Cat Forebrain Research Articles

Adenosine, prolonged wakefulness, and A1-activated NF-κB DNA binding in the basal forebrain of the rat

There is considerable evidence to suggest that adenosine is a modulator of behavioral state. Our previous reports showed that perfusion of adenosine into the basal forebrain decreased wakefulness. Furthermore, prolonged wakefulness resulted in increased levels of extracellular adenosine in the basal forebrain of cats and rats. However, the longer-term consequences of prolonged wakefulness and increased adenosine are largely unknown. We report here an increase in the DNA binding activity of the transcription factor, nuclear factor-kappa B (NF-kappaB) following 3 h of sustained wakefulness in the rat basal forebrain. Moreover, this treatment led to the appearance of the p65 subunit of NF-kappaB in the nucleus, as determined by western blot analysis of nuclear proteins. This contrasted with undetectable levels in the sleeping controls. A concomitant disappearance of I-kappaB in cytoplasm suggested the degradation of this inhibitor of NF-kappaB. In the acute in vitro basal forebrain slice preparation, perfusion of adenosine increased NF-kappaB DNA binding while pretreatment of the slices with the A1 adenosine receptor antagonist, cyclopentyl-1-3-dimethylxanthine, significantly reduced NF-kappaB DNA binding. These results are compatible with the hypothesis that increases in the levels of adenosine in the basal forebrain, that occur during prolonged wakefulness, act through an A1 adenosine receptor and a second messenger system to increase the activity of the transcription factor NF-kappaB. We further hypothesize that some of the long duration effects of prolonged wakefulness/sleep deprivation on performance and physiology, often termed 'sleep debt', might be mediated through adenosine and its activation of NF-kappaB, which is known to alter the expression of several behavioral state regulatory factors.

Neurokinin-1 expression and co-localization with glutamate and GABA in the hypothalamus of the cat

Recent behavioral studies using pharmacological techniques have demonstrated that the high affinity substance P (SP) receptor, neurokinin-1 receptor (NK-1), in the medial hypothalamus could be important in mediating defensive rage behavior in the cat. These observations prompted us to use molecular techniques to determine the distribution of NK-1 in the hypothalamus and in other regions of the forebrain relevant to the control of rage behavior. We cloned a 650 bp fragment of the cat NK-1 cDNA. Partial DNA sequence analyses of this fragment indicate 90% homology with the human cDNA. By in situ hybridization (ISH), we showed that NK-1 mRNA was localized in the cytoplasm but not nuclei of cat forebrain neurons. Furthermore, NK-1 mRNA was co-localized in neurons that displayed positive immunolabeling for glutamate or GABA. Moderate labeling was visualized in the anterior medial hypothalamus which receives significant SP input via the stria terminalis from the medial amygdala. Strong labeling was also observed in the basal amygdaloid complex. The functional significance of this labeling pattern is suggested from the observation that both the medial and basal complex of amygdala serve as powerful modulators of defensive rage behavior. Weaker labeling was seen over the posterior medial and lateral hypothalamus. The distribution of NK-1 in the hypothalamus was matched by that of SP-immunoreactive axons and pre-terminals that were observed in the hypothalamus. The overall findings provide anatomical evidence to show that the high affinity SP receptor, NK-1, is linked to glutamate and GABA neurons in the anterior medial hypothalamus and further suggests its likely role in the regulation of feline aggression.

The behavioral effects of the destruction of the magnocellular basal nucleus of the forebrain of cats.

Behavioral experiments were carried out in cats following methodology which simulates complexly organized, nonautomatized behavior with elements of generalization and abstraction. A conclusion was reached regarding the participation of this formation in the structural-functional support of complex integrative forms of activity, cognitive and gnostic processes, was reached on the basis of the results of the performance of test tasks by the animals with partial destruction of the magnocellular basal nucleus. The proposed mechanism of the involvement of the basal nucleus in gnostic and cognitive processes is the nonspecific support of the system of structures which participate directly in thinking and learning.

Expression of Fos protein in the cat forebrain induced by the electrical stimulation of tooth pulp.

Expression of Fos protein in the cat forebrain induced by the electrical stimulation of tooth pulp.

Induction of the c-fos proto-oncogene by electrical stimulation of tooth pulp in the cat forebrain

Induction of the c-fos proto-oncogene by electrical stimulation of tooth pulp in the cat forebrain

Dopamine- and DOPA-immunoreactive neurons in the cat forebrain with reference to tyrosine hydroxylase-immunohistochemistry

The distribution of cell bodies containing immunoreactivities to dopamine (DA),l-3,4-dihydroxyphenylalanine (DOPA) and tyrosine hydroxylase (TH) was studied immunohistochemically in the cat forebrain especially in the hypothalamus with or without intraventricular administration of colchicine. In normal cats, DA-immunoreactive (IR) neurons, whose intensity of immunostainings was variable from one to another, were localized exclusively in the hypothalamus and showed a distribution pattern similar to that of TH-IR ones. They were distributed in the posterior, dorsal and periventricular hypothalamic areas. Arcuate cells showed no or very weak DA-immunoreactivity. Weak to intense DOPA-IR cells were distributed in a similar manner to DA-IR ones but were far smaller in number. In colchicine-treated animals, DA- and DOPA-immunoreactivities were enhanced particularly in arcuate and dorsal hypothalamic cells. A cluster composed of small DA- and DOPA-IR cells was identified in the area ventral to the mamillothalamic tract equivalent to rat A13c TH-IR cell group. Colchicine treatment enabled us to visualize a large number of TH-IR perikarya in the medial and lateral preoptic areas, anterior commissure nucleus, basal forebrain, area closely related to the organum vasculosum laminae terminalis, and some in the bed nucleus of the stria terminalis as has been reported in other species. However, virtually none of these cells contained detectable DA- and DOPA-immunoreactivities.

Imaging of the degeneration of neurons and their processes in rat or cat brain by 45CaCl2 autoradiography or 55CoCl2 positron emission tomography.

The possibility of using radiolabeled divalent cations to visualize nerve cell degeneration in the brain was investigated after intoxication with neurotoxins. At different survival times after the intracerebral injection of kainic acid or 6-hydroxydopamine, autoradiographs were made from brain sections of rats that had received 45CaCl2 intravenously 24 h before death. Brain sections, adjacent to those used for autoradiography, of the 6-hydroxydopamine-treated rats were used for histofluorescence of catecholamines to check the neurochemical effect of the treatment. These experiments show that radioactive Ca accumulates in brain tissue during a particular phase of degeneration. Not only could degenerating cell bodies be traced by 45Ca autoradiography, but also degenerating nerve terminals in the striato-nigral and nigro-striatal projection systems. In positron emission tomography (PET) studies, 55CoCl2 was used as a marker for Ca2+. Unilateral lesions of the cat forebrain, produced by kainic acid, could be imaged in vivo by PET with 55CoCl2. PET with this radiolabel may provide diagnostic potentials for human neurodegenerative disorders.

Prostaglandin formation in feline cerebral microvessels: effect of endotoxin and interleukin-1.

The pathogenesis of fever involves the appearance of interleukin-1 in the circulation in response to appropriate noxae (e.g., endotoxin) and subsequent generation of prostaglandin E2 in the CNS. The present study was undertaken to determine whether the cerebral microvasculature may function as a source of the fever-producing prostaglandin E2. Microvessels, consisting predominantly of capillaries, were isolated from the cat forebrain by selective sieving and glass bead elutriation. Preparations contained enzymes for the synthesis of 6-keto-prostaglandin F1 alpha (hence prostaglandin I2), prostaglandin E2, and possibly prostaglandin F2 alpha. No prostaglandin D2 was detected, nor was evidence obtained for the formation of 6-keto-prostaglandin E1. Intact microvessels released prostaglandin E2 and 6-keto-prostaglandin F1 alpha under basal conditions, the latter compound exceeding the former by about sevenfold. Endotoxin stimulated prostaglandin E2 release without significantly altering 6-keto-prostaglandin F1 alpha release. In contrast, monocyte-derived interleukin-1 reduced the release of both compounds, while recombinant interleukin-1 was ineffective. Endotoxin stimulation is likely directed on the cleavage of substrate arachidonic acid from precursor lipids, while inhibition from monocyte-derived interleukin-1 is ascribed to the presence of an interfering substance. This substance, like endotoxin, is thought to act prior to the cyclooxygenase cascade and its identity remains to be ascertained. We conclude that the cerebral microvasculature does not lend itself to an active role in the genesis of fever by being the site at which blood-borne interleukin-1 promotes prostaglandin E2 synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Sleep suppression following kainic acid-induced lesions of the basal forebrain

We have described elsewhere neurons in the ventral basal forebrain of cats that have elevated discharge rates during sleep and during transitions from waking to sleep, yet have comparatively low discharge rates during waking. These sleep-active neurons may mediate the hypnogenic properties of the basal forebrain. To further evaluate their role in the control of sleep, we examined the effects of basal forebrain lesions produced by microinjections of the relatively cell-selective neurotoxin, kainic acid, on sleep. Lesions were made bilaterally in two regions that contain high densities of sleep-active neurons: the horizontal limb of the diagonal bands of Broca and the lateral preoptic area-substantia innominata. Twelve-hour polygraph recordings were made before and at various intervals after basal forebrain damage in a total of eight cats. The lesions resulted in reduced time spent in deep, nonrapid eye-movement sleep and REM sleep, and increased time spent awake. These abnormalities persisted through 6 to 7 weeks postlesion. Reductions in deep non-REM sleep were due to decreases in bout number, particularly in the number of extended deep non-REM episodes (i.e., those >5 min in duration). The number of REM sleep episodes was also significantly reduced. The average duration of epochs of waking was elevated throughout the postlesion period. Thus, in the postlesion period, cats exhibited an impaired ability to initiate and maintain consolidated periods of sleep, particularly of deeper sleep stages. Lesions were also associated with reduced EEG spindling during sleep. These results are consistent with our hypothesis that sleep-active neurons are a component of a basal forebrain sleep- and EEG-regulating mechanism.

ACTH-immunoreactive neurons and their projections in the cat forebrain

The organization of adrenocorticotropin (ACTH)-immunoreactive (IR) cell bodies and fibers in the cat forebrain is described. ACTH-IR cell bodies are found only in and around the arcuate nucleus of the hypothalamus (ARH). They are not detected elsewhere even after pretreatment with colchicine. ACTH-IR fibers are present in discrete areas of the hypothalamus, the septo-limbic areas and in the paraventricular thalamic nucleus. Complete electrolytic lesions of the ARH destroy ACTH-IR cell bodies as well as fibers in all parts of the brain. These results suggest that, in the cat forebrain, the ARH is the only source of ACTH-IR fibers.

Polysensory properties of the horizontal limb of the nucleus of the diagonal band in the cat forebrain

Polysensory properties of the horizontal limb of the nucleus of the diagonal band in the cat forebrain

Sleep-related neuronal discharge in the basal forebrain of cats

Although evidence suggests that the basal forebrain contains a hypnogenic mechanism, putative sleep-promoting neural elements within this area have not been identified. We examined basal forebrain neuronal activity during waking, non-rapid-eye-movement (NREM) sleep, REM sleep and various transition states. Based on state-related discharge rates, 3 cell types were defined. Thirty-nine of 83 cells were classified as waking-active, i.e. waking discharge rates were 2 times NREM sleep rates. Twenty-three of 82 cells were classified as state-indifferent (waking and NREM rates differed by a factor of < 2). NREM sleep discharge rates of the remaining 20 cells were > 2 times waking rates. These were labeled sleep-active cells. Discharge rates of these cells during epochs of alert waking were low, averaging < 1 spike/s. Maximal discharge rates occured during NREM sleep, averaging 9.44 spike/s. Increased discharge of sleep-active cells anticipated sleep onset; cells had an average discharge rate of 6.60 spike/s during transitions between waking and NREM sleep. Sleep-active cells were confined to the ventral basal forebrain, in the horizontal limb of the diagonal bands of Broca, substantia innominata, entopeduncular nucleus and ventral globus pallidus. These areas overlap, in part, with those where chemical, thermal and electrical stimulations evoke sleep, and where lesions suppress sleep. Based on location and discharge pattern, we consider sleep-active cells candidates for mediating some of the sleep-promoting functions of the basal forebrain.

Cerebral microvessels contain A β2-adrenergic receptor

Cerebral microvessels isolated from cat forebrain contain a specific β-adrenergic-sensitive adenylate cyclase. Among various compounds tested, the most potent activator of enzyme activity is isoproterenol (k a = 1.4 × 10 −7M), followed in order by epinephrine (k a= 1.5 × 10 −6M), norepinephrine (k a= 1.4 × 10 −5M) and phenylephrine (k a> 3 × 10 −4M). Isoproterenol-stimulated enzyme activity is blocked by propranolol (k i= 2.4 × 10 −9M, IPS 339 (k i= 4 × 10 −9M), H35/25 (k i = 1.2 × 10 −7M), atenolol (k i= 5.9 × 10 −6M) and practolol (k i= 1.8 × 10 −5M). These agonist and antagonist properties are quite similar to those demonstrated by β 2-adrenergic receptors and β 2-stimulated adenylate cyclase present in other tissues and indicate that the majority of adenylate cyclase-associated adrenergic receptors in cerebral microvessels are β 2. The findings are relevant to physiological studies of cerebral blood flow and vascular permeability.

Horseradish peroxidase-positive neurons of nonspecific thalamic nuclei projecting to the primary somatosensory cortex in cats

The morphology and topography of neurons whose axons form the nonspecific thalamic input in the primary somatosensory area were studied in the cat forebrain by the retrograde axonal horseradish peroxidase transport method. Stained cells were found in the dorsolateral part of the nucleus ventralis anterior, and were diffusely distributed in the nucleus centralis, lateralis, the lateral part of the nucleus dorsalis medialis, and the dorsal part of the centrum medianum. In the nucleus paracentralis only solitary, palely stained neurons were detected. Cells stained with horse-radish peroxidase were multipolar, triangular, or fusiform. The results are evidence that besides the ventrobasal complex, the nonspecific nuclei of the diencephalon also project into the somatosensory cortex. This indicates the existence of multiple afferent thalamic inputs into the somatic cortex.

Actin-like filaments in synaptosomes detected by heavy meromyosin binding

We have prepared cat forebrain synaptosomes in order to investigate the presence of actin-like proteins. First, actin-like filaments were demonstrated using a heavy meromyosin binding technique. Decorated filaments form networks inside the synaptosomes and are frequently seen in relation to membranes and synaptic vesicles. Second, using SDS-polyacrylamide gel electrophoresis, a band corresponding to actin appears to be one of the major constituents of synaptosomal fractions; this confirms the work of Fine and his coworkers. The significance of actin-like filaments in relation to axoplasmic transport is briefly discussed.

D-aspartate oxidase activity in extracts of mammalian central nervous tissue.

Abstract— d‐Aspartate oxidase activity has been measured in water extracts of acetone powders prepared from cat forebrain, cerebellum and spinal cord, rat brain, hog brain and sheep brain stem, and compared with that found in rabbit and cat kidney. The results suggest that the brain enzyme has very similar properties to the n‐aspartate oxidase (d‐aspartate: oxygen oxidorcductase (deaminating), EC 1.4.3.1) of kidney. Crude extracts (ammonium sulphate fractions of water extracts of acetone powders) displayed little activity without added FAD. FMN could not replace FAD. With oxygen as electron acceptor, the enzyme oxidized d‐aspartate much more rapidly than d‐glutamate, and displayed quite high activities with N‐substituted derivatives of d‐aspartate as substrates. Those amino acids susceptible to oxidation by d‐amino acid oxidase were not oxidized by the d‐aspartate oxidase. The regional distribution of the d‐aspartate oxidase activity within the CNS differed from that of d‐amino acid oxidase. As has been previously observed for kidney d‐aspartate oxidase activity, dicarboxylic acids competitively inhibited this enzymic activity in brain extracts, while sodium benzoate and sodium barbitone, inhibitors of d‐amino acid oxidase, were without effect.

Responses of neurones in the cat's visual cerebral cortex to relative movement of patterns.

1. We have investigated the responses of single neurones in the visual cerebral cortex of the unanaesthetized, isolated cat's forebrain to excitation of one retina with patterned light. The responses of twenty-six cells to the relative movement of two patterns in the visual field have been recorded.2. We used several forms of relative movement for stimulation, but all of them involved a change in the separation of two parallel and straight light-dark edges.3. Responses to this form of stimulation were compared with the responses of the same cells to simple movement, that is, movement of the same patterns without change of distance between their borders.4. All cells showed a response to relative movement that differed from their response to simple movement.5. The time-locked phasic response differed in 54% of the cells tested. Of cells responding in this way, 83% of tests produced an increased phasic response.6. Relative movement brought about changes in the mean frequency of discharge in 96% of the cells tested. 82% of these cells responded with an increased rate of firing.7. Movement relative to a coarse background pattern affected more neurones and produced a greater change in their behaviour than did movement relative to a fine-grained pattern.8. The neurones tested represented the central part of the visual field (0-10 degrees ); while all were affected by relative movement, those representing points furthest from the optic axis appeared to be most susceptible (we found no correlation between size of receptive field and distance from the optic axis).