Participation of hippocampal neurons on the stages of feeding behavior

Activity of 65 hippocampal single units was recorded during an instrumental feeding behaviour in three rabbits. Different neurons fire or change their spontaneous activity in one or more behavioural acts, which constitute the consecutive behaviour. In one or the other behavioural act single unit discharges occur both after and before some intermediate results. Participation of hippocampus in organization of the consecutive behaviour is discussed.     

Angiotensin II in the organization of rat feeding behavior

Intraventricular injection of angiotensin-II (100 ng) increased the latency period and decreased the amount of food intake in the hungry rats. Preliminary administration of saralasin (100 ng) blocked the inhibitory effect of angiotensin-II on food consumption. In contrast to the above mentioned intraperitoneal injection of angiotensin-II (10 ng/kg) 10 min before food and water admission results in the tendency to increase the food intake. And the same application of angiotensin-II 60 min before food and water admission increased by 49% of food intake in hungry rats. Saralasin (50 ng/kg) given prior to the angiotensin-II administration blocked the angiotensin-II effects. Moreover a significant decrease in the food intake was found after intraperitoneal injection of saralasin only. No significant changes in the drinking behavior in response to the intraventricular and intraperitoneal drugs administration were registered.     

Pentagastrin as a stimulator of immunogenesis

It has been shown that subcutaneous injection of pentagastrin to mice in doses 0.01-5 micrograms per animal during 10 days resulted in a considerable stimulation of the immune response to sheep red blood cells (SRBC). Pentagastrin in doses of 5 and 1 micrograms per animal was demonstrated to have the highest immunostimulating effect. These doses increased the production of IGM-antibody-forming cells 2.2-2.7-fold and produced a twofold elevation of the antibody titer. Pentagastrin did not influence the immune response to thymus independent Vi-antigen. The in vitro treatment of mouse bone marrow cells with pentagastrin (0.1 or 0.01 microgram/ml) increased the number of Thy-1 positive cells from 0 to 16-17%. Pentagastrin at a dose of 0.001 microgram/ml was not effective.     

Effect of hippocampal stimulation on the feeding behavior of cats

Influence of electrical stimulation (100 cps., 1.0 ms) of medial parts of dorsal and ventral hippocampus (field CA1), and the lateral parts of dorsal and posterior hippocampus (field CA3) on general behaviour, elaboration of instrumental and manifestation of delayed reactions was studied in chronic experiments on cats. Stimulation of medial parts of dorsal and ventral hippocampus elicited a reaction of orienting reflex type to natural stimuli. Stimulation of lateral parts of dorsal and posterior hippocampus evoked arrest reactions. Medial and lateral parts of hippocampus produced different influences on elaboration of conditioned reflexes. In the first case elaboration was possible, but developed slower, while in the second case the ability to learn during stimulation was completely lost due to development of arrest reaction. Stimulation of different parts of the hippocampus disturbed delayed reactions, reducing the number of correct responses.     

Identification of HGF-like protein as a novel neurotrophic factor for avian dorsal root ganglion sensory neurons

HGF-like protein (HLP) is a member of the hepatocyte growth factor (HGF) family. Although HGF is shown to have neurotrophic activities on many of CNS and PNS neurons, the role of HLP in the nervous system is poorly understood despite the knowledge that Ron/HLP receptor is expressed in embryonic neurons. Here we show that HGF but not HLP promotes neurite extension and migration emanating from chick embryonic day 9 (E9) dorsal root ganglia (DRG) explants in the presence of low levels of NGF, however, HLP does promote neurite extension and cellular migration from E15 chick DRG explants with low levels of NGF. Ron-Fc, a chimeric molecule composed of the extracellular domain of Ron fused with immunoglobulin Fc, eliminated activities of HLP, such as cellular migration and long neurite extension emanating from E15 DRG explants in the presence of NGF, but did not eliminate short neurites. These results suggested that promotion of long neurite extension and migration depends on activities of HLP through its receptor/Ron. Taken together, we propose that HLP may play an important role in chick sensory ganglia at relatively late stages of development. This is the first evidence that HLP functions as a neurotrophic factor.     

Significance of local synchronization and oscillatory processes of thalamic neurons in goal-directed human behavior

The time-frequency characteristics and interaction in the cell ensembles of the nonspecific (CM-Pf) and motor (Voi) thalamus were analyzed. Neuronal activity was registered by microelectrode technique during 18 stereotactic neurosurgery operations in spasmodic torticollis patients. The presentation of functionally significant verbal stimuli was accompanied by the emergence of short-term (0.5–1.5 s) local synchronization and stabilization of the oscillatory (3–6 Hz) activity in neighboring neurons of the nonspecific (CM-Pf) thalamus. These focuses of synchronized oscillatory neuronal activity were correlated with the moment of the greatest concentration of selective attention. A similar phenomenon of shortterm synchronization was observed in the motor (Voi) and nonspecific (CM-Pf) thalamus of the human brain during voluntary movements. Synchronization of neuronal activity occurred at the height of the implementation of the motor act, correlating with the maximum muscle tension, as well as in the aftereffect of the voluntary movement. In general, the findings suggest an important role of the local oscillations (3–6 Hz) and synchronization of thalamic neurons in the mechanisms of the relevant information transmission during goal-directed human behavior.     

Identification of neurons responsible for feeding behavior in the Drosophila brain

Drosophila melanogaster feeds mainly on rotten fruits,which contain many kinds of sugar.Thus,the sense of sweet taste has evolved to serve as a dominant regulator and driver of feeding behavior.Although several sugar receptors have been described,it remains poorly understood how the sensory input is transformed into an appetitive behavior.Here,we used a neural silencing approach to screen brain circuits,and identified neurons labeled by three Gal4 lines that modulate Drosophila feeding behavior.These three Gal4 lines labeled neurons mainly in the suboesophageal ganglia(SOG),which is considered to be the fly’s primary taste center.When we blocked the activity of these neurons,flies decreased their sugar consumption significantly.In contrast,activation of these neurons resulted in enhanced feeding behavior and increased food consumption not only towards sugar,but to an array of food sources.Moreover,upon neuronal activation,the flies demonstrated feeding behavior even in the absence of food,which suggests that neuronal activation can replace food as a stimulus for feeding behavior.These findings indicate that these Gal4-labeled neurons,which function downstream of sensory neurons and regulate feeding behavior towards different food sources is necessary in Drosophila feeding control.     

Effect of cortisol microiontophoresis on discharge time structure of dorsal hippocampal neurons in rabbits

The effect of microiontophoretic application of cortisol to single neurons of the dorsal hippocampus on the character of distribution of interspike intervals in their discharges was studied in chronic experiments on rabbits. Cortisol modified the time structure of regular and rhythmic discharges of hippocampal neurons. Regularization of discharges in the form of bursting activity appeared as the result of cortisol in cells with irregular spontaneous activity. Activity of more than half of the neurons, in which bursting discharges corresponded in frequency to the theta-rhythm, was intensified as a result of microapplication of cortisol. In neurons discharging complex spikes, in which under normal conditions a phenomenon of reduction of spike amplitude was observed within each burst, no definite rule as regards changes in the time structure of the discharges could be observed after administration of the hormone. It is suggested that cortisol plays a modulating role in mechanisms of generation of spike activity by hippocampal neurons.P. K. Anokhin Research Institute of Normal Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 13, No. 6, pp. 628–635, November–December, 1981.     

The interaction of mediators with protein synthesis processes in the visual cortex neurons in the goal-directed behavior of cats]

The chemical sensitivity was studied of the neurones of cats visual cortex at successive stages of food-procuring instrumental behaviour, formed in conditions of intraventricular administration of the blocker of protein synthesis the cyclohexamide. Animals with cyclohexamide had a low chemical sensitivity of the cortical neurones to microionophoretically applied solutions of acetylcholine and noradrenaline. In comparison with the intact animals, in animals with cyclohexamide the number of neurones reacting with change of the impulse activity at the stages of instrumental behaviour as well as the number of areactive cells, did not depend on the nature of the applied neurotransmitter.     

Asymmetry of movement direction as a tactic in the feeding behavior of rats

The sign and degree of spatial-motor asymmetry in rats were studied in conditions both of spontaneous or signalled choice in an U-maze and spontaneous multiple choice in a radial labyrinth. It was shown that during investigation of a new environment, motor asymmetry in rats was feebly expressed in all conditions of experiments, irrespective of the labyrinth scheme and experimental procedures. In the process of training, adequate behaviour was formed and in some conditions a distinctly expressed spatial asymmetry appeared, while in other cases it was absent. Apparently, while investigating an "unknown" situation (where rats can move rightwards and leftwards), the strategy of "displacement" is characteristic of them. Later the rate of asymmetry manifestation depends on concrete spatial and temporal characteristics of already "familiar" surroundings.     

Monocyte chemoattractant protein-1 functions as a neuromodulator in dorsal root ganglia neurons

It has previously been observed that expression of chemokine monocyte chemoattractant protein-1 (MCP-1/CC chemokine ligand 2 (CCL2)) and its receptor CC chemokine receptor 2 (CCR2) is up-regulated by dorsal root ganglion (DRG) neurons in association with rodent models of neuropathic pain. MCP-1 increases the excitability of nociceptive neurons after a peripheral nerve injury, while disruption of MCP-1/CCR2 signaling blocks the development of neuropathic pain, suggesting MCP-1 signaling is responsible for heightened pain sensitivity. To define the mechanisms of MCP-1 signaling in DRG, we studied intracellular processing, release, and receptor-mediated signaling of MCP-1 in DRG neurons. We found that in a focal demyelination model of neuropathic pain both MCP-1 and CCR2 were up-regulated by the same neurons including transient receptor potential vanilloid receptor subtype 1 (TRPV1) expressing nociceptors. MCP-1 expressed by DRG neurons was packaged into large dense-core vesicles whose release could be induced from the soma by depolarization in a Ca²⁺-dependent manner. Activation of CCR2 by MCP-1 could sensitize nociceptors via transactivation of transient receptor potential channels. Our results suggest that MCP-1 and CCR2, up-regulated by sensory neurons following peripheral nerve injury, might participate in neural signal processing which contributes to sustained excitability of primary afferent neurons.     

Activity of rabbit's neocortical and hippocampal neurons in orienting-exploratory behavior and freezing

By plotting autocorrelation histograms, the character of impulsation of neurons in bilateral derivations from cortical visual and somatosensory areas and hippocampal field CA1 was studied in rabbits during free behavior under the influences of emotional stimuli. During active orienting-exploratory reaction of rabbits, most cortical and hippocampal neurons manifested bursting discharges and theta-frequency oscillation (predominantly 4-5 Hz in cortex and 4-5, 6-7 in hyppocampus). During freezing, as compared with active locomotor reaction, the number of neurons with equiprobabilistic discharges increased; in impulsation of neurons with periodicity, the intensity of delta-frequency oscillation increased (predominantly 2-4 Hz) but theta-frequency oscillation decreased. The number of neurons with delta-frequency oscillation during freezing was greater then in calmly sitting rabbits.     

睫状神经营养因子对NO引起海马神经元毒性反应的影响

本研究采用原代培养大鼠海马神经元,观察睫状神经营养因子（ｃｉｌｉａｒｙ ｎｅｕｒｏｔｒｏｐｈｉｃ ｆａｃｔｏｒ,ＣＮＴＦ）对ＮＯ引起细胞毒性反应的影响。ＮＯ供体硝普钠与Ｓ－亚硝基－乙酰青霉胺,ＮＯＳ底物Ｌ－Ａｒｇ及钙载体ｉｏｎｏｍｙｃｉｎ,均可引起海马神经元存活率下降,ＬＤＨ漏出增加;提前２４ｈ给予不同浓度ＣＮＴＦ,均能提高神经元的存活率,减少ＬＤＨ漏出,其作用呈剂量依赖性。