Colocalization of parvalbumin, calretinin and calbindin D-28k in human cortical and subcortical visual structures

Several studies have demonstrated that three calcium-binding proteins parvalbumin (PV), calbindin D-28k (CB) and calretinin (CR) mark distinct subsets of cortical interneurons. This study demonstrates, in cortical and subcortical visual structures, the coexistence of two calcium-binding proteins in some neuronal subpopulations. The human visual cortex (VC), lateral geniculate nucleus (LGN), lateral inferior pulvinar (LIP) and superior colliculus (SC) were examined by a double-labelling immunocytochemical technique. The VC showed mostly separate populations of PV, CB and CR immunoreactive (-ir) interneurons, but also small populations of double-stained PV+CR and CR+CB neurons, while PV+CB neurons were less frequent. An average of 2.5% of the immunoreactive neurons were double-stained for PV+CR and 7.1% for CR+CB in area 17, while this percentage was slightly higher in association area 18 (3.3 and 7.4%, respectively). In the LGN and LIP, double-stained neurons were scarce, but in the fibre capsule of these nuclei, as well as in the optic radiation (OR) and white matter underlying area 17, both double-stained PV+CR or CR+CB and separate populations of PV-ir, CB-ir and CR-ir neurons and fibres were observed. Unlike the thalamic regions, the SC showed some double-stained PV+CR and CR+CB neurons, scattered both in the superficial and deep layers. These findings are discussed in the light of similar observations recently reported from other regions of the human brain.     

Calbindin D28k and parvalbumin immunoreactivity in the rabbit superior colliculus: an anatomical study

The expression pattern of two calcium binding proteins (CaBP), calbindin D28k (CB) and parvalbumin (PV), in the superior colliculus (SC) of the adult rabbit, as well as the morphology of the immunoreactive cells were examined. The study was performed on 12 rabbits. Coronal sections from postmortem SC were analyzed by light microscopy, and drawings of CaBP-labeled cells were obtained using a drawing tube. No previous information is available on either the CB/PV expression or the morphology of CB/PV positive cells in the SC of the adult rabbit. Therefore, in this study we show that CB neurons and neuropil form three main tiers: the first located within the stratum zonale (SZ) and the upper part of the stratum griseum superficiale (SGS), the second located within the stratum griseum intermedium (SGI), and the third, located within the medial and central areas of the stratum griseum profundum (SGP). In contrast to this layer labeling, almost no CB-positivity is found within the other collicular layers. On the other hand, the densest concentration of PV labeled cells and terminals is found within a single dense tier that spanned the ventral part of the startum griseum superficiale (SGS) and the dorsal part of the stratum opticum (SO). Anti-PV neurons are also scattered through the deeper layers below the dense tier. In contrast, almost no anti-PV labeled neurons or neuropil are found within the stratum zonale (SZ) and upper SGS. This distribution represents a new pattern of sublamination in the SC of this species. All the previously described cell types in other mammals are observed in the rabbit SC: marginal cells, horizontal cells, pyriform cells, narrow-field vertical cells, wide-field vertical cells, and stellate/multipolar cells. Detailed drawings of all these cellular types are represented to show their complete morphology. The results of this study indicate that both CB and PV are present in a variety of neurons, which present a number of homologies between mammals, but have a different location and/or distribution, according to the different species. These findings are thus relevant to better understand the organisation of the SC in mammals.     

胸腺及其投射神经元一氧化氮的分布

本实验用 NADPH-d组织化学方法及 n NOS免疫细胞化学方法 ,对大鼠胸腺内一氧化氮 (NO)阳性细胞的分布进行了研究。采用 CB-HRP逆行追踪结合 n NOS免疫细胞化学双重反应技术 ,观察了大鼠胸腺投射神经元 n NOS的分布。结果显示 :(1)在脑干的疑核、面后核内有 CB-HRP与 n NOS双重阳性细胞 ;(2 )在胸腺内有多种 NADPH-d和 n NOS阳性细胞 ,按其形态可分为 :髓质上皮样细胞、胸腺树突样细胞、神经元样细胞、胸腺细胞样细胞及胸腺小体 ;(3 )在胸腺的被膜下、小梁内、皮髓质交界处、小血管的周围有丰富的 n NOS阳性纤维。提示 ,胸腺内 NO的来源不同 ,其在调节胸腺的各种活动中可能发挥的作用也不同     

Nitric oxide synthase distribution in the cat superior colliculus and co-localization with choline acetyltransferase

Nitric oxide and acetylcholine are important neuromodulators implicated in brain plasticity and disease. We have examined the cellular and fiber localization of nitric oxide in the cat superior colliculus (SC) and its degree of co-localization with ACh using nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry and an antibody to neuronal nitric oxide synthase. ACh was localized using an antibody against choline acetyltransferase. We also made injections of biocytin into the region of the parabrachial brainstem to confirm that this region is a source of nitric oxide containing fibers in SC. NADPHd labeled neurons within the superficial layers of the superior colliculus included pyriform, vertical fusiform, and horizontal morphologies. Labeled neurons in the intermediate gray layer were small to medium in size, and mostly of stellate morphology. Neurons in the deepest layers had mostly vertical or stellate morphologies. NADPHd labeled fibers formed dense patches of terminal boutons within the intermediate gray layer and streams of fibers within the deepest layers of SC. Choline acetyltransferase antibody labeling in adjacent sections indicated that many fibers must contain both labels. Over 94% of neurons in the pedunculopontine tegmental and lateral dorsal tegmental nuclei were also labeled by both NADPHd and choline acetyltransferase. In addition, biocytin labeled fibers from this region were localized in the NADPHd labeled patches. We conclude that nitric oxide is contained in a variety of cell types in SC and that both nitric oxide and ACh likely serve as co-modulators in this midbrain structure.     

单眼缝合、双眼缝合对猫视觉中枢中一氧化氮合酶阳性神经元数量与形态的影响

用ＮＡＤＰＨ－ｄ 组织化学方法观察了在生后一周内即施行单眼缝合和双眼缝合成活至１ 年的猫视觉中枢（上丘表层,外膝体和视皮层１７ 区）中的一氧化氮合酶阳性神经元数量及形态。结果显示：（１）单眼缝合或双眼缝合并不改变上丘表层中一氧化氮合酶阳性细胞的分布模式,也不影响该神经元的数量,但单眼缝合使对侧上丘表层一氧化氮合酶阳性神经元的树突野最大半径减小,树突总长度减少;而双眼缝合可使双侧上丘中一氧化氮合酶阳性细胞胞体减少,树突野最大半径以及树突总长度均明显减少。（２）单眼缝合导致外膝体非剥夺层中出现较多一氧化氮合酶阳性细胞,剥夺层少量出现,而双眼缝合却没有以上效应。（３）单眼缝合不影响视皮层１７ 区中一氧化氮合酶阳性细胞的空间分布模式以及该神经元在皮层各层中的分布密度;双眼缝合也不影响该神经元的分布模式,但可使ＮＡＤＰＨ－ｄ 黄递酶活性明显降低。提示视觉神经中枢中的一氧化氮合酶阳性神经元的活动受视网膜活动依赖性的调节,且受视觉经验的影响。     

一氧化氮合酶阳性神经元在小鼠脑内的分布

目的 :研究一氧化氮合酶 (NOS)在小鼠脑内的分布。方法 :用NADPH 黄递酶组织化学技术 ,观察了NOS阳性神经元在小鼠脑内的分布和形态。结果 :在大脑皮质、纹状体、基底前脑、杏仁核、下丘脑和脑干等处有较多一氧化氮合酶阳性神经元的分布。结论 :表明NO与中枢神经系统的诸多功能有关     

PDGFR-β基因敲除小鼠上丘内Otx2和PV免疫反应阳性神经元的分布

目的:探讨血小板源性生长因子受体β(platelet-derived growth factor receptor-β,PDGFR-β)在上丘神经元的作用。方法:采用免疫细胞化学法和图像分析技术观察正常成年小鼠和PDGFR-β基因敲除小鼠上丘内Otx2和小白蛋白(parvalbumin,PV)免疫反应阳性神经元的形态、数目、大小及分布。结果:PDGFR-β基因敲除小鼠上丘内Otx2和PV免疫反应阳性神经元的基本形态及分布特征与正常小鼠无明显差别,即Otx2免疫反应阳性神经元密集地分布于上丘的浅层,而PV免疫反应阳性神经元则分布于上丘的各层。但这两种神经元的数目在PDGFR-β基因敲除小鼠却明显减少,其平均直径也较正常小鼠者明显为小。结论:PDGFR-β可能通过Otx2和PV等神经化学物质,参与上丘的功能形成与发育。     

金黄地鼠上丘和外侧膝状体之间的联系

本实验采用了顺行和逆行追踪技术,对金黄地鼠上丘与丘脑视核团的纤维联系进行了实验观察。一、用尼氏和Loyez染色法,对4只正常金黄地鼠上丘和外侧膝状体背核和腹核的正常结构做了观察。二、3~H-亮氨酸和3~H-脯氨酸注入动物上丘不同部位(4只,存活期一天)后,可见神经末梢标记于同侧的外侧膝状体背核和腹核的外侧部位。若注射部位在上丘外侧,其投射部位在外侧膝状体背核和腹核的尾外侧;注射部位移向内侧,投射部位移向吻外侧。三、将HRP注入外侧膝状体背核(4只,存活期一天)或腹核(2只,存活期一天)或后外侧核(2只,存活期一天)后,在同侧上丘浅层见有标记神经元。在上丘深层则未见。本实验说明了上丘浅层的神经元对同侧的外侧膝状体背核和腹核有局部定位的投射,并按视野和视网膜将该投射作定位排列。     

Visually-induced NGFI-A protein expression in the calbindin-, parvalbumin- and nitric oxide synthase-neuronal populations of the rat superior colliculus

The expression of the immediate early gene NGFI-A in the nervous system is induced by sensory stimulation and seems to be related to long-term synaptic plasticity. We have used double-labeling immunohistochemistry to identify calbindin (CB)(+), parvalbumin (PV)(+) and neuronal nitric oxide synthase (nNOS)(+) neurons that also expressed the protein encoded by this immediate early gene after light-exposure on in the superficial layers of the rat superior colliculus (sSC). The majority of the NGFI-A(+) cells were not double-labeled for the tested markers. In the stratum zonale+stratum griseum superficiale (SZ/SGS), only 17.8%, 8.0% and 12.1% of NGFI-A(+) cells were also labeled for CB, PV or nNOS, respectively. In the stratum opticum (SO), only 10.5% of the NGFI-A(+) cells were also CB(+). Furthermore, only a small subset of each population expressed the NGFI-A protein after light-exposure. In the SZ/SGS, 35.7% of the CB(+), 32.1% of the PV(+) and 26.6% of the nNOS(+) neurons also expressed the NGFI-A. In the SO, 31.7% of the CB(+) neurons also expressed the NGFI-A. The proportional distribution of the nNOS(+)/NGFI-A(+) neurons throughout the SZ/SGS layers showed a slight but significant rostro-caudal gradient. No significant difference was observed for the other markers, indicating homogeneous activation of these populations throughout the retinotopic map. Our results suggest that the visually-driven NGFI-A expression is not restricted to a specific population of the sSC and that visual processing in this structure, as assessed by the expression of this candidate-plasticity protein, involves the activation of subsets of ascending and non-ascending projection neurons.     

28周人胎视皮质含钙结合蛋白神经元的区域分布

用免疫细胞化学方法研究了28周人胎树皮质17区和18区含CALBINDN(CB)及含PARVALBUMIN(PV)神经元的分布.结果发现,17区会CB及台PV神经元的数量均较18区者多得多,而且与18区比较,它们还可见于皮质较浅的层次,使 17/18区交界处明显可辨.结合我们对人类新皮质含CB及含PV神经元的发育研究结果,本实验结果提示,人类视皮质17区神经元的发育和成熟早于18区神经元.     

Immunocytochemical Localization of Calbindin D28K,Calretinin, and Parvalbumin in Bat Superior Colliculus

The purpose of this study was to investigate the localization of cells containing the calcium-binding proteins (CBPs) calbindin D28K (CB), calretinin (CR), and parvalbumin (PV) in the superior colliculus (SC) of the bat using immunocytochemistry. CB-immunoreactive (IR) cells formed a laminar tier within the upper superficial gray layer (SGL), while CR-IR cells were widely distributed within the optic layer (OL). Scattered CR-IR cells were also found within the intermediate gray, white, and deep gray layers. By contrast, PV-IR cells formed a laminar tier within the lower SGL and upper OL. Scattered PV-IR cells were also found throughout the intermediate layers, but without a specific laminar pattern. The CBP-IR cells varied in size and morphology: While most of the CB-IR cells in the superficial layers were small round or oval cells, most CR-IR cells in the intermediate and deep layers were large stellate cells. By contrast, PV-IR cells were small to large in size and included round or oval, stellate, vertical fusiform, and horizontal cells. The average diameters of the CB-, CR-, and PV-IR cells were 11.59, 17.17, and 12.60 μm, respectively. Double-immunofluorescence revealed that the percentage of co-localization with GABA-IR cells was 0.0, 0.0, and 10.27% of CB-, CR-, and PV-IR cells, respectively. These results indicate that CBP distribution patterns in the bat SC are unique compared with other mammalian SCs, which suggest functional diversity of these proteins in visually guided behaviors.     

Nitric oxide synthase immunoactivity and NADPH diaphorase enzyme activity in neurons of the gastrointestinal tract of the toad, Bufo marinus.

The presence of nitric oxide synthase (NOS) was demonstrated immunohistochemically, and NADPH diaphorase was demonstrated by enzyme histochemistry in neurons throughout the gastrointestinal tract of the anuran amphibian, Bufo marinus. Successive staining showed that NOS immunoreactivity and NADPH diaphorase activity occurred in precisely the same subgroup of enteric neurons. Subsequent detailed studies of the distribution of these neurons were made using NADPH diaphorase histochemistry. Numerous reactive nerve cell bodies and fibres were found in the myenteric plexus from the esophagus to the cloaca. A dense innervation of the longitudinal and circular muscle layers occurred throughout the gastrointestinal tract. The lamina muscularis mucosae was only prominent in the stomach, where it was sparsely innervated. Reactive nerve cell bodies were common in the submucosa of the large intestine, less common in the small intestine and extremely rare in the stomach and esophagus. Reactive fibres contributed to subepithelial plexuses in the esophagus, colon, rectum and cloaca. It is concluded that NOS/NADPH diaphorase is conserved amongst vertebrate classes and that NO is a likely neurotransmitter in the toad gastrointestinal tract.     

Distribution of choline acetyltransferase and NADPH diaphorase in the spinal cord of the pigeon

Acetylcholine is the neurotransmitter of somatic and autonomic motor systems of the spinal cord. However, there are also intrinsic cholinergic systems which have modulatory functions. Modulatory functions have also been assigned to nitric oxide (NO). Acetylcholine is synthesized by choline acetyltransferase and NO by nitric oxide synthase, which is a NADPH diaphorase. The distribution of both enzymes in the mammalian spinal cord is well known. However, there is a lack of comparative data in avian species. Therefore, the distribution of both enzymes in the spinal cord of the pigeon was studied using histochemical and immunohistochemical methods. Aside from somatic motor neurons and autonomic preganglionic neurons choline acetyltransferase-immunoreactivity was found throughout the spinal cord in lamina III of the superficial dorsal horn and near the central canal. The location of choline acetyltransferase-positive preganglionic neurons in the centrally located column of Terni and the lack of an intermediolateral column typical of the mammalian spinal cord can be confirmed. In lumbosacral segments the axons of centrally located cholinergic neurons crossed to the contralateral side to form a tract in the ventral funiculus, which then innervates the contralateral grey substance. A dense band of NADPH diaphorase staining was found in lamina II and in centrally located neurons of all segments. Part of the centrally located neurons double-labelled for choline acetyltransferase and NADPH diaphorase. In contrast to mammals, preganglionic neurons labelled only weakly for NADPH diaphorase. Altogether, despite the divergent evolution of both classes of vertebrate intrinsic modulatory choline acetyltransferase and NADPH diaphorase systems of birds seem to be largely similar to those of the mammalian spinal cord.     

Calretinin- and parvalbumin-immunoreactive neurons in the rat main olfactory bulb do not express NADPH-diaphorase activity

The presence of nitric oxide synthase (NOS) in neuronal elements expressing the calcium-binding proteins calretinin (CR) and parvalbumin (PV) was studied in the rat main olfactory bulb. CR and PV were detected by using immunocytochemistry and the nitric oxide (NO) -synthesizing cells were identified by means of the reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-diaphorase) direct histochemical method. The possible coexistence of NADPH-diaphorase and each calcium-binding protein marker was determined by sequential histochemical-immunohistochemical double-labeling of the same sections. Specific neuronal populations were positive for these three markers. A subpopulation of olfactory fibers and olfactory glomeruli were positive for either NADPH-diaphorase or CR. In the most superficial layers, groups of juxtaglomerular cells, superficial short-axon cells and Van Gehuchten cells demonstrated staining for all three markers. In the deep regions, abundant granule cells were NADPH-diaphorase- and CR-positive and a few were PV-immunoreactive. Scarce deep short-axon cells demonstrated either CR-, PV-, or NADPH-diaphorase staining. Among all these labeled elements, no neuron expressing CR or PV colocalized NADPH-diaphorase staining. The present data contribute to a more detailed classification of the chemically- and morphologically-defined neuronal types in the rodent olfactory bulb. The neurochemical differences support the existence of physiologically distinct groups within morphologically homogeneous populations. Each of these groups would be involved in different modulatory mechanisms of the olfactory information. In addition, the absence of CR and PV in neuronal groups displaying NADPH-diaphorase, which moreover are calmodulin-negative, indicate that the regulation of NOS activity in calmodulin-negative neurons of the rat olfactory bulb is not mediated by CR or PV.     

Relationship of neuronal vulnerability and calcium binding protein immunoreactivity in ischemia

Summary The relationship between neuronal calcium binding protein content (calbindin D_28K: CaBP and parvalbumin : PV) and vulnerability to ischemia was studied in different regions of the rat brain using the four vessel occlusion model of complete forebrain ischemia. The areas studied, i.e. the hippocampal formation, neocortex, neostriatum and reticular thalamic nucleus (RTN), show a characteristic pattern of CaBP and PV distribution, and are involved in ischemic damage to different degrees. In the hippocampal formation CaBP is present in dentate granule cells and in a subpopulation of the CA1 pyramidal cells, the latter being the most and the former the least vulnerable to ischemia. Non-pyramidal cells containing CaBP in these regions survive ischemia, whereas PV-containing non-pyramidal cells in the CA1 region are occasionally lost. Hilar somatostatin-containing cells and CA3 pyramidal cells contain neither PV nor CaBP. Nevertheless, the latter are resistant to ischemia and the former is the first population of cells that undergoes degeneration. Supragranular pyramidal neurons containing CaBP are the most vulnerable cell group in the sensory neocortex. In the RTN the degenerating neurons contain both PV and CaBP. In the neostriatum, ischemic damage involves both CaBP-positive and negative medium spiny neurons, although the degeneration always starts in the dorsolateral neostriatum containing relatively few CaBP-positive cells. The giant cholinergic interneurons of the striatum contain neither CaBP nor PV, and they are the most resistant cell type in this area. These examples suggest the lack of a consistent and systematic relationship between neuronal CaBP or PV content and ischemic vulnerability. It appears that some populations of cells containing CaBP or PV are more predisposed to ischemic cell death than neurons lacking these proteins. These neurons may express high levels of calcium binding proteins because their normal activity may involve a high rate of calcium uptake and/or intraneuronal release.     

大鼠下丘脑室旁核内一氧化氮合酶神经元的生后发育

应用 NADPH-黄递酶组织化学和一氧化氮合酶 (NOS)免疫组织化学方法以及计算机图像分析 ,观察 NOS神经元在大鼠下丘脑室旁核 (PVN)生后发育各阶段的形态及分布特征。结果显示 ,1d时 PVN内已有 NOS神经元。随着生长发育 ,PVN的面积逐渐变化 ,NOS神经元主要集中在 PVN的外侧大细胞部及腹侧部 ,细胞逐渐增多 ,胞体的平均截面积逐渐变大 ,平均灰度值逐渐降低。14d以后至成年鼠 (90 d)以上变化不明显。结果提示 ,PVN中 NOS神经元的生后发育和成熟主要在 14d前 ,尤以 7d至 14d为关键时期     

Localization of Nitric Oxide Synthase-containing Neurons in the Bat Visual Cortex and Co-localization with Calcium-binding Proteins

Microchiroptera (microbats) is a suborder of bats thought to have degenerated vision. However, many recent studies have shown that they have visual ability. In this study, we labeled neuronal nitric oxide synthase (nNOS)—the synthesizing enzyme of the gaseous non-synaptic neurotransmitter nitric oxide—and co-localized it with calbindin D28K (CB), calretinin (CR), and parvalbumin (PV) in the visual cortex of the greater horseshoe bat (Rhinolophus ferrumequinum, a species of microbats). nNOS-immunoreactive (IR) neurons were found in all layers of the visual cortex. Intensely labeled neurons were most common in layer IV, and weakly labeled neurons were most common in layer VI. Majority of the nNOS-IR neurons were round- or oval-type neurons; no pyramidal-type neurons were found. None of these neurons co-localized with CB, CR, or PV. However, the synthesis of nitric oxide in the bat visual cortex by nNOS does not depend on CB, CR, or PV.     

Restricted co‐localization of glutamate and dopamine in neurons of the adult sea lamprey brain

Co‐localization of dopamine with other classical neurotransmitters in the same neuron is a common phenomenon in the brain of vertebrates. In mammals, some dopaminergic neurons of the ventral tegmental area and the hypothalamus have a glutamatergic co‐phenotype. However, information on the presence of this type of dopaminergic neurons in other vertebrate groups is very scant. Here, we aimed to provide new insights on the evolution of this neuronal co‐phenotype by studying the presence of a dual dopaminergic/glutamatergic neuron phenotype in the central nervous system of lampreys. Double immunofluorescence experiments for dopamine and glutamate in adult sea lampreys revealed co‐localization of both neurotransmitters in some neurons of the preoptic nucleus, the nucleus of the postoptic commissure, the dorsal hypothalamus and in cerebrospinal fluid‐contacting cells of the caudal rhombencephalon and rostral spinal cord. Moreover, co‐localization of dopamine and glutamate was found in dopaminergic fibres in a few brain regions including the lateral pallium, striatum, and the preoptic and postoptic areas but not in the brainstem. Our results suggest that the presence of neurons with a dopaminergic/glutamatergic co‐phenotype is a primitive character shared by jawless and jawed vertebrates. However, important differences in the distribution of these neurons and fibres were noted among the few vertebrates investigated to date. This study offers an anatomical basis for further work on the role of glutamate in dopaminergic neurons.     

nNOS阳性神经元支配雄性大鼠球海绵体肌和坐骨海绵体肌

为了证实一氧化氮是否参与调节球海绵体肌和坐骨海绵体肌的功能 ,本研究用 CB-HRP逆行追踪结合 n NOS免疫细胞化学的技术 ,对支配雄性大鼠球海绵体肌和坐骨海绵体肌的神经元进行了研究 ,并结合 NADPH-d组化技术对雄性大鼠腰、骶髓的 NADPH-d阳性细胞和突起的分布进行了观察。结果发现 :( 1)支配球海绵体肌和坐骨海绵体肌的 Onuf核内存在着 CB-HRP与 n NOS双重反应细胞、CB-HRP阳性细胞、n NOS阳性细胞 ;n NOS阳性细胞还可见于后连合核、骶副交感核、背角等部位。( 2 ) NADPH-d阳性神经元在腰、骶髓主要位于中央管周围、后连合核、骶副交感核、背角等部位。本研究为 NO作为神经活性物质参与球海绵体肌和坐骨海绵体肌功能的调节提供了形态学证据     

Parvalbumin and calbindin D-28K immunoreactive neurons in area MT of rhesus monkey

The chemical characteristics of the neurons of the motion sensitive visual area, area MT, remain to be established. We studied the distribution pattern of two calcium binding proteins, parvalbumin (PV) and calbindin D28K (CB) in this area, using specific monoclonal antibodies and the peroxidase-antiperoxidase (PAP) immunohistochemical technique. Aldehyde fixed 30-micron-thick cryostat sections from area MT of five animals were processed free floating for immunohistochemical staining. Besides studying the morphological characteristics of PV and CB positive neurons, quantitative analysis was carried out to determine their (1) perikaryal area (Pa) and diameter, (2) numerical densities (NV)/mm3 cortical tissue, (3) absolute number (NC) in a column of cortex under 1 mm2 cortical surface along with (4) layerwise absolute number (NL) under 1 mm2 cortical surface and (5) laminar percentage distribution of immunoreactive (IR) neurons. Quantitative analysis was carried out using a Leica QMC 500 image analysis system connected to a DMRE microscope. The results showed that both types of IR neurons were localized to all cortical layers except layer I. The PV +ve neurons were equidistributed between the supra- and infragranular layers, with the highest percentage being present in layer III (45%) followed by layer V (21%). The CB +ve neurons, on the other hand, were predominantly localized in supragranular layers, with the highest percentage being in layer III (54%) and the next highest percentage in layer II (18%). The average Pa and diameter of PV +ve neurons were found to be 96.90 +/- 28.43 micron 2 and 11.01 +/- 1.61 microns respectively. The CB +ve neurons were significantly smaller in size than the PV +ve neurons, with average Pa and diameter of the former being 92.23 +/- 26.18 micron 2 and 10.39 +/- 1.23 microns respectively. The NV for PV and CB +ve neurons showed ranges of 3157-3894 and 2303-2585, with means of 3347 +/- 285 (+/- SD) and 3436 +/- 100 respectively. The values for NC showed ranges of 5230-5444 and 4020-4268 with means of 5378 +/- 85 and 4167 +/- 95 for PV and CB neurons respectively. Variations in size together with the differential distribution of these neurons in the cortical layers may indicate their involvement in different functional circuitaries.