Groups Of Adult Cats Research Articles

The effects of taurine depletion on bile acid composition and its amino acid‐conjugation in the bile of cats

AimThe most established effect of functional amino acid‐like compound taurine is the conjugation with bile acids. In addition, taurine ameliorates hypercholesterolemia through promotion of hepatic bile acid synthesis from cholesterol by enhancing of CYP7A1. On the other hand, the conjugations of bile acids with taurine as well as glycine and the biosynthesis of taurine are also promoted by bile acids through the nucleus farnesoid X receptor. These findings imply that there is an interactive relationship on the metabolism of taurine and bile acids. Contrary to rodents, the ability of taurine biosynthesis is very poor in humans, and therefore, the body pool of taurine in humans depends on the oral ingestion. Furthermore, the ratio of conjugation of taurine, but not glycine, with bile acids also depends on taurine ingestion. This study evaluated the influence of depletion by taurine non‐ingestion on the metabolism of bile acid in bile in cats with poor taurine‐synthesizing ability as in humans.MethodControl (N=4) and Depletion(N=6) groups of adult cats were fed the soy protein‐based diet containing 0.15% and 0% taurine, respectively, for 30 weeks. Thereafter, taurine in the serum and tissues and bile acids in the bile were measured by LC‐MS/MS system.ResultSerum taurine concentration in the Depletion group significantly decreased to one tenth compared to that in the Control group after the 2nd week, and was undetectable since the 4th week. After 30 weeks, taurine in the various tissues was depleted in the Depletion group. Over 99.5% of bile acids in the bile were conjugated with taurine in the Control group. In the Depletion group, taurine‐conjugated bile acids significantly decreased to 35.2%, and instead, unconjugated bile acids significantly increased to 62.9%. Bile acid concentration in the bile significantly decreased to approximately 40% compared to that in the Control group. Bile acid types in cats were same to those in humans. In the composition of bile acids, cholic acid (CA), deoxycholic acid (DCA), and chenodeoxycholic acids (CDCA) were 83%, 12%, and 5%, respectively, in the Control group. On the other hands, CA significantly increased to 98%, and DCA and CDCA significantly decreased to 0.6% and 1.2%, respectively, in the Depletion group.ConclusionTaurine depletion caused the decrease of taurine conjugated bile acids in the bile, and instead, the increase of unconjugated bile acids. Consequently, the level of bile acids significantly decreased and the composition has changed. These results suggested that the synthesis of bile acids in humans might be regulated by taurine ingestion through the direct effects of taurine or the state of taurine conjugation with bile acids.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Spontaneous firing rate changes in cat primary auditory cortex following long-term exposure to non-traumatic noise: Tinnitus without hearing loss?

Changes of neural activity in animal models have been correlated with tinnitus in humans. For instance, increased spontaneous firing rates (SFR), increased spontaneous neural synchrony, and cortical tonotopic map reorganization may underlie this phantom auditory percept. The aim of this study is to quantify the changes in SFR activity in the cat primary auditory cortex, after long-term exposure to different types of non-traumatic acoustic environments. For that purpose, four different groups of adult cats were exposed to moderate-level (~70dB SPL), behaviorally irrelevant sounds for several weeks to months, and their SFRs were compared with those in control cats. The sounds consisted of random multi-frequency tone pip ensembles with various bandwidths (2–4kHz, 4–20kHz, and a pair of third-octave bands centered at 4 and 16kHz), as well as a “factory noise”. Auditory brainstem response (ABR) thresholds, ABR wave 3 amplitudes at ~55 and 75dB SPL, and distortion product otoacoustic emission (DPOAE) amplitudes were unaffected by the exposure. However, we found that the SFR decreased within the exposure frequency range and increased outside the exposure range. This increased SFR for units with characteristic frequencies outside the exposure frequency range, which was slow to reverse after the exposure offset, suggests a mechanism for tinnitus in the absence of hearing loss.

Effects of passive, moderate-level sound exposure on the mature auditory cortex: Spectral edges, spectrotemporal density, and real-world noise

Persistent, passive exposure of adult cats to bandlimited tone pip ensembles or sharply-filtered white noise at moderate levels (∼70 dB SPL) leads to a long-term suppression of spontaneous and sound-evoked activity in the region(s) of primary auditory cortex (AI) normally tuned to the exposure spectrum, and to an enhancement of activity in one or more neighboring regions of AI, all in the apparent absence of hearing loss. Here, we first examined the effects of passive exposure to a more structured, real-world noise, consisting of a mix of power tool and construction sounds. This “factory noise” had less pronounced effects on adult cat AI than our previous random tone pip ensembles and white noise, and these effects appeared limited to the region of AI tuned to frequencies near the sharp factory noise cutoff at 16 kHz. To further investigate the role of sharp spectral edges in passive exposure-induced cortical plasticity, a second group of adult cats was exposed to a tone pip ensemble with a flat spectrum between 2 and 4 kHz and shallow cutoff slopes (12 dB/oct) on either side. Compared to our previous ensemble with the same power in the 2–4 kHz band but very steep slopes, exposure to the overall more intense, sloped stimulus had much weaker effects on AI. Finally, we explored the issue of exposure stimulus spectrotemporal density and found that low aggregate tone pip presentation rates of about one per second sufficed to induce changes in the adult AI similar to those characteristic of our previous, much denser exposures. These results are discussed in light of the putative mechanisms underlying exposure-induced auditory cortical plasticity, and the potential adverse consequences of working or living in moderately noisy environments.

Neuronal responses in cat primary auditory cortex to electrical cochlear stimulation: IV. Activation pattern for sinusoidal stimulation.

Patterns of threshold distributions for single-cycle sinusoidal electrical stimulation and single pulse electrical stimulation were compared in primary auditory cortex of the adult cat. Furthermore, the effects of auditory deprivation on these distributions were evaluated and compared across three groups of adult cats. Threshold distributions for single and multiple unit responses from the middle cortical layers were obtained on the ectosylvian gyrus in an acutely implanted animal; 2 wk after deafening and implantation (short-term group); and neonatally deafened animals implanted following 2-5 yr of deafness (long-term group). For all three cases, we observed similar patterns of circumscribed regions of low response thresholds in the region of primary auditory cortex (AI). A dorsal and a ventral region of low response thresholds were found separated by a narrow, anterior-posterior strip of elevated thresholds. The ventral low-threshold regions in the short-term group were cochleotopically arranged. By contrast, the dorsal region in the short-term animals and both low-threshold regions in long-term deafened animals maintained only weak cochleotopicity. Analysis of the spatial extent of the low-threshold regions revealed that the activated area for sinusoidal stimulation was smaller and more circumscribed than for pulsatile stimulation for both dorsal and ventral AI. The width of the high-threshold ridge that separated the dorsal and ventral low-threshold regions was greater for sinusoidal stimulation. Sinusoidal and pulsatile threshold behavior differed significantly for electrode configurations with low and high minimum thresholds. Differences in threshold behavior and cortical response distributions between the sinusoidal and pulsatile stimulation suggest that stimulus shape plays a significant role in the activation of cortical activity. Differences in the activation pattern for short-term and long-term deafness reflect deafness-induced reorganizational changes based on factors such as differences in excitatory and inhibitory balance that are affected by the stimulation parameters.

Characterization of a prolonged regenerative attempt by diffusely injured axons following traumatic brain injury in adult cat: a light and electron microscopic immunocytochemical study.

Traumatic brain injury in animals and humans is well known to cause axonal damage diffusely scattered throughout the brain without evidence of other brain parenchymal change. This observation has prompted some to posit that such damaged axons are well positioned to mount a regenerative attempt. The present study uses an immunocytochemical marker specific for regenerating neurites to explore this issue. Further, in an attempt to expedite and enhance any potential regenerative effort, this study evaluates the efficacy of intrathecally applied nerve growth factor. Three sets of experiments were performed in adult cats. One group of animals was subjected to moderate fluid percussion brain injury and followed for 7 or 14 days post injury, with the continuous intraventricular infusion of nerve growth factor delivered by implanted osmotic pumps. These animals were compared to a second group of time-matched, sham-operated animals receiving artificial cerebrospinal fluid infusion. To assess axonal damage immunohistochemical staining for the low molecular weight neurofilament subunit (NF-L) was carried out using an NR4 monoclonal antibody. To localize axons exhibiting a regenerative response immunohistochemical staining for the growth associated protein GAP43 was employed. In sham controls, at the light microscopic level NF-L-immunoreactive axonal swellings were numerous at 7 days, but by 14 days post injury their frequency declined markedly. In contrast, GAP43-immunoreactive, disconnected reactive axonal swellings were rarely observed at 7 days but were numerous at 14 days. Ultrastructural analysis at 14 days post injury of carefully matched sections revealed reactive axons demonstrating sprouting consistent with a regenerative effort. Analysis of tissue from animals of 14 days of survival indicated that supplementation with nerve growth factor did not appear to enhance the capacity of damaged brain axons to mount a regenerative attempt. Rather, it appears that regenerative efforts seen reflect a spontaneous response. A third group of adult cats, subjected to the same injury but not subjected to osmotic pump implantation, was allowed to survive for 22-28 days. Animals in this group also demonstrated GAP43 immunoreactivity in reactive axonal swellings in the brain stem. This study demonstrates that diffusely injured axons can mount a sustained regenerative attempt that is associated with a reorganization of their cytoskeleton and accompanied by an up-regulation of growth-associated proteins.

Misdirected regeneration of injured recurrent laryngeal nerve in the cat

Introduction: Misdirected regeneration (MR) frequently occurs following injury to the recurrent laryngeal nerve (RLN) resulting in neurotmesis or axonotmesis. Physiological and anatomic parameters involved in the functional recovery of the larynx following freezing injury or neurorrhaphy of the RLN were studied. A multi-facilitated approach is undertaken to clarify the functional abnormalities caused by the MR after recurrent laryngeal nerve injury. Materials and Methods: Three groups of adult cats were studied. These included controls, cats with recurrent laryngeal neurorrhaphy, and cats with recurrent laryngeal nerve freeze injuries. From 2 weeks to 9 months after the nerve injury, the animals were studied endoscopically and with electromyography (EMG). Using the same animal, the number and location of motoneurons supplying the ipsilateral posterior cricoarytenoid (PCA) muscle were examined with horseradish peroxidase (HRP). Animals were subsequently sacrificed to study the pattern of reinnervation. Results: Following neurorrhaphy all cats had vocal cord paralysis. After neurorrhaphy, effective motion function did not return in the affected vocal cord and it remained fixed in the paramedian position. Although EMG of the laryngeal muscles of the affected side showed interference voltage, the pattern of activities was markedly different from that of the unaffected side, and reciprocity among the laryngeal muscles was not restored. The number of PCA motoneurons recovered to the normal range, but a considerable number of neuronal bodies were dispersed outside the normal PCA area. This indicates misdirected reinnervation to the PCA muscle by motoneurons that originally served other laryngeal muscles. In the freezing injury, effective vocal cord movement finally recovered after 6 months. At this time, EMG showed a normal pattern, although a relatively small amount of misdirected neurons was observed. Discussion: Functional recovery of vocal cord motion does not occur following neurorrhaphy. Prominently disorganized arrangement of laryngeal motor neurons was observed in the horseradish peroxidase study. This suggests that inappropriate reinnervation develops in spite of reapproximation and suturing. Altered central organization of the motor nucleus is a significant pathogenic factor in the loss of laryngeal muscular coordination following recurrent laryngeal nerve lesions. The degree of recovery is related to the mechanism of injury.

Effects of arrhythmia-producing concentrations of digitoxin on mechanical performance of cat myocardium

Digitalis toxicity in vivo generally is recognized by the appearance of cardiac arrhythmias but in vitro by a decline in myocardial performance. To determine whether concentrations of digitoxin producing cardiac arrhythmias in intact animals also produce a decline in myocardial performance directly, three groups of adult cats were studied. One received digitoxin daily until arrhythmias developed (toxic group), the second sufficient digitoxin to produce an inotropic effect without arrhythmias (nontoxic group), and the third was untreated. Peak isometric force and maximal dF dt of isolated right ventricular papillary muscles were significantly greater in nontoxic muscles (3.9 ± 0.4 gm/mm 2 and 21.3 ± 1.7 gm/mm 2 · sec −1). Values in toxic muscles were similar to untreated ones (2.8 ± 0.6 gm/mm 2 and 19.0 ± 3.2 gm/mm 2 · sec −1). Acetylstrophanthidin (2 × 10 −8 M) resulted in an increase in peak force and max dF dt in nontoxic muscles, whereas myocardial performance changed minimally in untreated muscles and declined in 8 of 10 toxic muscles. We conclude that electrical and mechanical toxicity induced by digitoxin frequently coexist.

Single and combined lesions of the cat's thalamic mediodorsal nucleus and the mamillary bodies lead to severe deficits in the acquisition of an alternation task

The acquisition of a spatial alternation task was tested in five groups of adult cats. Two groups were used for control; one of them consisted of non-lesioned cats, the other of cats with chemical lesions (ibotenic acid) of the ventral tegmental area. The other three groups of cats received chemical lesions of the mediodorsal nucleus of the thalamus, the mamillary bodies, or of both structures together. Cats with lesions of the ventral tegmental area were non-significantly impaired in comparison to non-lesioned cats in the acquisition of the task. Cats with lesions of the mediodorsal nucleus, the mamillary bodies, or with combined lesions of both structures were significantly impaired, compared to the two control groups; among each other, however, their performance rates were similar. As none of the cats with single or combined lesions of the mamillary and the mediodorsal nuclei manifested observable abnormalities with respect to motor, motivational, or emotional behavior during their testing period, it is concluded that their - compared to the other two groups - inferior performance was due to a memory defect. As all three kinds of lesions resulted in a similar defect, it is suggested that the mamillary and the mediodorsal nuclei transmit information to one or more common target area(s), which is (are) dependent on information from either nucleus to operate effectively.

Dorsal root recurrent collaterals in young cats

The number of recurrent collaterals in the L5 dorsal root was compared in a group of young cats and a group of adult cats. There were significantly more recurrent collaterals in the young animals. This is taken as support for the ‘aberrant afferent’ hypothesis of recurrent collaterals.

A Developmental Study of the Sound Pressure Transformation by the Head of the Cat

The interaural intensity difference (IID) created by the imposition of a cat's body in a free sound field was measured in two age groups of kittens and one group of adult cats. For all animals significantly larger IIDs were obtained for high than for low frequency stimulation. The frequency at which peak IID occurred was higher for the younger group of kittens than for either the Old Kittens or the Adults. Above 4 kHz the Adults showed a marked variation of IID with azimuth, whilst the Young Kittens showed little variation of IID with azimuth at frequencies below 10 kHz. It was found that Adult-like IIDs are achieved before physical maturation is complete. The results are discussed with reference to the physiological development of sensory systems and the implications for a possible post-natal plasticity of the auditory system are examined.

Identification of cells or origin of non-primary afferents to the dorsal column nuclei of the cat.

In order to identify cells of origin in the spinal cord of non-primary afferents to the dorsal column nuclei (DCN), the retrograde transport of horseradish peroxidase (HRP) has been utilized in adult cats. 10 to 30% HRP was injected bilaterally (0.6 mul per side) in the dorsal medulla of nine cats. In most instances the spread of the injected enzyme extended a few millimeters rostrocaudally and infiltrated the DCN as well as other nuclei and fiber tracts. Labelled cells in these cases are numerous in the upper cervical, brachial and lumbosacral cord but are sparse in thoracic segments below T1. At upper cervical levels (C1-C4) HRP-positive neurons are distributed throughout the grey matter but are especially concentrated in the medial part of lamina VI. Cells projecting to the dorsal medulla are mainly localized in lamina IV and, more ventrally, along the medial border of the dorsal horn in the brachial and lumbosacral cord. Labelled cells at these levels are also scattered within lamina I and laminae VI through VII in cases in which the focus of the injection involved extensive portions of the medulla. From cases in which bilateral HRP injections were preceded by spinal tractotomy, it appears that the axons of at least the majority of labelled cells in lamina IV ascend in the ipsilateral dorsal quadrant of the spinal cord. In another group of adult cats, 0.1 to 0.25 mul of 30 to 50% HRP was injected unilaterally in the dorsal medulla at the level of, or rostral to, the obex. With these volumes of exogenous enzyme, an intense reaction product is largely confined within the limits of the DCN. Labelled cells in these cases are found almost exclusively in the medial part of lamina VI at upper cervical levels and, at brachial and lumbosacral levels, throughout lamina IV and medially in lamina V on the side of the cord ipsilateral to the injection. The results are discussed in relation to the organization of the dorsal horn ascending pathways with special reference to cells or origin of the spinocervical tract.

EFFECTS OF SINUS NERVE STIMULATION ON CAROTID BODY GLOMUS CELLS

The sinus nerve or sympathetic trunk was stimulated unilaterally in one group of adult cats or Syrian hamsters while in another group the sinus nerve or sympathetic trunk was cut unilaterally and the animals were given reserpine. In a third group, atropine was administered prior to sinus nerve stimulation. All tissues were processed for the detection of primary monoamines. The carotid bodies on the operated sides were compared with those on the unoperated sides of the same animal in order to determine if amine depletion occurred following the experimental procedures. After sinus nerve stimulation alone, the density of the granules in the glomus cells was decreased, but changes were not noted in the granules following sympathetic nerve stimulation. Sinus nerve stimulation after atropine administration resulted in no change in granule density. Sinus nerve transection followed by reserpine treatment resulted in a greater decrease in granule density on the unoperated than on the operated side. Transection of the sympathetic components to the carotid body followed by reserpine injections resulted in a decrease in granule density in the glomus cells on both the operated and unoperated sides. These results suggest that the sinus nerve must be intact for reserpine to exert an effect and that the sinus nerve may contain efferent fibers which modulate amine secretion.

Acinar-islet cells in the exocri pancreas of the adult cat.

Observations on a human pancreas in a case of the Zollinger-Ellison syndrome led us to postulate that secretin is capable of inducing nesidioblastosis (neoformation of islets). In order to test this hypothesis, a group of adult cats was given Pansecrin (Squibb secretin); a control group received normal saline. Acinar-islet cells containing in some cases both zymogen and islet-type secretory granules as well as the endoplasmic reticulum of acinar cells were seen in pancreases of secretin-treated cats. The islet-type secretory granule seen in acinar-islet cells resembled those of alpha-type islet cells.