Anatomical distribution of NPY‐like immunoreactivity in the domestic chick brain (Gallus domesticus)

Neuropeptide Y‐immunoreactive (NPY‐ir) fibers and neurons in the brain of the domestic chick (Gallus domesticus) were described using an immunohistochemical technique. NPY‐ir neurons were seen in the lobus parolfactorius; hyperstriatum, neostriatum, paleostriatum, and archistriatum; hippocampal and parahippocampal areas; dorsolateral corticoid area; piriform cortex; two thalamic areas contiguous to the n. rotundus; n. dorsolateralis anterior thalami, pars lateralis, and pars magnocellularis; n. periventricularis hypothalami; n. paraventricularis magnocellularis; regio lateralis hypothalami; n. infundibuli; inner zone of the median eminence; dorsal and lateral portions of the n. opticus basalis; n. raphes; and n. reticularis paramedianus. NPY‐ir fibers were seen throughout the entire chick brain, but were more abundant in the hypothalamus where they formed networks and pathways. They were also observed in some circumventricular organs. The anatomical data of the present study regarding the distribution of NPY ir in the chick brain, together with the physiological findings of other studies, suggest that NPY plays a key role in the regulation of the neuroendocrine, vegetative, and sensory systems of birds by acting as a neuromodulator and/or neurotransmitter. Anat Rec 263:186–201, 2001. © 2001 Wiley‐Liss, Inc.     

The distribution of NPY-like immunoreactivity in the chameleon brain

The distribution of neuropeptide Y (NPY) immunoreactivity was studied in the brain of the chameleon. Cell bodies and fibers displaying NPY-like immunoreactivity were widely dispersed throughout the brain and at the highest density in the telencephalon and diencephalon. Immunolabeled cell bodies were numerous in the medial and dorsomedial cortex and in the dorsal ventricular ridge, while the striatum and basal telencephalon only contained sparsely scattered NPY-positive somata. Immunopositive neurons were densely distributed in the dorsal thalamus (particularly in the perirotundal belt), the area triangularis, the nucleus geniculatus lateralis pars dorsalis, the periventricular hypothalamus and the medial eminence. In the pretectum, NPY-immunoreactive cell bodies were limited to the nucleus posterodorsalis, while in the mesencephalon immunolabeled somata were found in the stratum album centrale of the optic tectum and in the substantia nigra. Immunopositive fibers and terminals were particularly dense in the dorsomedial cortex, the periventricular hypothalamus, the nuclei accumbens, suprachiasmaticus and griseus tectalis, in the substantia nigra and in the torus semicircularis. These findings show that the NPY system in the chameleon has the same basic organization as in other vertebrate species, and indicate that this peptide could be also implicated in the regulation of several aspects of cerebral functions. In addition, and of particular interest, is the observation of numerous NPY-immunoreactive neurons and fibers in several visual nuclei, suggesting an important involvement of this substance in the visual function. Accepted: 22 August 2000     

Sleep in the domestic hen (Gallus domesticus)

Electrophysiological recordings were made of five closely observed hens, all permanently implanted with both EEG and EMG electrodes. Five behavioural postures were distinguished and percentages of wakefulness, sleep and presumably paradoxical sleep (PS) were determined during the third and sixth hour of the dark period. Substantial agreement was generally found between behaviour and sleep with the exception of sitting or standing motionless with at least one eye open. During two thirds of this behavioural posture, the EEG showed large amplitude slow waves undistinguishable from slow wave sleep. Characteristics of PS were determined: periods were short, whereas its percentage increased during the night. Furthermore, EMG atonia was never found. An all night recording was made, and delta activity (2-5 Hz) was filtered and plotted against time for three of the hens. A significant decrease in delta activity across the night was found. Differences and similarities between sleep in hens and in mammals are discussed. Although large similarities exist it is concluded that some properties of birds' sleep make it unique and are a challenge for further study.     

Neurotensin-like immunoreactivity in the brain of the chicken, Gallus domesticus

The distribution of neurons containing neurotensin in the central nervous system of the chicken was studied immunohistochemically. The majority of the neurotensin-immunoreactive (-ir) cell bodies were located in the hypothalamus. Extensive groups of labelled perikarya were found in the hypothalamic periventricular nucleus and in the magnocellular periventricular nucleus. In addition, ir-perikarya were scattered throughout the lateral hypothalamic area and in the ventromedial hypothalamic nucleus. The only extrahypothalamic site of ir-perikarya was in the region immediately under the lateral forebrain bundle. Immunoreactive fibres were detected in the hippocampus, the parahippocampal area, the hypothalamus, the region of the tractus corticohabenular and corticoseptal tracts, the median eminence, the region above the posterior commissure and in the intercollicular nucleus. The distribution pattern of the neurotensin-ir neurons suggests that neurotensin-like peptides are involved in the hypophysiotropic functions.     

Comparative distribution of NADPH-diaphorase activity and tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the domestic chicken (Gallus domesticus)

We described the distribution of NADPH-diaphorase-containing neurons in relation to tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the chicken. In the diencephalon, both markers were found in the lateral hypothalamus, dorsal hypothalamic area, hypothalamic periventricular nucleus, paraventricular nucleus and mamillary area. A close examination showed that the fine distribution of these markers differed slightly, so that they were never observed in the same neurons. In the mesencephalon, NADPH-diaphorase and tyrosine hydroxylase immunoreactivity were found in the ventral pedunculopontine area (nucleus tegmenti pedunculopontinus pars compacta, adjacent areas surrounding the quintofrontal tract and the nucleus mesencephalicus profundus ventralis), the coeruleus complex (locus coeruleus, ventral and dorsal subcoeruleus nuclei), the ventral tegmental area and the central gray. The majority of these neurons contained either diaphorase or tyrosine hydroxylase. Nevertheless, in a few cases both markers appeared to colocalize in the same neuron, typically in large perikarya of the ventral pedunculopontine area.     

The light and electron microscopic characterisation of identified striato-ventrotegmental projection neurons in the domestic chick (Gallus domesticus)

A major projection of the medial striatum (lobus parolfactorius, LPO) of birds is the striato-ventrotegmental pathway projecting to the area ventralis tegmentalis. In the present study, we investigated the morphology and connectivity of striato-ventrotegmental neurons in the medial LPO. The neurons were identified by injecting the fluorescent retrograde tracer fast blue (FB) into the area ventralis tegmentalis. FB-labelled neurons in the LPO were targeted and iontophoretically injected with lucifer yellow (LY) in paraformaldehyde fixed slices. The fluorescent LY label in the filled neurons was then photoconverted, and the ultrastructure of cells was investigated. According to our results, the soma of striato-ventrotegmental neurons is rich in organelles, in particular rough and smooth endoplasmic reticula and they possess a large, unindented and slightly eccentric nucleus. The LY-labelled cells possess relatively few, sparsely spiny dendrites, and represent a type of medium-sized spiny projection neuron characteristic of the striata of birds. Axospinous synapses on the labelled cells are asymmetric and correspond morphologically to the glutamatergic excitatory type of terminals described previously in the LPO. Both symmetric and asymmetric axodendritic and axosomatic synapses were detected. Some symmetric synapses were GABA immunolabelled, whereas some asymmetric synapses were immunopositive to glutamate. Axon collaterals of labelled cells formed symmetric or asymmetric axodendritic synapses. Direct contact without interposing glial processes was observed between one of the FB-labelled neurons and an adjacent neuronal soma. There was also a microneuron attached to one of the labelled cells, which we identified as a neurogliaform 'dwarf' cell.     

Olfaction and behavioral modification in domestic chicks (Gallus domesticus)

Olfactory responsiveness in the female domestic chick was examined in a series of experiments. Individually-housed chicks preferred the familiar soiled substrate from their own home box to that soiled by a strange conspecific and to clean wood litter when placed in an otherwise novel Y maze. An artificial odorant present during the development of group-reared chicks subsequently proved attractive in an otherwise novel and potentially frightening situation. Chicks reared with one of two aromatic oils subsequently discriminated between them and preferred the familiar oil when both were present in the test box. The preferences are likely acquired because naive, one-day-old chicks reacted similarly to wood litter treated with either water or oil. Presence of a familiar rearing odor also reduced fear of a novel open field. In contrast to controls, chicks whose nostrils were blocked prior to rearing with an aromatic oil showed no subsequent preference for this odorant. The present results suggest that domestic chicks can regulate their behavior in response to olfactory cues though trigeminal chemoreception may also be involved.     

The distribution of primary afferents to the cochlear nuclei in the domestic hen (Gallus domesticus).

The normal anatomy of the three cochlear nuclei in the hen, the nucleus laminaris, the nucleus angularis and the nucleus magnocellularis is described. Following lesions of the cochlear nerve, all three nuclei are shown to receive primary cochlear fibers (silver impregnation methods). The part of nucleus laminaris which consists of a ventral convex sheet of cells is shown to receive cochlear nerve fibers from both ears, the nerve fibers from the ipsilateral ear terminating dorsal to the cell sheet while contralateral nerve fibers terminate ventral to the nerve cells. The cochlear ganglion cells projecting to the nucleus laminaris are apparently situated in other parts of the ganglion that the cells projecting to the nucleus angularis and magnocellularis. The findings are discussed in the light of known data on the organization and function of the cochlear nuclei in birds.     

Antibody production suppressed in the domestic fowl (Gallus domesticus) by zinc deficiency

Fowls maintained on a zinc-deficient diet from hatching and immunised either by intraperitoneal injections of bovine serum albumin (BSA) or by a combination of ocular drops and intraperitoneal injections showed no antibody response as judged by immunoelectrophoresis and immuno-fluorescence, whereas birds on a zinc-sufficient diet had serum antibody and anti-BSA cells in the Harderian gland, Peyer's patches, spleen and thymus. The localisation of immunoglobulins did npt differ between control and deficient birds except in the bursa of Fabricius where follicle-associated epithelium of deficient fowls stained for immunoglobulins, especially IgA, whereas in sections from control birds these cells remained unstained.     

Density of arteriovenous anastomoses in some skin areas of the domestic fowl (Gallus domesticus)

The vascularity and the density of arteriovenous anastomoses (AVAs) were studied in the skin of the domestic fowl by using vascular injections and histological sections. The density of AVAs and associated blood vessels were low in the wattles and in the thoracic skin (five to 23 AVAs per cm2 and five to 14 AVAs per cm2, respectively), whereas the eyelids were highly vascular and contained many AVAs (170-172 AVAs per cm2). It is suggested that the blood vessels in the eyelids are important in the temperature regulation of the eye and that AVAs in the thoracic skin may contribute to the control of blood flow through the brood patch.     

Cytokines and chemokines in postovulatory follicle regression of domestic chicken (Gallus gallus domesticus)

The mechanism of postovulatory follicle (POF) regression in birds is still poorly understood. In the current study, expression of IL-1beta, IL-6, GM-CSF, IFN-gamma, IL-2, IL-4, IL-13, chCXCLi2, chCCLi2, chCCLi4, chCCLi7, IL-10 and TGF-beta2 mRNAs was estimated in regressing POF by semi-quantitative RT-PCR. In addition, the changes in immune cell population, histological and apoptotic changes were also studied in regressing POF. The expression of cytokines (IL-1beta, IL-6, IL-10 and TGF-beta2) and chemokines (chCXCLi2, chCCLi2, chCCLi4 and chCCLi7) was upregulated in POFs, suggesting a role for these molecules in tissue regression. The histological findings suggested a significant infiltration of immune cells, especially heterophils, lymphocytes and macrophages, into the regressing POF. The flow cytometry analysis of lymphocyte subpopulations revealed that CD3(+), CD4(+), CD8(+) and Bu-1(+) lymphocytes were significantly increased during this regression. The significant up-regulation of chemokines might have attracted the immune cells during POF regression. The percentage of apoptotic cells was significantly increased during the regression of POF. The up-regulation of IL-1beta, IL-6, IL-10 and TGF-beta2 and down-regulation of GM-CSF might have induced apoptosis during the POF regression. However, expression of IFN-gamma, IL-2, IL-4 and IL-13 was not significantly altered during POF regression. In conclusion, cytokines appear to play an important role in the regression of POF in chicken. Furthermore, the regression of chicken POF seems to be an inflammatory event similar to luteolysis of the mammalian corpus luteum.     

Effects of thyroxine and temperature manipulations upon the hatching of chick embryos (Gallus domesticus)

Thyroxine levels within chick embryos (Gallus domesticus) and incubation temperature were manipulated late in development in order to determine those events most proximal to the time of hatching that are both necessary and sufficient for the appearance of the hatched state. Events recorded include the time of breathing initiation, changes in breathing rate, time of puncture of the chorioallantoic membrane and changes in rate of loss of yolk sac material. It was found that a certain level of thyroxine is necessary for an animal to hatch, that breathing and puncture of the chorioallantoic membrane are necessary but not sufficient to predict the occurrence of hatching, and that a change in rate of loss of yolk sac material during the last 18 hr prior to hatching is sufficient to predict the occurrence of hatching. The explanatory hypothesis offered is that the endogenous increase in thyroxine levels acting via increased metabolic rates is necessary and sufficient for the animals to hatch.     

反复低氧对小鼠脑内神经肽Y免疫反应活性的影响

目的:观察反复低氧对小鼠脑内神经肽Y(NPY)免疫反应活性的影响。方法:昆明小鼠40只随机分为对照组、低氧1次(H₁)组、低氧2次(H₂)组、低氧3次(H₃)组和低氧4次(H₄)组。对低氧各组动物分别行不同次数的反复低氧。各组动物脑内NPY的免疫反应活性采用放射免疫测定法测定。结果:小鼠对低氧的标准耐受时间随反复低氧次数的增加而显著增加。经1次低氧和2次低氧后小鼠脑内NPY的免疫反应活性明显提高,分别为正常对照组的145.5%±3.2%和147.3%±2.5%(P＜0.01);而低氧3次后则降到正常对照水平。结论:反复低氧通过预适应能显著提高小鼠对低氧的耐受性,并可诱导小鼠脑内NPY免疫反应活性在预适应形成的早期一过性地上升。     

The effect of craniokinesis on the middle ear of domestic chickens (Gallus gallus domesticus)

The avian middle ear differs from that of mammalians and contains a tympanic membrane, one ossicle (bony columella and cartilaginous extra‐columella), some ligaments and one muscle. The rim of the eardrum (closing the middle ear cavity) is connected to the neurocranium and, by means of a broad ligament, to the otic process of the quadrate. Due to the limited number of components in the avian middle ear, the possibilities of attenuating the conduction of sound seem to be limited to activity of the stapedius muscle. We investigate to what extent craniokinesis may impact the components of the middle ear because of the connection of the eardrum to the movable quadrate. The quadrate is a part of the beak suspension and plays an important role in craniokinesis. Micro‐computed tomography was used to visualize morphology and the effect of craniokinesis on the middle ear in the domestic chicken (Gallus gallus domesticus). Both hens and roosters are considered because of their difference in vocalization capacity. It is hypothesized that effects, if present, of craniokinesis on the middle ear will be greater in roosters because of their louder vocalization. Maximal lower jaw depression was comparable for hens and roosters (respectively 34.1 ± 2.6° and 32.7 ± 2.5°). There is no overlap in ranges of maximal upper jaw elevation between the sexes (respectively 12.7 ± 2.5° and 18.5 ± 3.8°). Frontal rotation about the transversal quadrato‐squamosal, and inward rotation about the squamosal‐mandibular axes of the quadrate were both considered to be greater in roosters (respectively 15.4 ± 2.8° and 11.1 ± 2.5°). These quadrate rotations did not affect the columellar position or orientation. In hens, an influence of the quadrate movements on the shape of the eardrum could not be detected either; however, craniokinesis caused slight stretching of the eardrum towards the caudal rim of the otic process of the quadrate. In roosters, an inward displacement of the conical tip of the tympanic membrane of 0.378 ± 0.21 mm, as a result of craniokinesis, was observed. This is linked to a flattening and slackening of the eardrum. These changes most likely go along with a deformation of the extra‐columella. Generally, in birds, larger beak opening is related to the intensity of vocalization. The coupling between larger maximal upper jaw lifting in roosters and the slackening of the eardrum suggest the presence of a passive sound attenuation mechanism during self‐vocalization.