Neonatal administration of beta-endorphin produces "chronic" insensitivity to thermal stimuli

Male and female rat pups were injected with β-endorphin, naloxone or a saline control solution during days 2–7 postnatally. At 90 days of age the rats were tested for analgesia with the tail flick test. Testing was conducted during the first 2 hours of the light and the dark cycle. In both sexes and during both phases of the light cycle rats treated with β-endorphin as infants evidenced a significant elevation in threshold for painful thermal stimuli. Early treatment with naloxone also resulted in elevated threshold for thermal stimuli. Administration of naloxone to these rats as adults did not reverse the analgesic effect. It was concluded that early exposure to β-endorphin results in permanent changes in behavior perhaps by altering the interaction of endogenous opiates with their binding sites during a ciritcal period of opiate receptor development.     

Ultrastructural and quantitative motoneuronal changes after ventral root avulsion favor early surgical repair

This study assesses qualitative and quantitative morphological changes that occur in motoneurons after ventral root avulsion. The motoneuronal perikaryal changes in the ventral horn of the cat's C7 cord segment were studied after survival times of 2, 8, 14, 30, 60 and 90 days. Generally, large motoneurons showed a light type of reaction, and the small ones either light or dark. In addition, neurons with a normal ultrastructural appearance were found. These latter are considered to be in a 'steady state', which may be associated with regenerative potency. All these types of neuron reactions were present at all survival times, but the number of cells marked by a specific reaction depends on the time of survival. Qualitative and quantitative evidence is given for cell death in 36% of the motoneuronal population between 2 and 14 days after avulsion. This reduction primarily concerns large, presumably alpha motoneurons with the light type reaction. Small, presumably gamma motoneurons become seriously affected after 14 days. These findings suggest that early surgical repair may have the better chances for clinical recovery.     

Characterization of the estrous cycle and reproductive traits of the aoudad (Ammotragus lervia) in captivity

In this study the estrous cycle of the aoudad has been analyzed and characterized for the first time, using non-invasive methods for tracking reproductive cyclicity. The duration of the estrous cycle is 23 days (range 16-32 days), with a luteal phase of 17 days (range 12-27 days) and an interluteal phase of 6 days (range 3-14 days). The estrous cycle did not differ between females, but it was affected by the time of the year. Intraindividual variation of the cycle was observed in one out of the nine individuals. The average hormone concentration values, the estrogen:progestogen ratio, as well as their minimum and maximum values for each interluteal and luteal phases of the estrous cycle, are shown. Interindividual differences found in these values were basically associated with age. Females tended to start their cycle when in the presence of an adult male. Anestrus was observed in study females except for the oldest (14 years old). Age and anestrus onset were correlated, with younger females starting earlier than the older ones. This study reveals that Ammotragus reproductive biology is more similar to that of Capra than Ovis, except for some endocrinological features.     

A biphasic excitability change in hindlimb motoneurons evoked by stimulation of the nucleus raphes magnus in the cat

1. The influence of electrical stimulation of the nucleus raphes magnus (RM) on spinal segmental systems were examined. 2. RM stimulation produced an initial increase and a subsequent suppression of the amplitude of both fiextor and extensor lumbar monosynaptic reflex potentials (MSRs). 3. Intracellular recordings were made from alpha-motoneurons of the common peroneal nerve (flexor) and the tibial nerve (extensor). RM stimulation evoked postsynaptic potentials with a time course similar to that of MSR facilitation. 4. RM stimulation inhibited the aggregate excitatory synaptic potential (EPSP) evoked by stimulation of group I afferent fibers without apparent changes in the motoneuronal membrane potential. 5. These data suggest that the RM-evoked biphasic effect on MSR consists of early facilitation due to EPSP, and late inhibition possibly due to presynaptic inhibition of group I afferent fibers.     

Morphology of the oviducts and endometria of cynomolgus macaques during the menstrual cycle

We sampled the reproductive tracts of 27 cynomolgus macaques during the menstrual cycle and correlated the cytologic changes in the oviductal epithelium with changes in the serum levels of estradiol (E2) and progesterone (P) and with the histology of the ovaries and the endometria. We identified an orderly sequence of changes in the oviductal epithelium from the early follicular to the late luteal phase, and we classified this sequence into eight stages, named as follows: preciliogenic, ciliogenic, ciliogenic-ciliated, ciliated-ciliogenic, ciliated-secretory, early regression, late regression and full regression. The preciliogenic and ciliogenic phases were coincident with menses and the early follicular phase. The ciliogenic-ciliated, ciliated-ciliogenic and ciliated-secretory phases during which the oviductal epithelium became progressively more differentiated were coincident, respectively, with the midfollicular, late follicular and periovulatory phases of the cycle. The early, late and full regression stages during which the epithelium became progressively more atrophied, deciliated and nonsecretory were coincident, respectively, with the early, mid and late luteal phases of the cycle. The cyclic changes in the endometrium of cynomolgus macaques were similar to those reported for the rhesus macaque.     

Combined antagonism of aminergic excitatory and amino acid inhibitory receptors in the XII nucleus abolishes REM sleep-like depression of hypoglossal motoneuronal activity

It is hypothesized that the suppression of motor activity (atonia) that occurs during REM sleep is caused by the combined inhibition of motoneurons by glycine or GABA and withdrawal of excitation mediated by serotonin and norepinephrine. However, it is not known whether these mechanisms can fully account for the atonia. In urethane-anesthetized, paralyzed and artificially ventilated rats, REM sleep-like episodes can be repeatedly elicited by microinjections of a cholinergic agonist, carbachol, into the dorsomedial pons. We used this model to determine whether microinjections of a combination of antagonists of serotonergic, adrenergic, GABA(A) and glycinergic receptors (methysergide, prazosin, bicuculline and strychnine) into the XII nucleus can abolish the carbachol-induced depression of XII motoneuronal activity. REM sleep-like episodes were elicited prior to, and at different times after, antagonist microinjections. In all six rats studied, the depression of XII motoneuronal activity did not occur when tested 30-60 min after the antagonists, whereas other characteristic features of the response (latency, duration, the appearance of hippocampal theta rhythm, activation of the cortical EEG, slowing of the respiratory rate) remained intact. The carbachol-induced depression partially recovered after 2-3 hours. We conclude that the REM sleep-like depression of XII motoneuronal activity can be fully accounted for by all or some of the following mechanisms: a withdrawal of motoneuronal excitation mediated by norepinephrine and serotonin and increased inhibition mediated by GABA and glycine.     

Effect of exhausting stretch-shortening cycle exercise on the time course of mechanical behaviour in the drop jump: possible role of muscle damage

The purpose of the present study was to investigate the effect of stretch-shortening-cycle-induced muscle damage on the time course of mechanical behaviour in the drop jump. Ten healthy male subjects performed submaximal stretch-shortening cycle (SSC) exercise on a special sledge apparatus. Exhaustion occurred on average within 3 min. A drop jump (DJ) test from a 50-cm height was performed before and immediately after the sledge exercise as well as 2 h, 2 days and 4 days later. The fatigue exercise showed relatively high blood lactate concentration [12.5 (SD 2.6) mmol x l(-1)] and an increase of serum creatine kinase (CK) activity delayed by 2 days [540 (SD 407) U x l(-1)]. The initial decline in the jump performance (before - immediately after) was related negatively to the early recovery in performance (immediately after 2 h) (P < 0.05). The early recovery of the knee joint moment at the end of stretch showed a negative correlation to the delayed decrease in DJ performance (2 h 2 days) (P < 0.01). Thus, the DJ performance showed an initial decline followed by an early recovery and a secondary decline. Both the initial decline and early recovery in the knee joint moment at the end of stretch were related to the corresponding initial (after 2 h) (P < 0.05) and secondary increases (2 h - 2 days) (P < 0.01) in CK. It is suggested that the early recovery as well as the initial decline in the knee joint function could depend on the degree of muscle damage. Delayed decrease in initial stiffness (2 h - 2 days) was negatively related to the corresponding changes in the knee joint angle at touch down in DJ (P < 0.001). These interactions would imply that the decrease in the stiffness regulation and the modulation of the prelanding motor control might be attributable to secondary muscle damage during 2 days after the SSC exercise. Therefore, it may be suggested that the changes in the DJ performance after the exhausting SSC exercise accompany the progress of muscle damage observed by the corresponding increase in serum CK concentration and the corresponding deterioration of stiffness regulation and motor control in DJ.     

Decline in the Recovery from Synaptic Depression in Heavier Aplysia Results from Decreased Serotonin-Induced Novel PKC Activation

The defensive withdrawal reflexes of Aplysia are important behaviors for protecting the animal from predation. Habituation and dishabituation allow for experience-dependent tuning of these reflexes and the mechanisms underlying these forms of behavioral plasticity involve changes in transmitter release from the sensory to motor neuron synapses through homosynaptic depression and the serotonin-mediated recovery from depression, respectively. Interestingly, dishabituation is reduced in older animals with no corresponding change in habituation. Here we show that the cultured sensory neurons of heavier animals (greater than 120g) that form synaptic connections with motor neurons have both reduced recovery from depression and reduced novel PKC Apl II activation with 5HT. The decrease in the recovery from depression correlated better with the size of the animal than the age of the animal. Much of this change in PKC activation and synaptic facilitation following depression can be rescued by direct activation of PKC Apl II with phorbol dibutyrate, suggesting a change in the signal transduction pathway upstream of PKC Apl II activation in the sensory neurons of larger animals.     

Cyclin dependent kinase inhibitors prevent apoptosis of postmitotic mouse motoneurons

Recent evidence suggests that apoptosis in post-mitotic neurons involves an aborted attempt of cells to re-enter the cell cycle which is characterized by increased expression of cyclins, such as cyclin D1, prior to death. However, such cyclins activation prior to apoptotic cell death remains controversial. Many neurological disorders are characterized by neuronal loss, particularly amyotrophic lateral sclerosis (ALS). ALS is a motoneuronal degenerative condition in which motoneuron loss could be due to an inappropriate return of these cells in the cell cycle. In the present study, we observed that deprivation of neurotrophic factor in purified motoneuron cultures induces an apoptotic pathway. After neurotrophic factor withdrawal, DAPI (4,6-diamidin-2-phenylindol dichlorohydrate) staining revealed the presence of nuclear condensation, DNA fragmentation, and perinuclear apoptotic body. Similarly, release of apoptotic microparticles and activation of caspases-3 and -9 were observed within the first hours following neurotrophic factor withdrawal. Next, we tested whether inhibition of cell cycle-related cyclin-dependent kinases (cdks) can prevent motoneuronal cell death. We showed that three cdk inhibitors, olomoucine, roscovitine and flavopiridol, suppress the death of motoneurons. Finally, we observed early increases in cyclin D1 and cyclin E expression after withdrawal of neurotrophic factors. These findings support the hypothesis that after removal of trophic support, post-mitotic neuronal cells die due to an attempt to re-enter the cell cycle in an uncoordinated and inappropriate manner.     

Characterization of expiratory intercostal activity to triangularis sterni in cats

Our purpose was to characterize activity of the intercostal nerve branch innervating the triangularis sterni muscle and the motoneuronal activities comprising this nerve discharge. In decerebrate, vagotomized, paralyzed, and ventilated cats, phasic triangularis sterni neural activity was evident in normocapnia. In most cats, activity did not commence until midexpiration. Activity then rose progressively to terminate at end expiration. Peak neural activities increased in parallel with phrenic activity in hypercapnia and fell in hypocapnia. The progressive increase in triangularis sterni neural activity within each respiratory cycle resulted from recruitment of motoneuronal activities throughout expiration. Once recruited, many motoneurons had a decrementing or constant discharge frequency. In hypercapnia, motoneuronal discharge frequencies increased, and additional activities were recruited. The number of active motoneurons and their discharge frequencies fell in hypocapnia. A similar pattern of motoneuronal activities and responses to stimuli was observed in cats with intact vagi. Factors are considered that may underlie the recruitment pattern of triangularis sterni motoneuronal activities and the inhibition of these in early expiration.     

Progressive adult-onset emphysema in transgenic mice expressing human MMP-1 in the lung

Mice with lung-specific expression of human matrix metalloproteinase-1 (MMP-1) develop emphysematous changes similar to those seen in smoking-induced emphysema in humans. Morphometric analyses of three transgenic lines [homozygous colony (Col) 34, Col 50, and Col 64] with varying temporal expression of MMP-1 were undertaken to determine the validity of this animal as a model of adult-onset emphysema. Line 50 mice, which have early expression of MMP-1 (14 days postconception), exhibited morphometric changes by 5 days of age. In contrast, homozygous line 34 and 64 with delayed expression (birth and 2 wk of age) were normal up until 4 wk of age when progressive changes in their mean linear intercept were first noted. In contrast, heterozygous mice from line 34 with lower transgene expression did not develop emphysema until 1 yr of age. The changes in mean linear intercept coincided with an increase in lung compliance. Emphysema in these mice was associated with decreased immunostaining for type III collagen within the alveolar septa. This study provides evidence that MMP-1 induces progressive adult-onset emphysema by the selective degradation of type III collagen within the alveolar wall.     

Uterus sympathetic nervous apparatus in sexual cycle dynamics in rats

Uterus sympathetic nervous apparatus in various phases of sexual cycle in rats was studied with the microspectral fluorescent method. The main part of nervous fibers in the form of perivascular plexus and terminals deviating from them are localized in myometrium. We suppose presence of reserve ("silent") nervous fibers in uterus which explains the inconstancy of their revealing in the organ. Catecholamines and serotonin are identified in varicose enlargements and intervaricose parts of nervous fibers by the way of microspectrofluorometry. Their concentration in probing places is characterized by high degree of linear correlation at all stages of sexual cycle. Maximal concentration of bioamines in most structural elements of uterus sympathetic nervous apparatus in detected in late diestrus. Stages of early and late estrus and proestrus are characterized by low levels of monoamines in adrenergic fibers. A number of reliable differences between bioamines saturation and spatial distribution density of nervous fibers in the neck and body of the womb are revealed.     

THE EVOLUTION OF TETRAPOD FEEDING BEHAVIOR: KINEMATIC HOMOLOGIES IN PREY TRANSPORT

One of the major features of the aquatic-to-terrestrial transition in vertebrate evolution was the change in the mechanism used to transport prey from the jaws to the throat. Primarily, vertebrates use hydraulic transport, but the transition to terrestrial life was accompanied by modifications of the hyobranchial apparatus that permit tongue-based transport. Despite an extensive data base on amniote feeding systems and mechanisms of intraoral prey transport, few data are available on the mechanism of prey transport in anamniote tetrapods. Transport cycles of four Ambystoma tigrinum (Amphibia) feeding on worms and crickets were filmed at 150 flames per second to produce quantitative profiles of the intraoral transport cycles for the two prey types. During the transport cycle the head and body remain stationary relative to the background: transport in Ambystoma tigrinum thus does not involve inertial movements of the head or body. Prey type had little effect on the kinematics of prey transport. The process of prey transport may be divided into four phases: preparatory, fast opening, closing, and recovery. The preparatory phase itself is divided into two parts: an extended segment that may include slight slow opening and a static phase prior to mouth opening where no change in gape occurs. The kinematic profile of transport in terrestrial salamanders is extremely similar to that used by fishes during hydraulic (aquatic) prey transport. We hypothesize that the distinct recovery and preparatory phases in the transport cycle of anamniote tetrapods are together homologous to the slow opening phases of the amniote cycle, and that during the evolution of terrestrial prey processing systems the primitive extended preparatory phase has become greatly compressed and incorporated into the amniote gape cycle.     

Disorganization of mitosis in HeLa cells by deuterium oxide

We assessed, by light and electron microscopy, the influence of deuterium oxide on the dynamics of mitosis and on the morphology of the mitotic apparatus in HeLa cells grown in vitro. A 2-h incubation of HeLa monolayers with low concentrations of D2O (1%-25%) in the medium increased the frequency of multipolar divisions up to 20 times the control level. Substitution of 10% and 25% D2O for H2O induced changes in the proportions of mitotic phases. These changes could be fully reversed to the control pattern after 1 h of recovery in non-deuterated medium. Fifty % D2O strongly inhibited, and 75% D2O blocked the cell cycle before prophase and at (pro-)metaphase. In cells treated with 50% D2O conspicuous morphological changes of the interphase chromatin as well as ultrastructural abnormalities of all mitotic phases were regularly observed. Overall, these results confirmed the antimitotic activity of deuterium oxide and revealed that it could also influence the cell cycle before mitosis. It is suggested that interference with diverse cellular constituents rather than a specific influence on microtubule turnover could be responsible for the disorganization of the cell cycle in HeLa cells by D2O.     

Functional morphology of the pharyngeal jaw apparatus in perciform fishes: An experimental analysis of the haemulidae

A new mechanical model for function of the pharyngeal jaw apparatus in generalized perciform fishes is developed from work with the family Haemulidae. The model is based on anatomical observations, patterns of muscle activity during feeding (electromyography), and the actions of directly stimulated muscles. The primary working stroke of the pharyngeal apparatus involves simultaneous upper jaw depression and retraction against a stabilized and elevating lower jaw. The working stroke is characterized by overlapping activity in most branchial muscles and is resolved into three phases. Four muscles (obliquus dorsalis 3, levator posterior, levator externus 3/4, and obliquus posterior) that act to depress the upper jaws become active in the first phase. Next, the retractor dorsalis, the only upper jaw retracting muscle, becomes active. Finally, there is activity in several muscles (transversus ventrales, pharyngocleithralis externus, pharyngohyoideus, and protractor pectoralis) that attach to the lower jaws. The combined effect of these muscles is to elevate and stabilize the lower jaws against the depressing and retracting upper jaws. The model identifies a novel mechanism of upper jaw depression, here proposed to be the primary component of the perciform pharyngeal jaw bite. The key to this mechanism is the joint between the epibranchial and toothed pharyngobranchial of arches 3 and 4. Dorsal rotation of epibranchials 3 and 4 about the insertion of the obliquus posterior depresses the lateral border of pharyngobranchials 3 and 4 (upper jaw). The obliquus dorsalis 3 muscle crosses the epibranchial-pharyngo-branchial joint in arches 3 and 4, and several additional muscles effect epibranchial rotation. Five upper jaw muscles cause upper jaw depression upon electrical stimulation: the obliquus dorsalis 3, levator posterior, levator externus 3/4, obliquus posterior, and transversus dorsalis. This result directly contradicts previous interpretations of function for the first three muscles. The presence of strong depression of the upper pharyngeal jaws explains the ability of many generalized perciform fishes to crush hard prey in their pharyngeal apparatus.     

Short-term synaptic plasticity in the dentate gyrus of monkeys

The hippocampus plays an important role in learning and memory. Synaptic plasticity in the hippocampus, short-term and long-term, is postulated to be a neural substrate of memory trace. Paired-pulse stimulation is a standard technique for evaluating a form of short-term synaptic plasticity in rodents. However, evidence is lacking for paired-pulse responses in the primate hippocampus. In the present study, we recorded paired-pulse responses in the dentate gyrus of monkeys while stimulating to the medial part of the perforant path at several inter-pulse intervals (IPIs) using low and high stimulus intensities. When the stimulus intensity was low, the first pulse produced early strong depression (at IPIs of 10-30 ms) and late slight depression (at IPIs of 100-1000 ms) of field excitatory postsynaptic potentials (fEPSPs) generated by the second pulse, interposing no depression IPIs (50-70 ms). When the stimulus intensity was high, fEPSPs generated by the second pulse were depressed by the first pulse at all IPIs except for the longest one (2000 ms). Population spikes (PSs) generated by the second pulse were completely blocked or strongly depressed at shorter IPIs (10-100 or 200 ms, respectively), while no depression or slight facilitation occurred at longer IPIs (500-2000 ms). Administration of diazepam slightly increased fEPSPs, while it decreased PSs produced by the first pulse. It also enhanced the facilitation of PSs produced by the second stimulation at longer IPIs. The present results, in comparison with previous studies using rodents, indicate that paired-pulse responses of fEPSPs in the monkey are basically similar to those of rodents, although paired-pulse responses of PSs in the monkey are more delayed than those in rodents and have a different sensitivity to diazepam.     

Ultrastructural Features of the Oral Region of Amicronucleate Paramecium tetraurelia in Autogamy1

ABSTRACT Amicronucleate Paramecium tetraurelia fails to develop an oral apparatus but resorbs the pre-existing one in the sexual cycle. Previous cytological studies have revealed the presence of a shallow, oral depression with a few scattered basal bodies after autogamy or conjugation. The present ultrastructural study of the ectoplasm beneath the oral depression revealed only the presence of a disorganized filamentous reticulum and small blocks of cytopharyngeal ribbons. In addition, beneath the oral depression, a large number of discoidal vesicles were found, similar to but larger in diameter than those normally associated with the cytopharynx of vegetative cells. The oral structures found in amicronucleates in autogamy might be remnants of the pre-existing oral apparatus, but the possibility that they were newly developed was not excluded. The morphogenetic interest of these structures was discussed. It is evident that amicronucleates in autogamy do not develop an extensive oral ultrastructural organization.     

Effects of prolonged administration of morphine on the estrus cycle of the rat

Ten female rats, of the age of three months, were treated for 24 days with increasing doses (10 mg/kg daily in the first week, 20 mg/kg in the second week, 30 mg/kg in the third week and 40 mg/kg in the last three days of treatment) of morphine acetate injected intra peritoneum, in order to cause a chronic intoxication (13). Five rats were utilized as controls. In all cases the vaginal smears was daily examined in order to evaluate the possible changes induced by the drug administration. The results obtained show that morphine produces important alterations in the estrous cycle of all the treated animals. In fact from the second day of treatment all animals had the cycle blocked in metaestrous. Afterwords a great variability occurred with a complete lack of estrous for the whole experimental period in five rats and very irregular succession and length of the phases into other ones. After the interruption of the treatment a resumption of the normal cycle was observed.     

Cyclic localization change of Golgi apparatus in Sertoli cells induced by mature spermatids in rats

Previously we reported that the intracellular localization of the Golgi apparatus of rat Sertoli cells changes during the seminiferous epithelial cycle, and that the cyclic changes seem to be correlated to specific generations of germ cells. To ascertain which generations of germ cells are responsible for the cyclic changes, we determined the relative volume of the Golgi apparatus within the basal, mid, and apical cytoplasm of Sertoli cells in testes with and without mature spermatids. In normal adult rats, the Golgi apparatus was usually localized exclusively in the basal cytoplasm, whereas at stages VII-IX it increased remarkably in mid and apical cytoplasm, with a concomitant decrease in the basal cytoplasm. In young adult testes without spermatids at steps 15-19 of spermiogenesis (2nd layer spermatids), the Golgi apparatus was localized in the basal cytoplasm throughout the seminiferous epithelial cycle. Orchiopexy maintained for 35 days following 60 days of cryptorchidism allowed germ cells to regenerate to spermatids at steps 1-14 of sperminogenesis (1st layer spermatids), but failed to change the intracellular localization of the Golgi apparatus in Sertoli cells. At 50 days after orchiopexy, when all generations of germ cells appeared in the tubules, the cyclic changes in localization of the Golgi apparatus were restored similar to those in normal adult testes. These findings indicate that the cyclic change in localization of the Golgi apparatus in Sertoli cells is evoked by the presence of 2nd layer spermatids.