Metagenomic sequencing revealed the regulative effect of Danshen and Honghua herb pair on the gut microbiota in rats with myocardial ischemia injury.

In recent years, more and more evidence has shown that the disorder of gut microbiota (GM) is closely correlated with myocardial ischemia (MI). Even though the Danshen and Honghua herb pair (DHHP) is widely used in treating cardiovascular disease in China and exhibits obvious clinical efficacy on MI, the anti-MI mechanism of DHHP remains and needs to be explored in depth. Thus, in this study, we investigated whether the amelioration effect and molecular mechanism of DHHP on MI were related to regulating GM through pharmacodynamics evaluation and metagenomic sequencing. Histopathological testing results showed that DHHP treatment could alleviate the pathological changes of myocardial tissue in the acute MI (AMI) rats induced by isoproterenol (ISO), especially structural disorder, irregular distribution, and enlargement of the myocardial space. These pathological changes were all alleviated to some extent by DHHP treatment. Biochemical analysis results suggested that compared with the control group, the serum levels of AST, CTn-I, CK-MB, and TNF-α in model group rats were notably decreased, and the CAT and SOD levels in serum were markedly increased. These abnormal trends were significantly reversed by DHHP treatment. Furthermore, metagenomic sequencing analysis results indicated that DHHP could improve disorders in the composition and function of GM in AMI rats, mainly reflected in increasing diversity and richness, and obviously enhancing the abundance of Bacteroides fluxus, B. uniformis, B. stercoris, Roseburia hominis, Schaedlerella arabinosiphila, and R. intestinalis, and reducing the abundance of Enterococcus avium and E. canintestini, which were associated with purine metabolism, tyrosine metabolism, cyanoamino acid metabolism, and glutathione metabolism. In conclusion, DHHP may attenuate ISO-induced MI by regulating the structure, composition, and function of GM, thus contributing to further our understanding of the anti-MI mechanisms of DHHP and providing new therapeutic ideas and diagnostic targets for the clinical studies of MI.

Paeoniflorin Ameliorates Colonic Fibrosis in Rats with Postinfectious Irritable Bowel Syndrome by Inhibiting the Leptin/LepRb Pathway.

Postinfectious irritable bowel syndrome (PI-IBS) is a highly prevalent gastrointestinal disorder associated with immune dysregulation and depression- and anxiety-like behaviors. Through traditional medicine, the active ingredient of Paeoniae Radix called paeoniflorin (PF) was previously found to prevent the symptoms of PI-IBS. However, there is limited information on the effects of PF on intestinal function and depression- and anxiety-like symptoms in PI-IBS animal models. Here, we aimed to determine the effects of PF treatment on the symptoms of PI-IBS in a rat model. The PI-IBS rat model was established via early postnatal sibling deprivation (EPSD), trinitrobenzenesulfonic acid (TNBS), and chronic unpredictable mild stress (CUMS) stimulation and then treated with different dosages of PF (10, 20, and 40 mg/kg) and leptin (1 and 10 mg/kg). The fecal water content and body weight were measured to evaluate the intestinal function, while the two-bottle test for sucrose intake, open field test (OFT), and elevated plus maze test (EMT) were performed to assess behavioral changes. The serum leptin levels were also measured using an enzyme-linked immunosorbent assay. Furthermore, the expressions of leptin and its receptor, LepRb, were detected in colonic mucosal tissues through an immunohistochemical assay. The activation of the PI3K/AKT signaling pathway and the expression of brain-derived neurotrophic factor (BDNF) were also detected via western blotting. After the experimental period, the PI-IBS rats presented decreased body weight and increased fecal water content, which coincided with elevated leptin levels and heightened depression- and anxiety-like behaviors (e.g., low sucrose intake, less frequency in the center areas during OFT, and fewer activities in the open arms during EMT). However, the PF treatment ameliorated these observed symptoms. Furthermore, PF not only inhibited leptin/LepRb expression but also reduced the PI3K/AKT phosphorylation and BDNF expression in PI-IBS rats. Notably, cotreatment with leptin (10 mg/kg) reduced the effects of PF (20 mg/kg) on colonic fibrosis, leptin/LepRb expression, and PI3K/AKT activation. Therefore, our findings suggest that leptin is targeted by PF via the leptin/LepRb pathway, consequently ameliorating the symptoms of PI-IBS. Our study also contributes novel insights for elucidating the pharmacological action of PF on gastrointestinal disorders and may be used for the clinical treatment of PI-IBS in the future.

Modulation effects of danshen-honghua herb pair on gut microbiota of acute myocardial ischemia model rat.

In the recent years, a growing number of studies have shown that the occurrence of myocardial ischemia (MI) is closely related to the gut microbiota (GM). The Danshen-Honghua herb pair (DHHP), a classic combination in traditional Chinese herbal formulas, has been widely applied throughout history to cure cardiovascular disease, exhibiting remarkable clinical efficacy to treat ischemic heart disease (IHD). However, the intrinsic regulation mechanism of DHHP in treating MI remains unclear. This study aims to investigate the possible protective mechanism of DHHP in rats with acute myocardial ischemia (AMI) induced by isoproterenol (ISO) through 16S rRNA gene sequencing technique. Pharmacodynamic results showed that DHHP significantly ameliorated the pathological changes and improved the abnormal cardiac enzymes levels in the AMI rats. In addition, GM analysis demonstrated that DHHP effectively ameliorated the ISO-induced dysbiosis of the GM community, mainly by enhancing the GM diversity and increasing the relative abundance of Bacteroides, Roseburia, unclassified_f__Lachnospiraceae, and Lachnospiraceae_NK4A136_group, the abundance ratio of Bacteroidetes to Firmicutes, and decreasing the relative abundance of Escherichia-Shigella and Enterococcus. In summary, this study revealed that DHHP could improve ischemic myocardial injury in rats, and that its regulation mechanism is associated with significantly ameliorating the composition of GM, thus contributing to further our understanding of the anti-MI mechanisms of DHHP.

Suppression of PTRF Alleviates Post-Infectious Irritable Bowel Syndrome via Downregulation of the TLR4 Pathway in Rats.

Background: Accumulating evidence suggests that the polymerase I and transcript release factor (PTRF), a key component of the caveolae structure on the plasma membrane, plays a pivotal role in suppressing the progression of colorectal cancers. However, the role of PTRF in the development of functional gastrointestinal (GI) disorders remains unclear. Post-infectious irritable bowel syndrome (PI-IBS) is a common functional GI disorder that occurs after an acute GI infection. Here, we focused on the role of PTRF in the occurrence of PI-IBS and investigated the underlying mechanisms. Methods: Lipopolysaccharide (LPS) (5 µg/ml) was used to induce inflammatory injury in human primary colonic epithelial cells (HCoEpiCs). Furthermore, a rat model of PI-IBS was used to study the role of PTRF. Intestinal sensitivity was assessed based on the fecal water content. A two-bottle sucrose intake test was used to evaluate behavioral changes. Furthermore, shRNA-mediated knockdown of PTRF was performed both in vitro and in vivo. We detected the expression of PTRF in colonic mucosal tissues through immunohistochemistry (IHC), western blotting (WB), and immunofluorescence (IF) analysis. Luciferase activity was quantified using a luciferase assay. Co-localization of PTRF and Toll-like receptor 4 (TLR4) was detected using IF analysis. The activation of the signaling pathways downstream of TLR4, including the iNOs, p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) pathways, was detected via WB. The levels of NO, IL-1ß, IL-6, and TNF-α were measured using enzyme-linked immunosorbent assays. Results: LPS significantly induced PTRF expression and signaling downstream of TLR4, including p38, ERK, and JNK pathways, in HCoEpiCs. Moreover, shRNA-mediated knockdown of PTRF in HCoEpiCs significantly decreased the phosphorylation of JNK, ERK, and p38 and iNOS expression. In PI-IBS rats, the lack of PTRF not only reduced fecal water content and suppressed depressive behavior but also increased the body weight. Furthermore, we found a strong co-localization pattern for PTRF and TLR4. Consistently, the lack of PTRF impaired TLR4 signaling, as shown by the decreased levels of p-JNK, p-ERK, and p-p38, which are upstream factors involved in iNOS expression. Conclusion: PTRF promoted PI-IBS and stimulated TLR4 signaling both in vitro and in vivo. The results of this study not only enlighten the pathogenesis of PI-IBS but also help us understand the biological activity of PTRF and provide an important basis for the clinical treatment of PI-IBS by targeting PTRF.

Synchronization between frontal eye field and area V4 during free-gaze visual search.

Information flow between the prefrontal and visual cortices is critical for visual behaviors such as visual search. To investigate its mechanisms, we simultaneously recorded spike and local field potential (LFP) signals in the frontal eye field (FEF) and area V4 while monkeys performed a free-gaze visual search task. During free-gaze search, spike-LFP coherence between FEF and V4 was enhanced in the theta rhythm (4-8 Hz) but suppressed in the alpha rhythm (8-13 Hz). Cross-frequency couplings during the Cue period before the search phase were related to monkey performance, with higher FEF theta-V4 gamma coupling and lower FEF alpha-V4 gamma coupling associated with faster search. Finally, feature-based attention during search enhanced spike-LFP coherence between FEF and V4 in the gamma and beta rhythms, whereas overt spatial attention reduced coherence at frequencies up to 30 Hz. These results suggest that oscillatory coupling may play an important role in mediating interactions between the prefrontal and visual cortices during visual search.

Effect of NMDA on proliferation and apoptosis in hippocampal neural stem cells treated with MK-801.

The purpose of the present study was to investigate effects of N-methyl-D-aspartate (NMDA) on proliferation and apoptosis of hippocampal neural stem cells (NSCs) treated with dizocilpine (MK-801). Cultures of hippocampal NSCs were randomly divided into four groups consisting of an untreated control, cells treated with MK-801, NMDA and a combination of MK801 and NMDA (M+N). Proliferative and apoptotic responses for each of the experimental groups were determined by MTS and flow cytometry. The results revealed that MK-801 and NMDA exerted significant effects on hippocampal NSCs proliferation. Cell survival rates decreased in MK-801, NMDA and M+N treated groups compared with the control group. Cells survival rates in NMDA and M+N treated groups increased compared with the MK-801 treated group. MK-801 and NMDA were demonstrated to significantly affect apoptosis in hippocampal NSCs. Total and early stages of apoptosis in MK-801 and NMDA groups significantly increased compared with the control group. Total and early apoptosis of NSCs in the M+N group significantly decreased compared with MK-801 and NMDA groups. Late apoptosis of NSCs in MK-801 and NMDA groups significantly decreased compared with the control group. Late apoptosis of NSCs in the M+N group significantly increased compared with MK-801 and NMDA groups. The present study revealed that MK-801 inhibited proliferation and increased apoptosis in hippocampal NSCs. NMDA may reduce the neurotoxicity induced by MK-801, which may be associated with its activity towards NMDA receptors and may describe a novel therapeutic target for the treatment of schizophrenia.

Dihydroartemisinin alleviates oxidative stress in bleomycin-induced pulmonary fibrosis.

AIMS: Dihydroartemisinin has been shown to inhibit the development of pulmonary fibrosis in rats, but its mechanism has yet to be elucidated. This study aimed to determine the mechanisms of dihydroartemisinin in bleomycin-induced pulmonary fibrosis in a rat model. MAIN METHODS: Morphological changes and collagen deposition were analyzed via hematoxylin-eosin staining and Masson staining and the expression of biotic-factor-related oxidative stress in lung tissues was assayed with standard assay kits. The expressions of α-SMA, E-cadherin, and Nrf2/HO-1 were detected by Western blot and RT-PCR, and the cell morphology and proliferation of cultured type II alveolar epithelial cells (AECs) were assessed via microscopy and immunocytochemical assay. KEY FINDINGS: Dihydroartemisinin treatment significantly decreased the level of oxidative stress and collagen synthesis and inhibited AECs differentiation in bleomycin-induced pulmonary fibrosis compared to the control group (P < 0.001). SIGNIFICANCE: Our results indicated that dihydroartemisinin might decrease oxidative damage to attenuate lung injury and fibrosis.

Expression of NR1 and apoptosis levels in the hippocampal cells of mice treated with MK­801.

The aim of the present study was to investigate the characteristics of N­methyl­D­aspartate receptor R1 (NR1) expression and apoptosis in the nerve cells of the hippocampus in schizophrenia­like mice. C57BL/6 mice were randomly allocated to the following groups: i) Blank group; ii) MK­801 group; iii) MK­801+NMDA group, according to body weight. The NMDAR antagonist, MK­801 (0.6 mg/kg/d) was intraperitoneally injected daily for 14 days to induce a schizophrenia­like phenotype mouse model, and the effect of the NMDA injection via the lateral ventricle was observed. The results demonstrated that the number of NR1 positive cells in the MK­801 group increased in the CA1 and DG regions, indicating that NMDA may reverse this change. The level of damage decreased in the MK­801 treated group when compared with the blank group in the CA3 region. The protein expression of NR1 increased however, at the mRNA expression level, NR1 was lower in the MK­801 treated group when compared to the blank group; NMDA also reversed this change. In addition, early and total apoptosis detected in the hippocampal nerve cells was significantly increased in the MK­801 group when compared with the blank group, which was reversible following treatment with NMDA. These results indicated that NMDA may regulate the expression of NR1 and suppress apoptosis in hippocampal nerve cells in schizophrenia­like mice. Thus, NR1 may be a promising therapeutic target for the treatment of schizophrenia.

Analysis of Clinicopathological Features and Prognostic Factors in 39 Cases of Bladder Neuroendocrine Carcinoma.

AIM: Through analysis and summarization of clinicopathological features, immunohistochemical expression, pathological diagnostic criteria, prognostic and other factors in patients suffering from bladder neuroendocrine carcinoma (BNEC), a better understanding of BNEC could be achieved to provide solid evidence for clinicopathology and prognosis. MATERIALS AND METHODS: The clinicopathological data of 39 cases of BNEC with up to 5-year follow-up data (median follow-up=650 days) were analyzed retrospectively based on immunohistochemical staining. Survival analyses were carried out using the Kaplan-Meier method and tested with the log-rank method. Multivariate Cox regression analysis was adopted to screen independent risk factors affecting patients' survival. In these 39 cases of BNEC, there were 26 cases of male patients, 13 female, with the proportion of male to female being 2:1. The ages of onset ranged from 44 to 86, with the median age being 62 and the average age 61.97 years, respectively. Histologically, referring to the WHO standard of neuroendocrine lung tumor classification, there were 7 cases of typical carcinoid tumors, 8 atypical carcinoid, 12 small-cell carcinomas and 12 large-cell carcinomas. In these cases there were 11 cases of featured urothelium carcinomas and 9 cases of adenocarcinomas. RESULTS: Immunohistochemical staining showed that, in these 39 cases of BNEC, the positive expression for the neuroendocrinic markers, including neural cell adhesion molecule 56 (CD56), synaptophysin (Syn), chromogranin A (CgA), neuron-specific enolase (NSE), thyroid transcription factor-1 (TTF-1), cytokeratin (CK) and cytokeratin 7 (CK7), accounted for 39/39, 27/39, 18/39, 39/39, 19/39, 10/39 and 8/39, respectively. In contrast, cytokeratin 20 (CK20), protein 63 (P63), human melanoma black 45 (HMB45), S-lfln protein 100 (S-100) and leukocyte common antigen (LCA) were all negatively expressed. During the follow-up period, 12 patients died. The 1-, 3- and 5-year overall survival (OS) rates were 76.92%, 74.36% and 69.23%. CONCLUSION: BNEC is one of the most malignant tumors with severe invasiveness and poor prognosis. Immunohistochemistry revealed that CD56, Syn, CgA, NSE, TTF-1, CK, CK7, CK20, P63, HMB45, S-100 protein and LCA immune markers play important roles in diagnosis and differentiation. Many factors, including the patient's age, size and shape of the tumor, operative method, perineuronal invasion, vascular invasion, distant organ metastasis and pathological type, show great difference in influencing OS time of patients, among which the size of the tumor, no invasion, vascular invasion and distant organ metastasis are independent risk factors affecting prognosis (survival time). Radical cystectomy is the prior alternative to treat this tumor.

Reduced expression levels of let-7c in human breast cancer patients.

Circulating microRNAs (miRNAs) are important in the diagnosis of a number of diseases, since serum or plasma miRNAs are more stable compared with miRNA isolated from blood samples. The aim of the present study was to investigate the association between the expression levels of serum let-7c miRNA and the clinical diagnosis of breast cancer (BC). The circulating let-7c levels of 90 BC patients and 64 healthy controls were determined by performing a reverse transcription-quantitative polymerase chain reaction assay. The results demonstrated that let-7c expression was downregulated in the BC tissues compared with the paracarcinoma control tissues. In addition, the let-7c expression in the serum of BC patients was significantly lower compared with the healthy controls (P<0.01). Using a cutoff value of 0.374×103 copies/ml, the serum expression levels of let-7c exhibited 87.5% sensitivity and 78.9% specificity for distinguishing BC patients from healthy controls (area under the receiver operating characteristic curve, 0.848; 95% confidence interval, 0.785-0.911). Furthermore, the results demonstrated that the serum expression levels of let-7c were significantly higher in premenopausal compared with postmenopausal patients (P<0.05), supporting the hypothesis that postmenopausal status may affect the serum expression levels of let-7c. However, no statistically significant differences were detected in the serum levels of let-7c between ER (or PR)-positive and -negative patients. Therefore, the current study hypothesized that serum let-7c may be used as a novel and valuable biomarker for the diagnosis of BC.

Higher expression of circulating miR-182 as a novel biomarker for breast cancer.

MicroRNAs (miRNAs), present in the serum in a stable and reproducible manner, may be used as biomarkers for various diseases. Few studies have previously investigated circulating miRNAs in the peripheral blood of breast cancer (BC) patients. To identify the role of serum miR-182 levels in BC, the present study detected miR-182 levels in the serum of 46 BC patients and 58 controls, by quantitative PCR. The results showed that the serum miR-182 levels in BC patients were significantly higher compared with the serum of healthy controls (P<0.01). The miR-182 was also overexpressed in the BC tissues compared with the para-carcinoma tissues. Furthermore, the serum levels of miR-182 in the estrogen receptor (ER)-positive patients were considerably lower compared with those in the ER-negative patients. The serum levels of miR-182 in the progesterone receptor (PR)-positive patients were also found to be lower compared with those in the PR-negative patients. The current study highlights results consistent with miR-182 as a novel and valuable biomarker for the diagnosis of BC.

[The analysis of Leber's hereditary optic neuropathy associated with mitochondrial tRNAAla C5601T mutation in seven Han Chinese families].

We reported here the clinical, genetic, and molecular characterization of Leber's hereditary optic neuropathy (LHON) with C5601T mutation in seven Chinese families. The ophthalmologic examinations of seven Chinese families who were clinically diagnosed LHON were conducted. Strikingly, these families exhibited very low penetrance of visual impairment, and the penetrance was 9.5%, 14.3%, 4.5%, 8.3%, 10.0%, 22.2% and 25.0%. Meanwhile, entire mitochondrial genome of seven probands was amplified by PCR using 24 pairs of oligonucleotide primers with overlapping fragments. Molecular analysis of mitochondrial DNA (mtDNA) in these pedigrees revealed the absence of three common LHON associated G11778A, G3460A and T14484C mutations but the presence of homoplastic LHON associated tRNAAla C5601T mutation in probands and other matrilineal relatives. These mtDNA polymorphism sites belongs to the Asian haplogroups G2, G2a1, G2a1, G2, G2b, G2a1 and G2. By analyzing mitochondrial genome, seven LHON families all carry the C5601T mutation. The C5601T mutation occurs at the highly conserved nucleotide (conventional position 59) of tRNAAla, thereby contributing to the structural formation and stabilization of functional tRNAs and leading to mitochondrial dysfunction involved in visual impairment. The incomplete penetrance of visual loss in these seven Chinese pedigrees strongly indicates that the tRNAAla C5601T mutation was itself insufficient to produce a clinical phenotype. The lack of functional mtDNA variants in these pedigrees ruled out the role of mitochondrial background in the phenotypic expression of visual loss. Therefore, nuclear backgrounds and environmental factors seem to be modifying factors for the phenotypic manifestation of the tRNAAla C5601T mutation in the seven Chinese families.

Millisecond-timescale optical control of neural dynamics in the nonhuman primate brain.

To understand how brain states and behaviors are generated by neural circuits, it would be useful to be able to perturb precisely the activity of specific cell types and pathways in the nonhuman primate nervous system. We used lentivirus to target the light-activated cation channel channelrhodopsin-2 (ChR2) specifically to excitatory neurons of the macaque frontal cortex. Using a laser-coupled optical fiber in conjunction with a recording microelectrode, we showed that activation of excitatory neurons resulted in well-timed excitatory and suppressive influences on neocortical neural networks. ChR2 was safely expressed, and could mediate optical neuromodulation, in primate neocortex over many months. These findings highlight a methodology for investigating the causal role of specific cell types in nonhuman primate neural computation, cognition, and behavior, and open up the possibility of a new generation of ultraprecise neurological and psychiatric therapeutics via cell-type-specific optical neural control prosthetics.

Cognitively directed spatial selection in the frontal eye field in anticipation of visual stimuli to be discriminated.

Single neuron activity was recorded in the frontal eye field (FEF) of monkeys trained to perform a difficult luminance discrimination task. The appearance of a cue stimulus informed the monkeys of the locations of two gray luminance stimuli that would appear within 500-1500ms. The monkeys were rewarded for making a saccade to the brighter of the two luminance stimuli, or if they were the same luminance, for making a saccade to the cue stimulus. Sixty percent (51/85) of FEF neurons exhibited elevated activity when the cue informed the monkeys that one of the luminance stimuli would appear in their response field (RF). This spatially selective anticipatory activity occurred without any visual stimulus appearing in their RF and was not related to saccade choice or latency. The responses of 27 of the anticipatory neurons (32% of the total sample) were also incompatible with the hypothesis that the activity represents saccade probability because they did not exhibit elevated activity for the cue stimulus which was the most probable saccade target. Behaviorally, monkeys exhibited improved perception at locations informed by cue than at unpredictable locations. These results provide physiological evidence that FEF serves an important role in endogenous spatial attention in addition to its well-known role in saccade production.

[Inherited mutations of MUTYH and colorectal cancer].

MUTYH, one of base-excision repair enzymes, is associated with human genetic disorders. Inherited biallelic mutations in the human MUTYH gene are responsible for an autosomal recessive syndrome-adenomatous colorectal polyposis (MUTYH associated polyposis, MAP), which significantly increases the risk of colorectal cancer (CRC). In this article we review the relationship between BER and the oxidative damage to DNA, the functional overlap of BER with other repair proteins, the molecular mechanism of tumourigenesis in MAP, and delineate the MUTYH polyposis phenotype and its prevention.

Foveal versus full-field visual stabilization strategies for translational and rotational head movements.

Because we view the world from a constantly shifting platform when our head and body move in space, vestibular and visuomotor reflexes are critical to maintain visual acuity. In contrast to the phylogenetically old rotational vestibulo-ocular reflex (RVOR), it has been proposed that the translational vestibulo-ocular reflex (TVOR) represents a newly developed vestibular-driven mechanism that is important for foveal vision and stereopsis. To investigate the hypothesis that the function of the TVOR is indeed related to foveal (as opposed to full-field) image stabilization, we compared the three-dimensional ocular kinematics during lateral translation and rotational movements with those during pursuit of a small moving target in four rhesus monkeys. Specifically, we tested whether TVOR rotation axes tilt with eye position as in visually driven systems such as pursuit, or whether they stay relatively fixed in the head as in the RVOR. We found a significant dependence of three-dimensional eye velocity on eye position that was independent of viewing distance and viewing conditions (full-field, single target, or complete darkness). The slopes for this eye-position dependence averaged 0.7 +/- 0.07 for the TVOR, compared with 0.6 +/- 0.07 for visually guided pursuit eye movements and 0.18 +/- 0.09 for the RVOR. Because the torsional tilt versus vertical gaze slopes during translation were slightly higher than those during pursuit, three-dimensional eye movements during translation could partly reflect a compromise between the two different solutions for foveal gaze control, that of Listing's law and minimum velocity strategies. These results with respect to three-dimensional kinematics provide additional support for a functional difference in the two vestibular-driven mechanisms for visual stability during rotations and translations and establish clearly the functional goal of the TVOR as that for foveal visual acuity.

Motor scaling by viewing distance of early visual motion signals during smooth pursuit.

The geometry of gaze stabilization during head translation requires eye movements to scale proportionally to the inverse of target distance. Such a scaling has indeed been demonstrated to exist for the translational vestibuloocular reflex (TVOR), as well as optic flow-selective translational visuomotor reflexes (e.g., ocular following, OFR). The similarities in this scaling by a neural estimate of target distance for both the TVOR and the OFR have been interpreted to suggest that the two reflexes share common premotor processing. Because the neural substrates of OFR are partly shared by those for the generation of pursuit eye movements, we wanted to know if the site of gain modulation for TVOR and OFR is also part of a major pathway for pursuit. Thus, in the present studies, we investigated in rhesus monkeys whether initial eye velocity and acceleration during the open-loop portion of step ramp pursuit scales with target distance. Specifically, with visual motion identical on the retina during tracking at different distances (12, 24, and 60 cm), we compared the first 80 ms of horizontal pursuit. We report that initial eye velocity and acceleration exhibits either no or a very small dependence on vergence angle that is at least an order of magnitude less than the corresponding dependence of the TVOR and OFR. The results suggest that the neural substrates for motor scaling by target distance remain largely distinct from the main pathway for pursuit.