR)神经元、CRHmRNA阳性神经元和BDNF/CRHmRNA双染神经元数在注射佐剂后 2 4h显著高于正常对照组,而腹腔注射ACTH(2 5IU/kg或 12 5IU/kg)后,上述指标显著低于关节炎组;摘除双侧肾上腺后,腹腔注射ACTH的关节炎大鼠对侧海马内BDNF-IR、CRHmRNA阳性神经元和BDNF/CRHmRNA双染神经元数明显高于未摘除肾上腺的关节炎组。结论:海马内的BDNF和CRH参与慢性痛的调制,ACTH能抑制海马内BDNF和CRH的升高而产生镇痛作用,肾上腺对ACTH发挥其功能起决定性作用.     

Developmental changes of glutamate receptors in the rat cerebral cortex and hippocampus

 We studied the immunohistochemial localization of the glutamate receptors (GluR-1, -2, and -3,) in the developing rat cerebral cortex and hippocampus using antibodies to GluR1 and to an epitope common to GluR2 and GluR3 (GluR2/3) subunits. In the cerebral cortex, GluR1 immunoreactivity appeared in the neurons from postnatal day (PND) 0, increased with maturation, was highest at PND 10, decreased until PND 30, and thereafter remained at the same level as on PND 0. GluR2/3 immunoreactivity appeared earlier in scattered neurons on embryonal day (ED) 18, increased with maturation and reached a peak between PND 10 and PND 15, after which the immunoreactivity gradually decreased and reached a plateau at PND 30. For both GluR1 and GluR2/3, some of the pyramidal neurons showed intense staining. In the pyramidal layers of the hippocampus, GluR1 and GluR2/3 immunoreactivity was found in all the pyramidal neurons of the CA1–4 area from ED 20. In the dentate gyrus of the hippocampus, GluR1 and GluR2/3 immunoreactivity was found in the neurons of the granule cells after PND 0. Immunoreactivity in the neurons of the subiculum was found after PND 5 and that of the polymorphic cell layers was found after PND 15–20. Our results indicate that the development of glutamate receptor subunits in the rat cerebral cortex and hippocampus is expressed in different spatial patterns and distinct temporal patterns throughout development and is scheduled during the early postnatal period, when synaptic plasticity or synaptic connection occurs in these regions. Accepted: 13 June 1996     

NGF,BDNF,NT-3和GDNF在背根节不同神经元的配布的免疫组织化学证据

为了探讨神经生长因子、脑源性神经生长因子 ,神经营养素 -3,胶原细胞源性神经生长因子在成年猫背根节神经元不同大小细胞的分布。取 L6背根节制成 2 0μm厚冰冻切片 ,用上述四种因子抗血清进行免疫组化反应。计数每一种因子阳性大、中、小型 (小于 42μm者为小型神经元 ;42～ 5 7μm者为中型神经元 ;大于 5 7μm者为大型神经元 )神经元的百分数。结果证明 ,此四种因子在背根节大、中、小神经元的阳性百分数分别为 :1.2± 0 .7,2 .1± 0 .9,3.3± 1.1;1.7± 0 .4,11.2± 1.2 ,30 .0± 1.5 ;2 6 .7± 2 .2 ,6 .2± 1.2 ,13.2± 2 .9;2 7.4± 3.3,8.1± 1.7,2 0 .1± 2 .4。表明 :在成年猫 L6背根节仅存在少数神经生长因子阳性细胞 ,而脑源性神经生长因子则主要配布于中、小神经元 ,神经营养素 -3和胶质细胞源性生长因子的免疫阳性细胞主要是大神经元 ,但也包括一些中小神经元。提示此四种因子在成年猫背根节的生理功能可能与神经元的不同大小有关。     

Differential neurotrophin levels in cerebrospinal fluid and their changes during development in newborn rat

Cerebrospinal fluid concentration of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) was measured in normal developing rat from birth to postnatal day (PND) 21 by enzyme-linked immunosorbent assay. NGF levels were significantly higher than those of BDNF and NT-3 from PND 1–21. NGF levels decreased from PND 1–3 to PND 9. At PND 15 and 17, NGF levels peaked a second time and rapidly decreased to PND 21. BDNF peaked at PND 13–15, while NT-3 levels peaked at PND 7–9. Each of the three neurotrophins has its own characteristic pattern in changes in cerebrospinal fluid levels.     

Early maternal deprivation induces alterations in brain-derived neurotrophic factor expression in the developing rat hippocampus

The effects of maternal deprivation (MD) during early postnatal life on the brain-derived neurotrophic factor (BDNF) level were investigated in the present study. Wistar rats were assigned to either maternal deprivation or mother-reared control (MRC) groups. MD manipulation was achieved by separating rat pups from their mothers for 3h a day during postnatal days (PND) 10-15. At 16, 20, 30, and 60 days of age, the level of BDNF mRNA in the hippocampal formation of each group was determined using real-time PCR analysis. Early postnatal maternal deprivation of rat pups resulted in a significant increase in body weight at 60 days of age. The expression of BDNF mRNA in the hippocampus was significantly decreased at 16 days of age, and increased at 30 and 60 days of age. These data indicate that even a brief period of maternal deprivation during early postnatal life can affect hippocampal BDNF expression.     

人参环氧炔醇对体外培养施万细胞表达神经营养因子的影响及可能机制的研究

目的 研究人参环氧炔醇(PND)对体外培养施万细胞(SCs)神经营养因子(NTFs)表达的影响;并探讨其机制.方法 用含有不同浓度的PND培养液分别处理SCs,以免疫组织化学法检测PND对SCs NTFs表达的影响;放射免疫方法测定SOs内环磷酸腺苷(cAMP)水平的变化,并进行图像处理及统计学分析.结果 PND分别在2.5～20.0μmol/L及5.0～20.0μmol/L剂量范围内可分别促进体外培养SCs NGF及大脑衍生神经营养因子(BDNF) 的表达(P<0.05),在10μmol/L剂量对两者促进作用均最明显(P<0.01);在2.5～20.0μmol/L剂量范围内PND可提高体外培养SCs胞内cAMP含量(P<0.05),而在10μmol/L剂量作用最显著(P<0.01).结论 PND能明显促进体外培养SCs NGF、BDNF的表达和分泌;PND可提高SCs的胞内cAMP水平,并与PND促进体外培养SCs NGF、BDNF 表达之间存在相关性,提示其可能是PND提高体外培养SCs NGF、BDNF表达的调控机制及信号传导通路.     

BDNF、NGF对AD模型鼠脑移植区一氧化氮合酶阳性神经元发育生长的影响

用使君子酸（ＱＡ）损毁ＳＤ 大鼠左侧Ｍ ｅｙｎｅｒｔ基底大细胞核,制成老年性痴呆症（ＡＤ）模型。将同种鼠胚基底前脑制成的细胞悬液不加神经营养因子和分别加入脑源性神经营养因子（ＢＤＮＦ）、神经生长因子（ＮＧＦ）及ＢＤＮＦ＋ ＮＧＦ者植入ＡＤ 模型鼠额、顶叶皮质,隔日通过脑室灌注人工脑脊液和相应神经营养因子共７ 次。移植后４ 个月,取脑切片作Ｎｉｓｓｌ染色、ＮＡＤＰＨ ｄ和ＮＡＤＰＨ ｄ＋ ＡＣｈＥ 组化染色,计数移植区中ＮＯＳ阳性神经元数及其纤维在１６９００ μｍ ２ 网格中的交点数,并用ＭＩＡＳ ３００ 计算机图像分析系统对移植区中ＮＯＳ阳性神经元的细胞面积进行处理。结果显示：给予神经营养因子的动物,移植区中的ＮＯＳ阳性神经元数、ＮＯＳ阳性纤维交点数和ＮＯＳ阳性神经元的细胞面积等形态学指标均较不给予神经营养因子的对照组为佳,而在应用神经营养因子的各组中又以ＢＤＮＦ＋ ＮＧＦ组为优,提示ＢＤＮＦ、ＮＧＦ能促进移植区中ＮＯＳ阳性神经元的发育生长,ＢＤＮＦ与ＮＧＦ联合使用可发挥协同作用。本文对ＢＤＮＦ和ＮＧＦ促进移植区中ＮＯＳ阳性神经元发育生长的机制进行了探讨。     

Morphometric analysis of the developing rat brain

In 2 studies, a method of linear morphometry was applied to regulatory developmental neurotoxicity studies in the rat. The first study involved the development of the brain during postnatal days (PNDs) 7-63, and the second involved the effects of 8 mg/kg i.p. trimethyltin chloride (TMT) to rats at PND 8, with morphometry performed at PNDs 12 and 24. The results of the TMT linear morphometry were compared with those from stereologic counting of neurons in the cerebral cortex, piriform cortex, and hippocampus. Stereology produces more meaningful data than simple linear morphometry for use in the regulatory assessment of the developmental neurotoxicity potential of compounds.     

Development of the norepinephrine transporter in the rat CNS

The norepinephrine transporter (NET) plays a major role in regulating the actions of norepinephrine by removing norepinephrine from the synapse. Many studies suggest norepinephrine plays an important role in regulating development of the CNS, pointing to NET as an important factor in this process. We examined the ontogeny of NET expression in rat brain at 5, 10, 15, 20 and 25 days postnatally (PND) and in adults, using quantitative autoradiography with [3H]nisoxetine as ligand. At PND 5 and 10 most forebrain areas had low NET expression (1-2 fmol/mg tissue). By PND 15 most forebrain areas increased NET expression approximately five-fold compared with PND 10, levels generally similar to those found in the adult brain. In contrast, NET development in the brainstem exhibited elevated densities at PND 5, 10 and 20 that decreased in the adult. The locus coeruleus, in particular, had very high NET expression in the early postnatal period that decreased dramatically in the adult brain. These data illustrate a dynamic ontogenic profile for NET, characterized by developmental increases in forebrain structures and contrasting decreases in the brainstem. The early postnatal expression of NET in brainstem and the subsequent decrease or loss of NET expression with maturation suggest an important role for this transporter and for norepinephrine in the development of many brain regions. These studies also have important implications for use of drugs targeting the noradrenergic system in children and adolescents, such as antidepressants and drugs of abuse.     

Ontogeny of cholecystokinin-8 containing neuron system of the rat: An immunohistochemical analysis—II. Lower brain stem

The ontogeny of the cholecystokinin-8 neuron system in the lower brain stem of the rat was investigated by means of indirect immunofluorescence. Cholecystokinin-8-like immunoreactive structures first appeared in the primordium of the ventral tegmental area, ventral tegmental nucleus of Gudden and the area lateral to the superior central nucleus of the fetus on gestational day 17. Although cholecystokinin-8-like immunoreactive structures appeared gradually in various lower brain stem areas from this day, and developed markedly from postnatal day 6, thereafter, the ontogeny of cells and fibers was different. In general, the fibers increased in number as the rats grew and reached the maximum in adulthood, whereas the cells reached a maximum number between postnatal days 6–12, after which they decreased in number. Colchicine treatment, however, demonstrated the presence of cholecystokinin-8-like immunoreactive cells in various areas of the lower brain stem.

These findings suggest that the cholecystokinin-containing neuron system is active in the adult and that cholecystokinin-containing cell somata cannot store a sufficient amount of the peptide for visualization in the absence of colchicine. Thus, it might be concluded that cholecystokinin may play an important role in the brain function of the adult as a neurotransmitter or neuromodulator, though its exact function is now open to discussion.     

Early induction of neuronal lipocalin-type prostaglandin D synthase after hypoxic-ischemic injury in developing brains

Lipocalin-type prostaglandin (PG) D synthase (L-PGDS) is up-regulated in oligodendrocytes (OLs) in mouse models for genetic neurological disorders including globoid cell leukodystrophy (twitcher) and GM₁ and GM₂ gangliosidoses and in the brain of patients with multiple sclerosis. Since L-PGDS-deficient twitcher mice undergo extensive neuronal death, we concluded that L-PGDS functions protectively against neuronal degeneration. In this study, we investigated whether L-PGDS is also up-regulated in acute and massive brain injury resulting from neonatal hypoxic-ischemic encephalopathy (HIE). Analysis of brains from human neonates who had died from HIE disclosed that the surviving neurons in the infarcted lesions expressed L-PGDS. Mouse models for neonatal HIE were made on postnatal day (PND) 7. Global infarction in the ipsilateral hemisphere was evident at 24 h after reoxygenation in this model. Intense L-PGDS immunoreactivity was already observed at 10 min after reoxygenation in apparently normal neurons in the cortex, and thereafter, in neurons adjacent to the infarcted area. Quantitative RT-PCR revealed that the L-PGDS mRNA level of the infarcted hemisphere was 33-fold higher than that of the sham-operated mouse brains at 1 h after reoxygenation and that it decreased to the normal level by 24 h thereafter. Furthermore, in both human and mouse brains, many of L-PGDS-positive cells were also immunoreactive for p53; and some of these expressed cleaved caspase-3. The expression of L-PGDS in degenerating neurons implies that L-PGDS functions as an early stress protein to protect against neuronal death in the HIE brain.