Region-specific distribution of catecholamine afferents in primate cerebral cortex: A fluorescence histochemical analysis

The density, laminar distribution, spatial orientation, and intrahemispheric pathways of norepinephrine (NE)- and dopamine (DA)- containing axons were analyzed in a wide range of cytoarchitectonically distinct areas of cerebral cortex in the adult rhesus monkey by fluorescence histochemistry. Although the boundaries between most areas were rarely sharp, there were marked regional differences in density and distribution of monoamine afferents in different cortical regions. Fibers exhibiting typical DA-like morphology were found only in the temporal and frontal lobes including motor and premotor areas as well as anterior cingulate and prefrontal cortices. In contrast, NE-containing axons were present in all cerebral lobes, with notably high density in the somatosensory area and low numbers in primary visual cortex. Intracerebral distribution was characterized by a network of large preterminal axons coursing both anteroposteriorly and mediolaterally in layer VI and in the subjacent white matter. In most cytoarchitectonic regions examined, catecholamine (CA)-containing axons exhibited a bilaminar distribution into one superficial and one deep fiber band. The location and width of the two dense bands, as well as the orientation and relative density of fibers within them, was region specific. Although fluorescent axons were found at all cortical depths, layers I, and IV usually contained relatively few fluorescent axons while layers II–III and IV–V were often densely innervated. An observation that may reflect a specialization in gyrencephalic brains is the particularly dense CA innervation around sulcal invaginations in all cerebral lobes. The present results confirm previous biochemical evidence of regional heterogeneity in the concentration of DA and NE in the primate neocortex (Brown and Goldman, '77; Brain Res. 124:576–550) and provide the first anatomical demonstration of corresponding differences in the pattern and density of CA innervation in diverse cytoarchitectonic areas in rhesus monkey. These findings raise the possibility of seletive targets and functions for CA fibers in different layers and regions of the primate cortex.     

Take of rhesus-human reassortant tetravalent rotavirus vaccine in breast-fed infants

Rhesus-human reassortant tetravalent rotavirus vaccine at a titer of 4 x 10⁴ plaque forming units was evaluated for immmunogenicity in 194 6–8-week-old breast-fed Turkish infants. The vaccine was administered orally as a single dose following either a meal of breast milk or 30 ml of sodium bicarbonate-buffered soy milk formula. Four-fold or greater responses in rotavirus IgA ELISA antibody were detected in 62% and 65'% of the infants in the two groups, respectively ( p = 0.62). In a smaller comparison group of non-breast-fed infants, an IgA response was detected in 7 of 11 (64%) cases. In all vaccinees, a serological response was detected in 72% of the initially seronegative and 47% of the initially seropositive infants ( p = 0.001). We conclude that the take of rhesus-human reassortant tetravalent rotavirus vaccine in breast-fed infants is not compromised by breast feeding before vaccination. However, a higher titered preparation of the same vaccine may be required to improve overall immunogenicity in young infants, particularly in those with pre-vaccination rotavirus antibody.     

Co-administration of Flt-3 ligand counteracts the actions of thrombopoietin in myelosuppressed rhesus monkeys

This placebo-controlled study evaluated the efficacy of Flt-3 ligand (FL) combined with TPO in myelosuppressed rhesus monkeys. The monkeys were subjected to 5 Gy total body irradiation (TBI), resulting in 3 weeks of profound pancytopenia, and received either 5 microg/kg of rhesus TPO i.v. on d 1 (n = 4) and 100 microg/kg/d s.c. human FL (n = 4) or FL alone (n = 4) for 14 consecutive days and were compared with results from a concomitant study involving the administration of TPO alone (n = 4) or placebo (carrier; n = 4). The TPO/FL combination was considerably less effective than TPO alone, with a more profound nadir and a slower recovery to thrombocyte counts > 100 x 109/l, approaching recovery patterns of placebo controls. Leucocyte regeneration was similar in all animals. Monkeys treated with FL alone displayed a regeneration of reticulocytes and thrombocytes in the lower range of those of the placebo controls. Recovery of bone marrow (BM) cellularity was slightly accelerated in the TPO/FL-treated monkeys, but was not reflected by an increase in progenitor cells, in contrast to TPO alone. Monkeys treated with FL alone showed a BM reconstitution similar to placebo-treated controls. FL by itself was not effective as a therapeutic agent in this model for myelosuppression. As FL also suppressed BM CD34+ cell reconstitution, we concluded that FL competed with TPO at the level of immature cell differentiation.     

Effects of the mixed-action kappa/mu opioid agonist 8-carboxamidocyclazocine on cocaine- and food-maintained responding in rhesus monkeys

The present study evaluated the effects of 8-carboxamidocyclazocine (8-CAC), a novel mixed-action kappa/mu agonist with a long duration of action, on food- and cocaine-maintained responding in rhesus monkeys to assess the potential utility of 8-CAC as a medication for the treatment of cocaine dependence. The effects of acute and chronic (10 days) 8-CAC were examined in rhesus monkeys responding under a multiple schedule for both cocaine and food reinforcement. Acute 8-CAC (0.032-0.56 mg/kg, i.m.) dose-dependently eliminated cocaine-maintained responding in all three monkeys. However, doses of 8-CAC that decreased cocaine self-administration typically also decreased food-maintained responding, and 8-CAC-induced decreases in cocaine self-administration diminished during chronic 8-CAC treatment. These results confirm that 8-CAC acutely decreases cocaine self-administration. However, non-selective effects of 8-CAC on food-maintained responding and tolerance to 8-CAC effects on cocaine self-administration may limit its potential for the treatment of cocaine dependence.     

B-virus and free-ranging macaques, Puerto Rico

In Puerto Rico, risk for transmission of B-virus from free-ranging rhesus monkeys to humans has become a serious challenge. An incident with an injured rhesus monkey, seropositive for B-virus, resulted in inappropriate administration of antiviral postexposure prophylaxis. This incident underscores the importance of education about risks associated with interactions between humans and nonhuman primates.     

Neuronal activity in primate dorsolateral and orbital prefrontal cortex during performance of a reward preference task

An important function of the prefrontal cortex (PFC) is the control of goal-directed behaviour. This requires information as to whether actions were successful in obtaining desired outcomes such as rewards. While lesion studies implicate a particular PFC region, the orbitofrontal cortex (OFC), in reward processing, neurons encoding reward have been reported in both the OFC and the dorsolateral prefrontal cortex (DLPFC). To compare and contrast their roles, we recorded simultaneously from both areas while two rhesus monkeys (Macaca mulatta) performed a reward preference task. The monkeys had to choose between pictures associated with different amounts of a juice reward. Neuronal activity in both areas reflected the reward amount. However, neurons in the DLPFC encoded both the reward amount and the monkeys' forthcoming response, while neurons in the OFC more often encoded the reward amount alone. Further, reward selectivity arose more rapidly in the OFC than the DLPFC. These results are consistent with reward information entering the PFC via the OFC, where it is passed to the DLPFC and used to control behaviour.     

Synchrony dynamics in monkey V1 predict success in visual detection

Behavioral measures such as expectancy and attention have been associated with the strength of synchronous neural activity. On this basis, it is hypothesized that synchronous activity affects our ability to detect and recognize visual objects. To investigate the role of synchronous activity in visual perception, we studied the magnitude and precision of correlated activity, before and after stimulus presentation within the visual cortex (V1), in relation to a monkey's performance in a figure-ground discrimination task. We show that during the period of stimulus presentation a transition in synchronized activity occurs that is characterized by a reduction of the correlation peak height and width. Before stimulus onset, broad peak correlations are observed that change towards thin peak correlations after stimulus onset, due to a specific decrease of low-frequency components. The magnitude of the transition in correlated activity is larger, i.e. a stronger desynchronization occurs, when the animal perceives the stimulus correctly than when the animal fails to detect the stimulus. These results therefore show that a transition in synchronous firing is important for the detection of sensory stimuli. We hypothesize that the transition in synchrony reflects a change from loose and global neuronal interactions towards a finer temporal and spatial scale of neuronal interactions, and that such a change in neuronal interactions is required for figure-ground discrimination.     

Organization of Working Memory Processes in Monkeys: The Effects of a Dopamine Receptor Agonist

The effects of the dopamine receptor agonist agroclavin on cognitive processes associated with mechanisms of visual recognition and long-term and working (short-term) memory were studied in delayed visual differentiation and delayed spatial selection tasks in monkeys (rhesus macaques). Measurements made before and after p.o. pharmacological treatment with this agent were used to identify the p.o. dose (5 mg/kg) inducing a significant effect. The psychotropic effect of agroclavin, which induced cognitive dysfunction, was present in all the monkeys studied to one extent or another. Behavioral criteria were: the probability of correct solutions of the visual differentiation task, the probability of refusals to resolve the task, and the time taken for correct motor responses. Despite individual differences in these behavioral characteristics in monkeys, significant changes due to agroclavin were consistently evident in all animals. There was a reduction in the probability of correct solutions, due to worsening of the characteristics of short-term memory; most monkeys showed increases in the numbers of refusals to solve tasks and increases in the time for correct motor responses during these solutions. In fact, all monkeys showed no increases in the number of erroneous solutions in visual differentiation and spatial selection tasks without delays, though in most cases there were increases in the time taken for correct motor reactions and the number of refusals to solve tasks. Data were obtained indicating that the effect of agroclavin was not uniform with respect to different types of visual information. The possible structural-functional organization of processes underlying working memory is discussed on the basis of the conclusion that the behavioral characteristics studied here reflect different components of cognitive processes realized by structures with different functional properties and different locations.     

醋酸铅对雄性恒河猴生殖功能的影响

连续45d给予成年雄性恒河猴ig醋酸铅5和15mg·kg~(-1),结果血铅等铅接触指标发生明显改变;精子形态异常增多,活力下降;精液和睾丸铅含量,睾丸和附睾组织γ—GT和唾液酸的含量均显著增加,而SDH含量明显减少(P<0.05),丙二醛(MDA)和顶体蛋白水平改变无显著性意义,但表现出剂量-反应关系;睾丸超微结构可见,早期精子细胞顶体泡扩大,缺少顶体颗粒,支持细胞膜呈指状镶嵌,而精子数目变化无显著性意义;血清促滤泡素,促黄体素和睾酮水平无明显改变,提示下丘脑-垂体-性腺轴激素分泌机制和睾丸内精子发生过程尚无明显障碍,但成熟精子机能完善阻滞,受精力低下。     

马利兰对贫血恒河猴珠蛋白肽链合成速率的影响

用马利兰治疗三只贫血恒河猴,使其β类珠蛋白肽链合成述率(γ/γ β)及搞碱血红蛋白(HbF)升高。珠蛋白肽链合成速率升高时间较HbF水平的升高提前10天左右。γ/γ β升高幅度与马利兰的剂量及疗程长短有关。