Increased Acetylcholine Synthesis and Release in Brains of Cats with GM1 Gangliosidosis

Cholinergic processes were measured in motor cortex, hippocampus, and striatum of cats in the terminal stages of GM1 gangliosidosis and compared to those of control cats. The greatest difference observed was elevation in the rate of K+-stimulated release of acetylcholine (ACh) from brain slices prepared from affected cats. The K+-stimulated release of endogenous ACh was increased by 31-43% and of newly synthesized ACh by 19-80% in brain slices from different brain regions. All regions that were examined were affected but the greatest effects occurred in cortex. The rate of synthesis of ACh was elevated in cortical and hippocampal slices. Choline acetyltransferase activity in brain regions of cats with GM1 gangliosidosis was not significantly different from that in controls, whereas high-affinity choline transport in cortical synaptosomes was elevated. Muscarinic receptor binding sites were reduced in the cortex, hippocampus, and striatum of GM1 mutant cats, whereas the apparent affinity was not altered. These results indicate that there are major alterations of cholinergic function in the brains of cats with GM1 gangliosidosis.     

Taurine in the developing cat: Uptake and release in different brain areas

Taurine is an important modulator of neuronal activity in the immature brain. In kittens, taurine deficiency causes serious dysfunction in the cerebellar and cerebral visual cortex. The processes of taurine transport in vitro were now studied for the first time in different brain areas in developing and adult cats. The uptake of taurine consisted initially of two saturable components, high- and low-affinity, in synaptosomal preparations from the developing cerebral cortex and cerebellum, but the high-affinity uptake component completely disappeared during maturation. The release of both endogenous and preloaded labeled taurine from brain slices measured in a superfusion system was severalfold stimulated with a slow onset by depolarizing K⁺ (50 mM) concentrations. K⁺ stimulation released markedly more taurine from the cerebral cortex, cerebellum and brain stem in kittens than in adult cats. The responses were largest in the cerebellum. Both uptake and release of taurine are thus highly efficient in the brain of kittens and may be of significance in view of the vulnerability of cats to taurine deficiency.     

Changes in the membrane structure of the brain microsomes in cats with electrodes implanted in the inner ear

Using spin-labels it was shown that electrode implantation into the cats scala media resulted in structure reconstruction of microsome membranes of auditory zones in cats brain. Membrane fluidity increased but there was no change of surface potential. The changes of microviscosity were found during the first month after the implantation. Five months later the order parameter returned to the mean valve for cats in control group without electrodes.     

Neuropharmacologic analysis of the process of developing extinctive inhibition in the lobectomized cat

Pharmacological action on cholinergic and monoaminergic brain structures in the process of food-procuring reflex extinction was studied in intact and lobectomized cats. Growing stimulation of cholinergic structures of lobectomized animals caused consecutive behavioural changes similar to those appearing during development of active reaction of intact animals to cancellation of the reflex reinforcement. In both cases influences on monoaminergic systems produced analogous effects, but suppressing influence of haloperidol injection on food-procuring activity of lobectomized cats was significantly weakened. Conclusion is made that the development of active reaction of the animal to cancellation of food reinforcement is due to an increasing activation of brain cholinergic structures and consecutive activation of monoaminergic structures. Disturbance of extinction functions in lobectomized cats may be connected with disturbance of monoaminergic systems balance as a result of hyperactivity of dopaminergic structures.     

Dimethyl sulfoxide as a corrector of disorders of cerebral hemodynamics, oxygen and carbohydrate metabolism of the brain and lipid peroxidation in the early period after intracerebral hemorrhage

Intraperitoneal injection of DMSO (0.7 g/kg) in rats 1h after intracerebral hemorrhage prevented brain conjugated diens and fluorosciene products increase and limited cerebral ++anti-radical activity. In experiments on cats 1h after intracerebral hemorrhage intravenous infusion of DMSO (0.3 g/kg) for 30 min improved cerebral hemodynamic, oxygen and glucose metabolism; cats mortality was decreased.     

Motor activity and the content of neuroactive amino acids in brain tissues

The influence of forced motor activity (swimming) on quantitative shifts in neuroactive amino acids (GABA, glutamic and aspartic acids and glycine) was studied in brain tissues of rats and cerebrospinal fluid of cats in health and brain circulation disturbances. The data obtained point to the elevation of the content of amino acids in the brain and appearance of GABA in the cerebrospinal fluid during brain ischemia.     

Influence of halothane on control of breathing in intact and decerebrated cats

The effects of halothane anesthesia have been investigated in intact and in decerebrated cats. Pulmonary ventilation and breathing pattern were studied during room-air breathing, hypercapnia, and O2 inhalation. The following results have been demonstrated. First, halothane anesthesia does not modify pulmonary ventilation, but a tachypnea much more intense in intact than in decerebrated cats is observed. This indicates that halothane-induced tachypnea originates mainly in structures rostral to the brain stem. Second, decerebrated animals exhibit a breathing pattern and a ventilatory response to CO2 similar to those of intact conscious cats, suggesting that forebrain facilitatory and inhibitory influences on brain stem are cancelled out by decerebration. However, the tidal volume vs. inspiratory duration relationship observed in decerebrated cats differs from that in conscious cats. Finally, during halothane anesthesia, ventilatory response to CO2 is markedly depressed. Third, during O2 inhalation, except in decerebrated, anesthetized animals, ventilation is only slightly depressed. This suggests that central stimulatory effect of O2 is enhanced and/or that peripheral chemoreceptor drive is reduced.     

Hypercarnivory and the brain: protein requirements of cats reconsidered

The domestic hypercarnivores cat and mink have a higher protein requirement than other domestic mammals. This has been attributed to adaptation to a hypercarnivorous diet and subsequent loss of the ability to downregulate amino acid catabolism. A quantitative analysis of brain glucose requirements reveals that in cats on their natural diet, a significant proportion of protein must be diverted into gluconeogenesis to supply the brain. According to the model presented here, the high protein requirement of the domestic cat is the result of routing of amino acids into gluconeogenesis to supply the needs of the brain and other glucose-requiring tissues, resulting in oxidation of amino acid in excess of the rate predicted for a non-hypercarnivorous mammal of the same size. Thus, cats and other small hypercarnivores do not have a high protein requirement per se, but a high endogenous glucose demand that is met by obligatory amino acid-based gluconeogenesis. It is predicted that for hypercarnivorous mammals with the same degree of encephalisation, endogenous nitrogen losses increase with decreasing metabolic mass as a result of the allometric relationships of brain mass and brain metabolic rate with body mass, possibly imposing a lower limit for body mass in hypercarnivorous mammals.     

Effect of Age and Sex on the Acquisition of Immunity to Toxoplasmosis in Cats*

SYNOPSIS. The effects of age and sex of the cat on oocyst shedding, multiplication of Toxoplasma gondii in tissues of cats, and acquisition of immunity were investigated after oral inoculation of cats with Toxoplasma cysts. Twenty-five cats varying in age from 1 week to 39 months were killed 7-97 days after inoculation with T. gondii. Homogenates of brain, heart, mesenteric lymph nodes, retina, and blood from these cats were inoculated into mice to test for Toxoplasma infectivity. Toxoplasma was isolated more frequently and in higher titers in mice receiving inocula from cats of the youngest age group (1 week old). Toxoplasma gondii was isolated from tissues of only 2 of 21 cats older than 2 months (at the time of inoculation), although all of the animals shed oocysts within 1 week after ingesting the parasites. The number of oocysts shed varied among littermates of the same sex and between sexes. Generally, cats younger than 12 months shed more oocysts than older cats. The number of oocysts shed by older cats varied considerably; males generally shed more oocysts than the females. However, the numbers of cats examined were too small for statistical comparison. Nevertheless, the observations suggest that cats older than 12 months should not be used in experiments where numbers of oocysts shed is critical.     

A statistical analysis of the functional connections between the neurons of the visual and motor cortex in different forms of conditioned-reflex behavior]

In experiments on cats with elaboration of delayed alimentary operant reflexes to light organization was studied of interneuronal cortical connections. By means of cross-correlation analysis the dynamics of intra- and interstructural neuronal network was revealed at the level of cortical projections (visual and motor) of cats brain zones at three forms of behaviour: CR realization, in intersignal period with the presence and absence of operant movements. Depending on the forms of behaviour, predominance of "informational" or "motivational" interneuronal connections was observed.     

Asymmetry of the electroencephalographic manifestations of REM and slow-wave sleep in the cat

Studies were carried out on cats by bipolar electrodes implanted into symmetrical points of somatosensory cortical areas, caudate nuclei, hippocampus, lateral geniculate bodies, reticular formation of the midbrain after section of the half of midbrain tegmentum and commissural systems of the brain. Animals with sections usually have asymmetry of sleep EEG. The phenomenon is revealed of the coexistence of slow-wave and paradoxal sleep in different brain halves.     

Neuropharmacologic analysis of the dopamin-, cholin- and GABA-ergic systems of the brain in the organization of reflexes to time

Neurochemical mechanisms and structural-functional relations of conditioned reflex to time, temporal prognosing, and trace processes were studied in freely behaving intact cats and cats with lesions of the frontal cortex and the head of the caudate nucleus. It has been found that reactions to time are controlled mainly by cholinergic brain structures, temporal prognosing is controlled by dopaminergic mediation, and the trace phenomena--by GABA-ergic system. The data obtained and the methods applied may be used in analysis of some psychopathological symptoms such as desorientation in time, confabulatory confusion, mnestic disorders.     

Serendipity and the Siamese cat: the discovery that genes for coat and eye pigment affect the brain

One day in the late 1960s, Ray Guillery was examining brain sections through the visual thalamus of cats, and he recognized that the arrangement of layers in the lateral geniculate nucleus (LGN) of one cat was strangely abnormal. The cat was identified as a Siamese cat, one of a breed selected for its unusual coat color, with reduced pigment over much of the body and eyes. This chance observation and the recognition of its significance led to a broad-ranging series of investigations. These experiments showed that the lack of normal levels of pigment in the retina in Siamese cats (and other hypopigmented mammals) was the critical factor in the misdirection of many of the projections of the retina to the brain, the nature of the projection error, and the developmental consequences of the relay of the misdirected retinal inputs to visual cortex. As a result, we have a better understanding of how the brain forms proper connections and of the neural basis of visual problems in albino humans.     

Cat brain mucopolysaccharides and their in vivo hyaluronidase digestion

The average yield of mucopolysaccharides isolated from adult cat brain was 3.29 mg, representing 0.02 per cent of the wet wt. of brain tissue. The lipid-free dried brain was approximately 10 per cent of the wet brain tissue weight. Mucopolysaccharide fraction distributions and concentration ratios are presented. Chronic administration of testicular hyaluronidase to adult cats resulted in an advanced stage of neurological impairment, a decrease in hyaluronic acid to about 40 per cent of the control value, and an even slightly greater decrease in chondroitin sulphate. With limited hyaluronidase injections, neurological impairment was milder; mucopolysaccharide concentrations after four doses of hyaluronidase decreased to approximately the same level as in chronic experimental cats.     

Dietary Restriction Affects Neuronal Response Property and GABA Synthesis in the Primary Visual Cortex

Previous studies have reported inconsistent effects of dietary restriction (DR) on cortical inhibition. To clarify this issue, we examined the response properties of neurons in the primary visual cortex (V1) of DR and control groups of cats using in vivo extracellular single-unit recording techniques, and assessed the synthesis of inhibitory neurotransmitter GABA in the V1 of cats from both groups using immunohistochemical and Western blot techniques. Our results showed that the response of V1 neurons to visual stimuli was significantly modified by DR, as indicated by an enhanced selectivity for stimulus orientations and motion directions, decreased visually-evoked response, lowered spontaneous activity and increased signal-to-noise ratio in DR cats relative to control cats. Further, it was shown that, accompanied with these changes of neuronal responsiveness, GABA immunoreactivity and the expression of a key GABA-synthesizing enzyme GAD67 in the V1 were significantly increased by DR. These results demonstrate that DR may retard brain aging by increasing the intracortical inhibition effect and improve the function of visual cortical neurons in visual information processing. This DR-induced elevation of cortical inhibition may favor the brain in modulating energy expenditure based on food availability.     

Behavioural and cardiovascular responses to electrical stimulation of the medulla oblongata of the cat

Effects of stimulation of the nucleus tractus solitarii, the dorsal motor nucleus of the vagus, the nucleus reticularis paramedianus, and the nucleus cuneatus were studied in free-moving cats. Stimulation of the medullary nuclei that are known to be involved in the central nervous control of cardiovascular functions might activate preprogrammed motor responses such as licking and sniffing, and induce complex behavioural response patterns such as sleep or flight reaction. Moreover, both lever-pressing for rewarding brain stimulation, and eating in food deprived cats might be modulated by these stimulations. In a shuttle box the cats showed no tendency toward shuttling during stimulation, except the stimulation of the nucleus reticularis paramedianus which produced aversion. The cardiovascular and respiratory effects varied parallel with the behavioural responses. It is concluded that the medullary nuclei related to visceral functions are capable of affecting somatomotor behaviour either directly on the motor system, or by inducing complex response patterns in which somatomotor and visceral responses are integrated.     

Characteristics of the psychotropic spectrum of action of mebicar

Under group interaction in cats, a new Soviet tranquilizer mebicar eliminates fear-alarm induced by stimulatin of the emotiogenic zone of the hypothalamus. This action is not associated with myorelaxant or hypnotic action. Mebicar decreases the brain noradrenaline level, exerts no effect on the dopaminergic systems, increases the brain serotonin level, and does not elicit cholinolytic action.     

Immunohistochemical study on the distribution of serotonin-containing cell bodies in the brain stem of the dog

The distribution of serotonin-containing neurons in the brain of the dog was studied by use of PAP immunohistochemistry. The lower brain stem was endowed with extensively scattered serotonergic cell bodies, a large portion of which was located in the raphe nuclei. At the same time, prominent distribution of serotonergic neurons in lateral areas outside the raphe nuclei was also demonstrated. Our observations on the brain stem were, in principle, consistent with those on rats, cats and monkeys, with only minor differences.     

Anticonvulsant properties of the cerebrospinal fluid during activation of the antiepileptic system of the brain

Cerebrospinal fluid (CSF) was obtained after 30-40 sessions of daily electrical stimulation of the cat cerebellum vermis. The intraventricular injection of CSF (10 microliters) to Wistar rats increased the latent period of initial seizure manifestations, significantly reduced the number of animals with seizures and reduced the severity of seizures induced by korazol injection (40 mg/kg). Analogous seizure changes were observed in rats after intraventricular injection of CSF (10 microliters) from cats subject to 3-10 electroshock seizure fits. Intraventricular injection of CSF (250 microliters) obtained from cats after electroshock to cats with strychnine-induced epileptic foci in the brain cortex led to the suppression of the epileptic activity. The conclusion was made that different ways of antiepileptic system activation cause the accumulation of endogenous antiepileptic substances in CSF.     

Effect of exogenous catecholamines in the amygdala of a 'rage' cat.

Minute amounts of epinephrine or norepinephrine alter the behavior of 'rage' cats (prepared by ventromedial hypothalamotomy) when these substances are focally instilled into both amygdalae via chronic brain cannulae capped with a silastic membrane. Hyperactive defense reactions are replaced by lethargy and placidity. Similar injections of epinephrine or norepinephrine into the amygdalae of normally placid cats who had not been subjected to ventromedial hypothalamotomy did not appreciably alter their behavior.