Neuropeptide Y and maternal behavior in the female native Thai chicken

Maternal care behaviors in birds include incubation and rearing behaviors. During incubating period, the hens stop laying and eating less due to food restriction as a natural fasting when compared with the rearing hens, resulting in low production of eggs and chicks. Neuropeptide Y (NPY), a neurotransmitter/neuromodulator, is very well known to be involved in food intake regulation in birds and mammals. The objective of this study is to elucidate the association between NPY and maternal behaviors in the female native Thai chicken. The distributions of NPY-immunoreactive (-ir) neurons and fibers in the brain of the incubating (INC), nest-deprived (ND), and replaced-egg-with-chicks (REC) hens at day 6 were determined utilizing immunohistochemistry technique. The results revealed that the distributions of NPY-ir neurons and fibers were observed within the septalis lateralis, nucleus rotundus, and nucleus dorsolateralis anterior thalami, with predominantly located within the the nucleus paraventricularis magnocellularis (PVN). NPY-ir fibers were located throughout the brain and the densest NPY-ir fibers were distributed in a discrete region lying close to the ventriculus tertius (third ventricle) through the hypothalamus. Changes in the number of NPY-ir neurons within the PVN of the INC, ND, and REC hens were compared at different time points (at days 6 and 14). Interestingly, the number of NPY-ir neurons within the PVN was significantly higher (P < 0.05) in the INC hens when compared with those of the ND and REC hens at day 14 but not day 6. In addition, the number of NPY-ir neurons within the PVN of the INC hens was significantly increased (P < 0.05) from day 6 to day 14 but not the ND and REC hens. These results indicated, for the first time, the asscociation between NPY and maternal behaviors in the femle native Thai chicken. Change in the number of NPY-ir neurons within the PVN during the transition from incubating to rearing behavior suggested the possible role of NPY in the regulation of the maternal behaviors in this equatorial species. In addition, the native Thai chicken might be an excellent animal model for the study of this phenomenon.     

A proposed conceptual reorganization of the basal ganglia and telencephalon.

A reordering of priorities applied to the criteria for grouping neuronal populations suggests a simpler conceptual organization of the basal ganglia and telencephalon than that currently in general use. The proposed scheme reduces the emphasis of the obvious geographical divisions imposed by the major white matter bundles and the cerebral ventricle, and emphasizes instead such criteria as a common internal histology, similar input-output patterns and characteristic neurotransmitters.By these reordered criteria, almost the entire telencephalon can be subdivided into three concentric tiers. The outermost tier (tier I) encompasses the structures derived embryologically from the pallium, the neocortex and the allocortex. The second tier (tier II) includes the caudate nucleus, the putamen, the nucleus accumbens septi and parts of the olfactory tubercle. The third tier (tier III) is composed of the external pallidal segment, the internal paltidal segment, the nondopaminergic part of the substantia nigra, and perhaps also parts of the substantial innominata.It is suggested that while many characteristics of the telencephalon and basal ganglia lend themselves to subdivision into ‘sensory’, ‘motor’, ‘associational’ and ‘limbic’ sectors, at least some features of organization appear to transgress such distinctions. The proposed reorganization does not deny the existence of such classical functional and anatomical subdivisions but focuses attention instead on two distinct telencephalic outflow systems each of which appears to serve overlapping and widespread parts of the telecephalon. One outflow system leaves the structures in tier I to influence monosynaptically the diencephalon, mesencephalon, pons, medulla or even the spinal cord, while the other outflow system follows a polysynaptic route with at least two intermediate synapses, the first between the tier I and tier II neurons and a second between the tier II and tier III neurons.Some implications of this perspective perhaps useful to the physiologist, pathologist and clinician are discussed.     

Thalamic commissural connections in the cat

The high-affinity of [3H]gamma-aminobutyric acid (GABA) to GABAA receptors and [3H]baclofen to GABAB receptors were studied in the cerebellum of pyridoxine-deficient rats and compared to pyridoxine-supplemented controls. There was a significant increase in the maximal binding (Bmax) of both GABAA and GABAB receptors with no significant difference in their binding affinities (Kd). The changes observed suggest a supersensitivity of GABAA and GABAB receptors which seems to correlate negatively with the concentration of GABA in the cerebellum of pyridoxine-deficient rats.     

Patterns of activity in pigeon brain's visual relays as revealed by the [14C]2-deoxyglucose method

The [¹⁴C]2-deoxyglucose method was used for autoradiographic mapping of functional activity in the pigeon visual system. In awake animals with one eye covered heavy labeling occurred in most of the known areas receiving projections from the exposed eye.In both the retino-tecto-rotundo-ectostriatal pathway and the retino-thalamo-hyperstriatal pathway higher centers were asymmetrically labeled. Labeling was more symmetrical, however, in the hyperstriatum which receives a bilateral projection from the visual dorsolateral thalamus. The activity was higher in the rostral hyperstriatum contralaterally, in the caudal hyperstriatum ipsilaterally to the exposed eye. The density within the labeled area was patchy in the rostral part. Heavy symmetrical labeling was observed in animals with both eyes exposed. In pigeons with both eyes covered some visual centers were still heavily labeled. Centers of the auditory system were labeled too. Plugging of one ear resulted in asymmetrical labeling in auditory projections.The results are largely consistent with what is known about neuronal pathways from the retina and so it seems to be justified to interpret the patterns of labeling in terms of local energy metabolism that reflects functional activity.     

Interaction between neuropeptide Y immunoreactive neurons and galanin immunoreactive neurons in the brain of the masu salmon, Oncorhynchus masou

We investigated the immunohistochemical localization of neuropeptide Y (NPY) and galanin (GAL) in the brain of the masu salmon Oncorhynchus masou in order to clarify the interaction between these neuropeptide hormones in the brain. NPY-immunoreactive (ir) cell bodies were observed in the ventral and lateral regions of the ventral telencephalon (Vv and Vl, respectively), and in the dorsolateral midbrain tegmentum. NPY-ir fibers were observed throughout the brain, mainly in the ventral telencephalon, hypothalamus, optic tectum, and midbrain. GAL-ir cell bodies were observed in the nucleus preopticus parvicellularis anterioris (PPa) and the ventral zone of the periventricular hypothalamus (Hv). Both GAL-ir and NPY-ir fibers were observed throughout the brain. Furthermore, we examined the interaction between the NPY neurons and GAL neurons by performing double-staining immunohistochemistry. Some GAL-ir fibers were in close contact with the NPY-ir cell bodies in the Vv and Vl. In addition, some NPY-ir fibers were in close contact with the GAL-ir cell bodies in the PPa and Hv. These findings suggest that reciprocal connections exist between the NPY neurons and GAL neurons in the brain of the masu salmon.     

Differential roles of hypothalamic serotonin receptor subtypes in the regulation of prolactin secretion in the turkey hen

In the turkey, exogenous serotonin (5-hydroxytryptamine, 5-HT) increases prolactin (PRL) secretion by acting through the dopaminergic (DAergic) system. In the present study, infusion of the 5-HT_2C receptor agonist, (R)(−)-DOI hydrochloride (DOI), into the third ventricle stimulates PRL secretion, whereas the 5-HT_1A receptor agonist, (+/−)-8-OH-DPAT hydrobromide (DPAT), inhibits PRL secretion. Using the immediate-early gene, c-fos, as an indicator of neuronal activity, in situ hybridization histochemistry showed preferential c-fos co-localization within tyrosine hydroxylase immunoreactive neurons (the rate limiting enzyme in DA synthesis) in the areas of the nucleus preopticus medialis (POM) and the nucleus premammillaris (PMM), in response to DPAT and DOI, respectively. To clarify the involvement of 5-HT_1A and 5-HT_2C receptors in PRL regulation, their mRNA expression was determined on hypothalamic tissue sections from birds in different reproductive stages. A significant difference in 5-HT_1A receptor was observed, with the POM of hypoprolactinemic short day and photorefractory birds showing the highest expression. 5-HT_2C receptors mRNA did not change during the reproductive cycle. The data presented support the notion that DA neurons in the PMM and POM mediate the stimulatory and inhibitory effects of 5-HT, respectively, on PRL secretion and the 5-HTergic system can both stimulate and inhibit PRL secretion.     

The influence of chronic lithium administration on deafferentation-induced cellular changes in the chick cochlear nucleus

The avian brainstem serves as a useful model system to address the question of how afferent activity influences viability of target neurons. Approximately 20-30% of neurons in the chick cochlear nucleus, nucleus magnocellularis (NM) die following deafferentation (i.e. deafness produced by cochlea removal). Previous studies have identified cellular events that occur within hours following cochlea removal, which are thought to lead to the ultimate death of NM neurons. We have recently shown that chronic lithium treatment increases neuronal survival following deafferentation. To assess where in the cell death cascade lithium is having its effect, we evaluated some of the early deafferentation-induced cellular changes in NM neurons. Lithium did not affect deafferentation-induced changes that occur across the entire population of NM neurons. There were still deafferentation-induced increases in intracellular calcium concentrations and early changes in the ribosomes, as indicated by Y10b immunolabeling. Lithium did, however, affect changes that are believed to be indicative of the subpopulation of NM neurons that will eventually die. Ribosomes recovered in all of the deafferented NM neurons (as assessed by Y10b labeling) by 10 h following cochlea removal in subjects pretreated with lithium, while a subpopulation of the NM neurons in saline-treated subjects showed dramatic reduction in Y10b labeling at that time. Lithium treatment also prevented the robust upregulation of b cell leukemia/lymphoma-2 (Bcl-2) mRNA that is observed in a subpopulation of deafferented NM neurons 6 h following cochlea removal.     

Development of the delay lines in the nucleus laminaris of the chicken embryo revealed by optical imaging

One strategy in localizing a sound source in the azimuthal plane is the comparison of arrival times of sound stimuli at the two ears. The processing of interaural time differences (ITDs) in the auditory brainstem was suggested by the Jeffress model in 1948. In chicks, binaural neurons in the nucleus laminaris (NL) receive input from both ipsilateral and contralateral nucleus magnocellularis (NM) neurons, with the axons of the latter acting as delay lines. A given neuron in the NL responds maximally to coinciding input from both NM neurons. To achieve maximum resolution of sound localization in the NL, the conduction velocity along these delay lines must be precisely tuned. Here, we examined the development of this velocity between embryonic days (E)12 and E18. Our optical imaging approach visualizes the contralateral delay lines along almost the complete NL of the chicken embryo. Optical imaging with the voltage-sensitive dye RH 795 showed no significant differences in the velocity between E12 and E15, but a significant increase from E15 to E18, at both 21 °C and 35 °C. Surprisingly, at 21 °C the conduction velocity in the dorso–lateral part of the NL was significantly higher compared to the situation in the ventro–medial part. The observed development in contralateral conduction velocity may be due to a developmental increase in myelination of the NM axons. Indeed, antibody staining against myelin-associated glycoprotein (α-MAG) showed no myelination of the NM axon branches within the NL at E12 and E15. On the other hand, a clear α-MAG immunoreactivity occurred at E18. Our results therefore describe the developmental physiological properties of the delay line in the chicken embryo.     

Topographic organization of the cerebellothalamic projections in the rat. An autoradiographic study

The topographical organization of the subnuclear projections towards the thalamus was studied with autographic methods in adult Wistar rats. The four cerebellar deep nuclei give rise to projections to the ventral region of the rostral thalamus. Most of the fibers end contralaterally, according to a topographical pattern; however, some fibers from each of the cerebellar nuclei recross the midline at the thalamic level and terminate ipsilaterally, within regions symmetric to those receiving the densest contralateral projection. These ipsilateral cerebellothalamic components arise in decreasing order from the caudal nucleus lateralis, the ventrocaudal nucleus medialis and the nucleus interpositus, respectively. The projections of the nucleus lateralis directed to the contralateral thalamus are topographically organized. (1) Within the nucleus ventralis lateralis, the rostral and caudal parts of the cerebellar nucleus lateralis project respectively to rostral and caudal regions; lateral and medial zones of the nucleus lateralis project, respectively, to medial and central aspects of the nucleus ventralis lateralis. (2) The nucleus ventralis medialis and particularly its caudal portion appears to receive the bulk of its afferents from the ventromedial portion of the nucleus lateralis including the "subnucleus lateralis parvocellularis". (3) The nucleus centralis lateralis receives fibers from most parts of the nucleus lateralis including the "dorsolateral hump". (4) The nucleus interpositus anterior projects to the dorsomedial aspect of the rostral nucleus ventralis lateralis. In the latter nucleus, the ventrolateral aspect of the central region receives projections in cases in which the nucleus interpositus posterior is largely involved. A particular emphasis is put on the different projections from the various subnuclear regions of the lateral nucleus. A comparison is attempted with the situation in the primates, particularly with regard to the question of the parvocellular subdivision of the lateral nucleus.     

Topographical organization of the brainstem afferents to the lateral posterior-pulvinar thalamic complex in the cat

Following stereotaxic injections of horseradish peroxidase in the dorsal thalamus of the cat which were restricted to the lateralis posterior-pulvinar complex, labelled neurons were found in the superficial layers of the superior colliculus and in the brainstem. The retrogradely-filled cells of the brainstem were situated principally in the nucleus tegmenti pedunculopontinus, the locus coeruleus complex, the parabrachial nuclei and the dorsal tegmental nucleus of Gudden; in each case, labelled cells were more numerous on the ipsilateral side. In addition, some scattered neurons were observed in the central grey matter, the mesencephalic reticular formation, the central superior and dorsal raphe nuclei, the cuneiform nucleus, the nucleus reticularis gigantocellularis, the nucleus praepositus hypoglossi and the oculomotor nuclei. A differential organization of these projections was observed.It is concluded that the rostrointermediate subdivision of the lateralis posterior-pulvinar complex receives most of its connections from the nucleus tegmenti pedunculopontinus, from the deep layers of the superior colliculus and from the other brainstem nuclei, while the caudal subdivision (extrageniculate visual subdivision) receives its main projection from the superficial layers of the superior colliculus. The findings may have functional implications for the role of the complex in oculomotor control.     

A comparative histological study on the uterovaginal junction in the laying hen in embryonated and non-embryonated egg producers

The uterovaginal junction, part of the reproductive duct, was studied in domestic hens, specifically the special tubular structures known as the sperm host gland. The results were compared between two groups—non-embryonated and embryonated egg producers. Relevant samples were collected, processed to paraffin wax blocks, and sections cut and stained with H&E and PAS stains. Two types of glands were observed in the lamina propria and submucosa. The results from the sperm host glands in chicken’s oviduct suggested that it might have a functional role in oviductal sperm storage in and release of spermatozoa from the sperm host glands of native hens. Sperm storage structures in the form of tubules are observed in the wall of the uterovaginal junction. These tubules are lined by both ciliated and secretory cells and may play a role in the storage of sperm. These features showed better development in the group of egg-laying hens producing embryonated eggs in comparison to the ones producing non-embryonated eggs.     

A paleostriatal-thalamic-telencephalic path in pigeons

The efferent connections of the thalamic nucleus dorsointermedius posterior were studied in the pigeon. In pigeons, this thalamic nucleus receives both paleostriatal (basal ganglia) and cerebellar input and has been compared to nuclei of the mammalian thalamic ventral tier on this basis. The present results show that neurons of nucleus dorsointermedius posterior project upon a crescent-shaped neuronal field within the neostriatum intermedium as well as upon the ventral paleostriatum and nucleus intrapeduncularis. The relationship of the neostriatum intermedium field to avian motor pathways is discussed and it is suggested that nucleus dorsointermedius posterior thalami of birds may play a role comparable to that of the mammalian ventral tier nuclei in the neural control of motor functions.The efferent projections of dorsointermedius posterior were contrasted with those of adjacent structures within the avian posterior thalamic complex. Neurons within nucleus dorsomedialis posterior appear to be related to the avian limbic system and project to a neuronal field within the rostromedial portion of the neostriatum intermedium. Neurons in nucleus dorsolateralis posterior have been shown to receive input from the optic tectum;¹² efferents from dorsolateralis posterior were traced to a small triangular wedged-shaped field within the ventromedial portion of the periectostriatal belt.     

The detection of the big liver and spleen agent in infected tissues via intravenous chick embryo inoculation

Partially purified homogenates prepared from the livers of birds affected with BLS were used to inoculate intravenously young adult broiler breeder hens and incubating chicken embryos. Following inoculation, the broiler breeders developed pathological and serological responses typical of BLS infection. The same antigen resulted in persistent antigenaemia in chickens which were inoculated during various stages of incubation. This technique was very sensitive and could be used for detection and titration of virus in tissue preparations. Methods for optimization of the technique were investigated. Chick embryos demonstrated the greatest susceptibility to agent replication when inoculated at 11 days of embryonation. After hatching, agent replication appears to increase with age. Inoculated chickens bled at 8 days of age showed increased incidence of antigenaemia by this procedure.     

Deafferentation-induced caspase-3 activation and DNA fragmentation in chick cochlear nucleus neurons

Cochlea removal severs peripheral processes of cochlear ganglion cells and permanently abolishes afferent input to nucleus magnocellularis (NM) neurons. Deafferented chick NM neurons undergo a series of morphologic and metabolic changes, which ultimately trigger the death of 20%–40% of neurons. Previous studies suggested that this cell specific death involves activation of the intrinsic apoptotic pathway, including increased presence of cytochrome c and active caspase-9 in the cytoplasm of deafferented NM neurons. Interestingly, however, both markers were detected pan-neuronally, in both degenerating and surviving NM neurons [Wilkinson BL, Elam JS, Fadool DA, Hyson RL (2003) Afferent regulation of cytochrome-c and active caspase-9 in the avian cochlear nucleus. Neuroscience 120:1071–1079]. Here, we provide evidence for the increased appearance of late apoptotic indicators and describe novel characteristics of cell death in deafferented auditory neurons. Young broiler chickens were subjected to unilateral cochlea removal, and brainstem sections through NM were reacted for active caspase-3 and terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling (TUNEL). Caspase-3 activation is observed in the cytoplasm of both dying and surviving deafferented NM neurons 24 h to 7 days following cochlea removal, suggesting that caspase-3, usually considered an “executioner” of apoptotic death, may also function as a “modulator” of death. In addition, we find that TUNEL labeling of degraded DNA is observed in deafferented NM. In contrast to upstream apoptotic markers, however, TUNEL labeling is restricted to a subpopulation of deafferented neurons. Twelve hours following cochlea removal, TUNEL labeling is observed as punctate accumulations within nuclei. Twenty-four hours following cochlea removal, TUNEL accumulates diffusely throughout neuronal cytoplasm in those neurons likely to die. This cytoplasmic TUNEL labeling may implicate mitochondrial nucleic acid degradation in the selective death of some deafferented NM neurons. Our study examines the subcellular distributions of two prominent apoptotic mediators, active caspase-3 and TUNEL, relative to known histochemical markers, in deafferented NM; provides new insight into the apoptotic mechanism of cell death; and proposes a role for mitochondrial DNA in deafferentation-induced cell death.     

Decrease in choline acetyltransferase activity in the red nucleus of the cat after cerebellar lesion

The use of a microdissection technique and of a very sensitive radioisotopic assay for choline acetyltransferase, the enzyme that synthesizes acetylcholine, showed that the distribution of this enzyme in the feline red nucleus is uneven. Thus, the enzyme content progressively increased in the caudo-rostral direction, the level at the rostral aspect being about twice that at the caudal. Choline acetyltransferase activity in the cat red nucleus was examined after chronic lesions of the cerebellum. Lesions in the area of the dentate and interpositus nuclei were followed by a decrease in enzyme activity in the contralateral red nucleus, whereas no change was seen on the ipsilateral side. Since this enzyme is a very specific marker for cholinergic neurons, the decrease in enzyme activity caused by the lesions suggests the existence of a cholinergic cerebellorubral pathway. This is supported by the finding that the topographical effects on choline acetyltransferase activity in the red nucleus produced by selective lesions of either the dentate or the interpositus nucleus reflected the arrangement of the cerebellorubral pathways.Choline acetyltransferase activity also decreased in the nucleus ventralis lateralis and the nucleus ventralis anterior of the thalamus contralateral to the lesions. Since cerebello-rubral fibres are thought to be collaterals of cerebello-thalamic axons, at least in the case of these originating in the interpositus nucleus, this would indicate the presence of cholinergic fibres in the brachium conjunctivum (or superior cerebellar peduncle).The results are not in complete agreement with some of the previously reported pharmacological studies; this is discussed.     

The sympathetic postganglionic and sensory innervation of oviducal magnum in hen: a choleratoxin subunit B-conjugated horseradish peroxidase study

The anatomy of the extrinsic innervation of the avian magnum has not been accurately demonstrated previously. In the present study, choleratoxin subunit B-conjugated horseradish peroxidase (CB-HRP) was used as a retrograde tracer to determine the sympathetic postganglionic and sensory innervation of the magnum of hens. With regard to the sympathetic postganglionic innervation, following CB-HRP injections under the serosa of the magnum, CB-HRP-positive neurons were found bilaterally in the C12-LS13 ganglia of the sympathetic chain, splanchnic ganglia and adrenal ganglia. The number of labelled neurons in the left ganglia of the sympathetic chain and splanchnic ganglia was approximately 2.1 times that in the right ganglia. This suggests that the unilateral magnum is bilaterally innervated with sympathetic postganglionic nerves, the left nerves being predominant. With regard to the sensory innervation, following tracer injections, CB-HRP-positive neurons were found bilaterally in the spinal ganglia C13-LS12, jugular ganglia and nodose ganglia. The number of positive cells in the left ganglia was about 2.2 times that in the right ganglia. In the spinal ganglia, 85.6% of the labelled neurons were in the T5-LS2 and LS8-LS11 ganglia. These results suggest that the sensory nerve fibres of the magnum reach the central nervous system principally via two groups of spinal ganglia and vagus nerves, and that the innervation is bilateral although the left-hand route predominates. Moreover, 45.7% of all the CB-HRP-labelled neurons were found in the rectal region of the intestinal nerve of Remak (INR), which suggests that the INR plays a very important role in the functional regulation of the magnum.     

Functions of frontostriatal systems in cognition: comparative neuropsychopharmacological studies in rats, monkeys and humans

A comparative and integrated account is provided of the evidence that implicates frontostriatal systems in neurodegenerative and neuropsychiatric disorders. Specifically, we have made detailed comparisons of performance following basal ganglia disease such as Parkinson's disease, with other informative groups, including Alzheimer's disease, schizophrenia and attention deficit/hyperactivity disorder and structural damage to the frontal lobes themselves. We have reviewed several behavioural paradigms including spatial attention and set-shifting, working memory and decision-making tasks in which optimal performance requires the operation of several cognitive processes that can be successfully dissociated with suitable precision in experimental animals. The role of ascending neurotransmitter systems are analysed from the perspective of different interactions with the prefrontal cortex. In particular, the role of dopamine in attentional control and spatial working memory is surveyed with reference to its deleterious as well as facilitatory effects. Parallels are identified in humans receiving dopaminergic medication, and with monkeys and rats with frontal dopamine manipulations. The effects of serotonergic manipulations are also contrasted with frontal lobe deficits observed in both humans and animals. The main findings are that certain tests of frontal lobe function are very sensitive to several neurocognitive and neuropsychiatric disorders. However, the nature of some of these deficits often differs qualitatively from those produced by frontal lobe lesions, and animal models have been useful in defining various candidate neural systems thus enabling us to translate basic laboratory science to the clinic, as well as in the reverse direction.     

Inhibitory action of a conditioning procedure on visual responsive neurons of the nucleus reticularis thalami in rats

Summary In urethane anesthetized rats neuronal responses of the visual part of nucleus reticularis thalami (vTR) to light were compared with those during pairing light as a conditioned stimulus (CS) with the electrical stimulation of the rat's tail (US). The intensity of the US was adjusted to the minimum required to evoke a slight freezing behavior in the awake rat. The firing rate of most vTR neurons decreased in the period between light and US application (P < 0.01). Significant response modulations to light were observed in 39% of the units, in most of them they persisted over an extinction period of 15 min. In addition, neurons which were predominantly inhibited by conditioning sometimes changed from regular spiking to a burst pattern. The results support the hypothesis that conditioning related facilitation of geniculate neurons observed in previous experiments can be explained at least partly by disinhibition of geniculate units from vTR.