Reaction of neurons of the basolateral group of nuclei of the amygdaloid complex to gonadectomy in the rat

By means of the karyometry method 26 zones in the basolateral group of the amygdaloid complex (AC) nuclei in rats have been studied 1 month after castration. All the main parameters characterizing distribution of the neuronal nuclei volume logs in the zones studied have been calculated. In males two regions have been revealed, in which certain reaction of the cellular neuronal nuclei to the experimentally produced deficit of sex hormones in the organism is felt. One of them is situated in the AC anterior part and includes all the nuclei of the basolateral group, the second is situated in the posterior part, occupies a rather vast area and is formed at the expense of all the nuclei of the basolateral group and adjoining structures (the dorsal endopiriform nucleus and piriform cortex). In females there is one region responding to gonadectomy, which is mainly formed at the expense of central and posterior parts of the basolateral nucleus. Basing on the lack of the structural-functional uniqueness revealed in different parts of the cortico-medial and basolateral groups of the AC nuclei, it is suggested to distinguish anterior, central and posterior parts in their composition.     

Cytologic characteristics of "dark" and "light" cells in the brain amygdaloid complex

This paper reports data on cytological peculiarities of neurons of two main zones of sexual dimorphism in brain amygdala (dorsomedial nucleus and anterior cortical nucleus). The main attention was paid to some characteristics of "dark" and "pale" cells found in the amygdaloid complex for the first time. It is supposed that the dark and pale cells are targets for gonadal steroids, whose cyclic changes in concentration in the blood difined their functional states. Though the ultrastructure of dark and pale cells of the amygdaloid complex is similar to that of neurosecretory cells of hypothalamus, there are necessary electron microscopic and cytochemical evidences.     

The role of various parts of the amygdaloid complex in the regulation of activity of respiratory neurons]

In microelectrophysiological investigations influences of different nuclear regions of the amygdaloid complex on the spike activity of the functionally identified single respiratory neurons of the medulla oblongata were studied in anesthetized cats. It was established a qualitative different character of the changes of unit activity of the medullary respiratory neurons in case of stimulation of phylogenetically old corticomedial or new basolateral nuclear groups of the amygdala. It was shown higher reactivity of the investigated neurons to stimulation of the corticomedial nuclei than basolateral. The influences of the corticomedial nuclear groups on the bulbar inspiratory and expiratory neurons were facilitatory as well as inhibitory with prevailing excitatory effects. It was found that influences of the phylogenetically new neoamygdaloid structures of basolateral region on spike activity of the bulbar respiratory neurons differ accordingly to their topographical differentiation. Mechanisms of amygdaloid control of activity of the medullary respiratory neurons are discussed.     

Zones of sexual dimorphism in the cortico-medial group of nuclei of the amygdaloid complex

With the aim to reveal sex demorphic zones by means of caryometry, 22 zones of the cortico-medial group of the amygdaloid complex (AC) nuclei have been investigated in rats (15 males and 10 females). Per each zone investigated 200 cellular nuclei are measured. Parameters characterizing distribution of the neuronal nuclei volumes in the zones studied are calculated, influence of the sex factor on the nuclear size are revealed by means of variance analysis. Basing on the results of the investigation, a complete idea on topography of the sex demorphic zones in the territory of the cortico-medial group of the AC nuclei is given. These zones are predominantly localized in the anterior and posterior parts of the AC, situating mainly in the rostral and caudal areas of the medial and cortical nuclei. The results demonstrate existence of the rostro-caudal gradient in the structural-functional organization of the cortico-medial group of the AC nuclei and prove that before suggested division of the AC into anterior, central and posterior parts is correct. It is possible to suppose that the cause of accumulated and still accumulating in the literature contradictions on functional differentiation of the AC is lack of registration of sex differences and of the rostro-caudal gradient in organization of this cerebral formation.     

Analysis of the effects of electrical stimulation of certain limbic structures

It has been established that stimulation of the structures of the limbic system (hippocampus, amygdaloid complex, septum) and the medial nucleic of the thalamus of rabbits in conditions of free behavior elicits four basic types of behavioral reactions: arousal, orientation-investigatory, aggressive-defensive and various epileptiform (convulsive) reactions. Activation of behavior, i.e., arousal and the orientation-investigatory reaction, constantly appear on stimulation of the unspecific thalamic nuclei. The aggressive-defense reaction is elicited by stimulating the nuclei of the amygdaloid complex of the ventral part of the hippocampus and the ventromedial nuclei of the thalamus. The epileptiform reactions are most readily reproduced on stimulation of the amygdaloid complex and the ventral part of the hippocampus. The threshold for the appearance of discharges of the aftereffect is very low. The latter are more sustained on stimulation of the basolateral part of the amygdala and the ventral part of the hippocampus. In rabbits as compared with higher animals the discharges on stimulation rapidly spread not only to the limbic system but also to the reticular formation and the neocortex.Kharkov Medical Institute. Translated from Neirofiziologiya, Vol. 1, No. 2, pp. 194–201, September–October, 1969.     

A comparative volumetric analysis of the amygdaloid complex and basolateral division in the human and ape brain

The amygdaloid complex functions to facilitate effective appraisal of the social environment and is an essential component of the neural systems subserving social behavior. Despite its critical role in mediating social interaction, the amygdaloid complex has not attracted the same attention as the isocortex in most evolutionary analyses. We performed a comparative analysis of the amygdaloid complex in the hominoids to address the lack of comparative information available for this structure in the hominoid brain. We demarcated the amygdaloid complex and the three nuclei constituting its basolateral division, the lateral, basal, and accessory basal nuclei, in 12 histological series representing all six hominoid species. The volumes obtained for these areas were subjected to allometric analyses to determine whether any species deviated from expected values based on the other hominoids. Differences between groups were addressed using nonparametric comparisons of means. The human lateral nucleus was larger than predicted for an ape of human brain size and occupied the majority of the basolateral division, whereas the basal nucleus was the largest of the basolateral nuclei in all ape species. In orangutans the amygdala and basolateral division were smaller than in the African apes. While the gorilla had a smaller than predicted lateral nucleus, its basal and accessory basal nuclei were larger than predicted. These differences may reflect volumetric changes occurring in interconnected cortical areas, specifically the temporal lobe and orbitofrontal cortex, which also subserve social behavior and cognition, suggesting that this system may be acted upon in hominoid and hominid evolution.     

Structural-functional organization of the brain amygdaloid complex in the dynamics of the estrous cycle

As a result of amygdaloid complex detailed histology-physiological investigation statistically proved increase in estrus has been discovered in comparison with metestrus of medium size cell nucleus of some cortico-medial group structures and basolateral nucleus. The presence of differences in the level of estrogen binding of rostral and caudal parts of this brain structure, taking place both in male and female rats has been shown for the first time. It was also discovered the dependence of the level of estrogen binding on estrus stage.     

The effect of stimulation of the amygdala basolateral nuclei on the neuron activity of Deiters vestibular nuclei in rabbits

A modulating character of the amygdala basolateral nuclei effect upon the vestibular sensory system was determined in rabbits [correction of rats]. A mechanism of the descending effect of the amygdaloid complex on the activity of the Deiters nucleus neurons, is discussed.     

人胎杏仁核基底外侧核群含一氧化氮合酶神经元的发育

用组织化学方法研究了人胎杏仁核基底外侧核群含一氧化氮合酶（ＮＯＳ）神经元的发育。胎龄分别为１６,２１,２３,２８,３１,３８周。ＮＯＳ阳性神经元在基底外侧核群存在有两种不同的发育模式。１．在外侧核和基底核,单位面积内的阳性细胞数分别在２１周,２３周时较多,随后渐减,从３１～３８周又开始增多。２．在付基底核,２１周时阳性细胞数较多,２３周时减少,随后渐增多。从３１～３８周又渐减少。ＮＯＳ阳性神经元在整个基底外侧核群内的均面积的变化,从１６～２８周ＮＯＳ阳性神经元的均面积是渐增大的,从２８～３１周有所减少。从３１～３８周又渐增大。结果提示,ＮＯＳ阳性神经元出现于人胎基底外侧核群的发育早期,在此核的发育过程中起着很重要的作用     

Cytological characteristics of the anterior amygdaloid area neurons and their reactive changes on a background of various levels of gonadal steroids

The work deals with cytological characteristics of neurons, glias and synapses of the anterior amygdaloid area of rat brain amygdaloid complex, one of the areas of sexual dimorphism, at the stage of estrous and after gonadectomy. The electron microscopic investigation of neurons at the stage of estrous has revealed that greater part of neurons display increased or moderate activities. A decrease in the functional activities of AAA neurons was observed after gonadectomy.     

Effect of the bilateral amygdaloid complex lesion on the hypothalamic l-leucinaminepeptidase activity in the male adult (author's transl)

The effect of bilateral lesion of the amygdaloid nuclear complex on the hypothalamic L-leucinaminepeptidase (LAP) activity has been studied in the rat. Amygdalectomized animals show an increase in this activity, specially when lesion extends to the whole complex or when the basolateral and basomedial nuclei remain intact. The increase in LAP activity is not so significant when the lesion does not affect the cortical nucleus.     

Quantitative comparison of the amygdala in insectivores and primates.

Comparative architectonic studies have resulted in a classification of the amygdaloid complex which differs somewhat from the commonly used classification (first proposed by Humphrey, 1936) by separating the cortical amygdaloid nucleus from the centromedial group and assigning it to the basolateral group, which then forms a cortico-basolateral group. The size changes of these groups and of the nucleus of the lateral olfactory tract (belonging to the centromedial group) and the large-celled part of the basal nucleus (belonging to the corticobasolateral group) have been investigated in representatives of an ascending primate scale. In all structural complexes investigated so far, the small-celled part of the cortico-basolateral group is the most progressive. In descending order of progression there follow: the corticobasolateral group as a whole, the amygdala as a whole, and the large-celled basal nucleus. No clear changes were found in the centromedial group as a whole, whereas the size of the nucleus of the lateral olfactory tract, which represents a small component of this latter group, shows a strong reduction. These differences in the developmental trends point to increasing or decreasing capacities of the functional (limbic and olfactory) systems, to which these structures are related.     

Comparison of Dopamine Uptake in the Basolateral Amygdaloid Nucleus, Caudate-Putamen, and Nucleus Accumbens of the Rat

Abstract: Regional differences in the kinetics and pharmacological inhibition of dopamine uptake were investigated with fast-scan cyclic voltammetry in both the intact rat brain and a brain slice preparation. The regions compared were the basolateral amygdaloid nucleus, caudate-putamen, and nucleus accumbens. The frequency dependence of dopamine efflux evoked in vivo by electrical stimulation of the medial forebrain bundle was evaluated by nonlinear curve fitting with a Michaelis-Menten-based kinetic model. The K _m for dopamine uptake was found to be significantly higher in the basolateral amygdala (0.6 µ M ) than in the other two regions (0.2 µ M ), whereas the V _max value for dopamine uptake in the basolateral amygdala was significantly lower (0.49 µ M /s vs. 3.8 and 2.4 µ M /s in the caudate and accumbens, respectively). Similar kinetics were also obtained in brain slices. Addition of a dopamine uptake inhibitor, cocaine or nomifensine (10 µ M ), to the perfusion buffer increased the apparent K _m value >25-fold in slices of both the caudate-putamen and nucleus accumbens. In contrast, neither uptake inhibitor had an observable effect in the basolateral amygdaloid nucleus. Thus, dopamine uptake in the rat brain is regionally distinct with regard to rate, affinity, and sensitivity to competitive inhibition.     

Neuronal activity in the amygdaloid structure during the sleep-wake cycle of the rat

The pattern of neuronal spike activity in the amygdaloid structure was studied in the sleep-wake cycle during experiments on unrestrained rats. It was shown that most neurons of the dorsomedial portion of the amygdala display greater spike activity during active wakefulness (80%) and paradoxical sleep (66.7%) than during slow-wave sleep. Most neurons of the basolateral amygdaloid region discharged at high frequency during active wakefulness (84.6%) and during paradoxial sleep (38.4%) compared with the frequency of firing during slow-wave sleep. Some neurons were found whose rate of discharge rose during slow-wave sleep in comparison with a similar period of paradoxical sleep (38.4%) and of active wakefulness (7.7%). Our findings show how the pattern of neuronal activity in the dosromedial and basolateral regions of the amygdaloid structure differs at various stages of the sleep-wake cycle. It is postulated that this structure serves mainly to regulate emotionally motivated processes rather than helping to govern the basic mechanisms of the sleep-wake cycle.Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 17, No. 6, pp. 747–756, November–December, 1985.     

Neuronal organization of the periamygdaloid cortex in the cat brain

Neuronal organization of the fields Pmm, Pml2, Pe and epm of the periamygdaloid cortex of the cat brain has been studied by means of Golgi and Nissl methods. The field Pmm essentially differs from other fields of this cortex by primitiveness of its cytoarchitectonic an neuronal organization (two layers uniform by the composition of their neurons are distinguished, the structure of the latter is relatively primitive). In the medial part of this field long axonal rarely branching short dendritic, and in the lateral part--poorly differentiating pyramidal and spindle-like cells predominate. The field Pmm can be considered as a transitional formation between the subcortex (the medial nucleus of the amygdaloid body) and other fields of the periamygdaloid cortex. The fields Pml2, Pe and epm are built more complexly: the cells are organized in 4 layers, more complexly differentiated by their form and size than in the field Pmm and correspondingly more various (long axonal densely branching cells are observed: pyramidal and spindle-like--of the cortical type and bushy--of the subcortical type, as well as long axonal rarely branching reticular cells). The short axonal cells in the fields Pml2, Pe and epm are rather variable in their form, size and direction of axons; in the field Pmm they are less numerous. The field Pmm and the complex of the fields Pml2, Pe and epm are perhaps different in their function, this is evident from different projection of their neurons. Axons of the cells in the field Pmm get into less differentiated and the most ancient medial nucleus of the amygdaloid body and into the ancient system of connections of the latter--terminal strip, and neurons of the fields Pml2, Pe and epm are projected into the basolateral part of the amygdaloid body and into the external capsule--phylogenetically younger structures. Besides, poverty of the axonal collateralies in the long axonal neurons and a small amount and uniformity of the forms of the short axonal cells in the field Pmm and contrary, rich collateralies and variety of short axonal cells in the composition of other fields demonstrate more complex internal integrative function, performing in that composition.     

Sexual dimorphism in the long term speech spectrum

Long-term speech sound spectra of 82 female and 58 male students were computed digitally. Sexual dimorphism of the spectra became apparent by 3 statistical methods: multidimensional scaling of overall similarity data, analysis of variance and discriminant analysis. The spectral amplitude distribution between 80 and 300 Hz showed the highest dimorphism, due to differences in the mean fundamental frequency caused by the larynx. Also frequency regions above 1 kHz contain marked dimorphism leading to an automatic sex recognition rate of 87%. This second dimorphism is mainly caused by the vocal tract resonance. A hypothesis is presented in which these two independent dimorphic structures are compared with consideration to their phylogenetic age.     

Effects of PKA modulation on the expression of neuropeptide Y in rat amygdaloid structures during ethanol withdrawal

We recently reported that neuropeptide Y (NPY) protein levels and cAMP responsive element binding (CREB) protein phosphorylation are lower in amygdaloid structures during ethanol withdrawal after chronic exposure. Furthermore, we reported that normalization of CREB phosphorylation by infusing protein kinase A (PKA) activator into the central amygdala prevents anxiety-like effects in rats during ethanol withdrawal. Here we investigated whether normalization of CREB phosphorylation by infusing PKA activator (Sp-cAMP) into the central amygdala also normalizes the expression of NPY during ethanol withdrawal. Sprague-Dawley male rats were cannulated targeting the central amygdala and then treated either with Lieber-DeCarli ethanol diet or control diet for 15 days. Subsequently ethanol-fed rats were withdrawn for 0 and 24h. The control-diet fed and ethanol-withdrawn rats were infused twice with PKA activator or inhibitor (Rp-cAMP). The protein and mRNA levels of NPY were determined in amygdaloid structures using gold-immunolabeling and the in situ RT-PCR procedure. It was found that chronic ethanol treatment has no effect on mRNA and protein levels of NPY in the central, medial, or basolateral amygdala. On the other hand, ethanol withdrawal produced significant reductions in mRNA and protein levels of NPY in the central and medial but not in the basolateral amygdala. The reductions in mRNA and protein levels of NPY were normalized in the central amygdala by infusion with PKA activator in ethanol-withdrawn rats. On the other hand, PKA-inhibitor infusion does not have any effect on mRNA and protein levels of NPY in the central amygdala of ethanol-withdrawn rats, but significantly decreased the expression of NPY in the central amygdala of control-diet fed rats. These results suggest that the decreased cellular expression of NPY in the central amygdala may play an important role in the CREB-mediated regulation of anxiety-like behaviors during ethanol withdrawal.     

Scent-marking in the tamarin, Saguinus oedipus: Sex differences and ontogeny

Many mammalian species which exhibit scent-marking behaviour show a pronounced sexual dimorphism in marking behaviour and scent gland morphology. However, several species of marmosets and tamarins do not show dimorphism in these traits. We examined sex differences in scent-marking structures and behaviour in cotton-top tamarins (Saguinus o. oedipus; Primates: Callitrichidae). While body size and weight were virtually identical in adult males and females, there were pronounced sex differences in scent gland size and in rates of marking behaviour. Females possessed larger anogenital and suprapubic glands and showed 10-fold higher rates of anogenital marking and slightly higher rates of suprapubic marking than males. Observations on the development of anogenital marking revealed a lack of dimorphism during the first 2 years. Adult rates of anogenital marking in females were only observed in females housed separately from their natal family group. The onset of adult levels of marking behaviour corresponds with the adoption of the role of a breeding adult female, suggesting that anogenital marking plays a role in sexual communication.     

Sex differences in the growth of the human bony pelvis

The study of individual patterns of longitudinal growth of the bony pelvic complex reveals the following findings concerning the sex differences in the growth of the bony pelvis. (1) The patterns of growth show the same individual variability and male-female overlap as the adult configuration of pelves. (2) The sex differences in the adult bony pelvis cannot be attributed to the differential response of one bone to sex hormone. (3) Sex differences develop from complicated variations in rates and direction of growth of local areas of the pelvic complex. (4) The superior functional division of the bony pelvis shows only one notable sex difference — the sexual dimorphism of the directional growth of the anterior one-half of the iliac crest. (5) The inferior functional division of the bony pelvis shows numerous local areas of sexually dimorphic growth, but the major sex differences result from the greater lateral migration of the ischia. (6) Of the regions showing definite sexual dimorphism in growth, the pelvic inlet and sciatic notch are the more variable because of their dependency on two separate anatomical systems for their final adult morphological configuration. The subpubic angle and length of the superior pubic ramus are directly associated with only one anatomical system, the enlargement of the pelvic cavity, thus, they show less variability and more definitive sex difference.