Ida E. Tóth

The neuroendocrinology of the adrenal cortex.

Although until relatively recently assumed to be devoid of innervation, there is now ample proof that the adrenal cortex receives specific neurones of several types. A general interpretation of their roles in the regulation of adrenocortical function has not been forthcoming, probably because of the variety of the different experimental approaches which have been used, and the heterogeneous observations which have been made. We here summarize the evidence which is available, and offer the view that neural inputs may provide fine tuning of the responses to systemic factors such as ACTH, through direct actions on specific adrenocortical cells. However, neural regulation also provides an integrative function, through actions on the flow of blood through the gland, which itself exerts a powerful influence on adrenocortical function.

Neuronal Labeling in the Rat Brain and Spinal Cord from the Ovary Using Viral Transneuronal Tracing Technique

In the present investigations the viral transneuronal labeling method, which is able to reveal hierarchial chains of central nervous system (CNS) neurons, was applied to identify sites in the CNS connected with the ovary and presumably involved in the control of ovarian functions. Pseudorabies virus was injected into the ovaries of rats and a few days later (at various times after the injection) the spinal cord and brain were examined for virus-infected neurons from the ovary. The virus-labeled nerve cells were identified by immunocytochemistry using polyclonal antiviral antibody. Virus-labeled neurons were detected both in the spinal cord and the brain. In the spinal cord such elements were observed in the intermediolateral cell column, in the dorsal horn close to the marginal zone and in the central autonomic nucleus. In the medulla oblongata and pons, neurons of several nuclei and cell groups (area postrema, nucleus of the solitary tract, dorsal vagal complex, nucleus ambiguus, paragigantocellular nucleus, parapyramidal nucleus, A1, A5 and A7 cell groups, caudal raphe nuclei, locus ceruleus, subceruleus nucleus, Barrington’s nucleus, Kölliker-Fuse nucleus) were found to be transneuronally labeled. In the mesencephalon, the ventrolateral part of the periaqueductal gray matter contained virus-labeled neurons. In the diencephalon, a very intensive cell body labeling was observed in the hypothalamic paraventricular nucleus and a few virus-infected neurons could be detected in the lateral and dorsal hypothalamus, in the arcuate nucleus, zona incerta, perifornical area and in the anterior hypothalamus. Concerning the telencephalic structures, virus-labeled cells were found in the bed nucleus of the stria terminalis and in the central amygdala nucleus. These findings provide the first neuromorphological evidence for the existence of a multisynaptic neuronal pathway between the ovary and the CNS, and give a detailed account of the structures involved in this pathway.

Fine structure of sensory nerves in the rat cornea: an experimental nerve degeneration study.

&NA; Fine structure of nerve fibres and terminals in the rat cornea was studied after fixation with glutaraldehyde and osmium tetroxide or with potassium permanganate. Superior cervical and/or ciliary ganglionectomy as well as ophthalmic neurotomy were performed in order to verify the origin of the corneal nerves. In the control corneas axon profiles with granular vesicles were observed in the stroma. Other axons containing agranular vesicles were found both in the stroma and in the epithelium. Superior cervical ganglionectomy abolished only the axons containing granular vesicles but did not affect the corneal blink reflex. Ciliary ganglionectomy induced more conspicuous changes in both stromal and intraepithelial axon profiles. The corneal reflex was, however, normal. Some of the axons containing agranular vesicles also showed degenerative changes. However, intact axon profiles with agranular vesicles were seen even after extirpation of both the ciliary ganglion and the superior cervical ganglion (combined autonomic ganglionectomy). On the other hand, all axon profiles with agranular vesicles disappeared after coagulation of the ophthalmic and maxillary nerves (sensory denervation). This operation destroyed most of the axons in all parts of the cornea and abolished the blink reflex. It is concluded that the axon profiles in the corneal epithelium, containing agranular vesicles, are sensory axons of the trigeminal nerve. A possible role of the vesicles in sensory nerves is discussed.

CNS structures presumably involved in vagal control of ovarian function

The contribution of the vagus nerve to viral transneuronal labeling of brain structures from the ovaries demonstrated recently by us was investigated. Unilateral vagotomy was performed prior to ipsilateral intraovarian virus injection. Virus-infected neurons were visualized by immunostaining. In vagotomized rats such neurons were detected only in certain cell groups of the brain (parapyramidal nucleus, A(1), A(5) cell group, caudal raphe nuclei, hypothalamic paraventricular nucleus, lateral hypothalamus). Vagotomy interfered with labeling of several structures that were labeled in controls, including area postrema, nucleus of the solitary tract, dorsal vagal complex, nucleus ambiguus, A(7) cell group, Barringtons nucleus, locus coeruleus, periaqueductal gray, dorsal hypothalamus. Findings provide a morphological basis to study the functional significance of brain structures presumably involved in the control of ovarian function and acting via the vagus or the sympathetic nerves.

Central Nervous System Structures Labelled from the Testis Using the Transsynaptic Viral Tracing Technique

In the present study, the transneuronal transport of neurotrophic virus technique was used to identify cell groups of the spinal cord and the brain that are transsynaptically connected with the testis. Pseudorabies virus was injected into the testis and after survival times of 3–6 days, the spinal cord and brain were processed immunocytochemically using a polyclonal antibody against the virus. Virus‐infected perikarya were detected in the preganglionic neurones of the spinal cord (T10‐L1, L5–S1) and in certain cell groups and areas of the brain stem, the hypothalamus and the telencephalon. In the brain stem, the cell goups and areas in which labelled neurones were present included, among others, the nucleus of the solitary tract, the caudal raphe nuclei, the locus coeruleus and the periaqueductal grey of the mesencephalon. In the hypothalamus, virus infected perikarya were observed in the paraventricular nucleus and in certain other cell groups. Telencephalic structures containing labelled neurones included the preoptic area, the bed nucleus of the stria terminalis, the central amygdala and the insular cortex. These data identify a multisynaptic circuit of neurones in the spinal cord and in the brain which may be involved in the control of testicular functions.

Lacrimal preganglionic neurons form a subdivision of the superior salivatory nucleus of rat: transneuronal labelling by pseudorabies virus

Transneuronal viral tracing was applied to localize preganglionic parasympathetic neurons in the brainstem which innervate the extraorbital lacrimal gland in the rat. The Bartha strain of pseudorabies virus was injected into the lacrimal gland, and after different survival times, the superior cervical and Gasserian ganglia, the upper thoracic spinal cords and the brainstems were immunostained by antiviral antiserum. Virus-labelled neurons appeared in the ganglia and in the ventrolateral part of the ipsilateral brainstem at the pontomedullary junction 45 h after inoculation. The virus-labelled brainstem neurons comprised a subgroup of the superior salivatory nucleus (SSN) located between the root fibers of the facial nerve and the nuclei of the superior olive, and were clearly distinguished from the tyrosine hydroxylase (TH)-immunopositive, A5 catecholaminergic neurons by double immunostaining. The number of infected cells in the ipsilateral SSN was increased by 72 h, and labelled neurons appeared in the intermediolateral cell column (IML) of the ipsilateral thoracic spinal cord. In rats with cervical ganglionectomy prior to the virus injection in the lacrimal gland, virus-infected cells appeared in the SSN, but not in the thoracic spinal cord, indicating that preganglionic SSN cells were infected via parasympathetic axons of the facial nerve. A double-virus tracer labelling technique was applied to determine the topographical relationship between the preganglionic parasympathetic neurons of the lacrimal gland and those of the submandibular gland within the SSN. Simultaneous injection of Bartha strain of pseudorabies virus into the submandibular gland, and a lacZ gene-containing Bartha-derived virus strain into the lacrimal gland (and vice versa) demarcated a ventral lacrimal and a dorsal submandibular subgroup in the SSN.

Neuropeptides in the adrenal gland: Distribution, localization of receptors, and effects on steroid hormone synthesis

In this review we defined and classified the neuropeptides (NPs) related to the adrenal gland, according to Palkovits (Frontiers Neuroendocrinol 10:1 1988). The concentration (RIA) and distribution (immunohistochemistry) of NPs, as well as the localization of the receptors (radioligand studies) were summarized. Direct effects of NPs on aldosterone and corticosterone synthesis obtained by in vivo, in situ perfusion, and in vitro experimental approaches were reviewed. Data (from different rat strains and genders) for 35 NPs are presented.

Identification of CNS neurons involved in the innervation of the epididymis: A viral transneuronal tracing study

Cell groups of the spinal cord and the brain transsynaptically connected with the epididymis (caput, cauda) were identified by means of the viral transneuronal tracing technique. Pseudorabies virus was injected into the caput or the cauda epididymidis, and after survival times 4 and 5 days, the spinal cord and brain were processed immunocytochemically. Virus-labeled neurons could be detected in the preganglionic sympathetic neurons (lower thoracic and upper lumbar segments) and following virus injection into the cauda epididymidis, also in the sacral parasympathetic nucleus (L6-S1). Virus-infected perikarya were present in several brain stem nuclei (lateral reticular nucleus, gigantocellular and paragigantocellular nucleus, A5 noradrenergic cell group, caudal raphe nuclei, locus coeruleus, Barringtons nucleus, nucleus of the solitary tract, periaqueductal gray) and in the diencephalon (hypothalamic paraventricular nucleus, lateral hypothalamus). At the longer survival time, some telencephalic structures also exhibited virus-labeled neurons. The distribution of infected neurons in the brain was similar after virus injection into the caput or cauda epididymidis; however, earlier onset of infection was observed after inoculation into the cauda. The present findings provide the first morphological data on a multisynaptic circuit of neurons innervating the epididymis and presumably involved in the control of epididymal functions. reserved.

Recent findings on the organization of central nervous system structures involved in the innervation of endocrine glands and other organs; observations obtained by the transneuronal viral double-labeling technique.

This review summarizes the data obtained with the aid of the recently introduced dual viral tracing technique, which uses isogenic recombinants of pseudorabies virus that express unique reporter gene. This approach made possible to explore simultaneously neural circuits of two organs. The results of these studies indicate: (1) there are neurons innervating exclusively a given organ; (2) left-sided predominance in the supraspinal innervation of the endocrine glands (adrenal, ovary) studied, so far; (3) viral co-infection of neurons, i.e., special neuronal populations coexist in different brain areas that are transsynaptically connected with both paired endocrine and non-endocrine organs, endocrine glands and non-endocrine organs, and organs of bodily systems other than the endocrine one. The number of common neurons seems to be related to the need of coordinating action of different systems. The data on co-infection of neurons suggest that the central nervous system has the capacity to coordinate different organ functions via common brain neurons providing supraspinal innervation of the organs.

Transneuronal labelling of nerve cells in the CNS of female rat from the mammary gland by viral tracing technique

Using the viral transneuronal tracing technique, the cell groups in the CNS transneuronally connected with the female mammary gland were detected. Lactating and non-lactating female rats were infected with pseudorabies virus injected into the mammary gland. The other group of animals was subjected to virus injection into the skin of the back. Four days after virus injection, infected neurons detected by immunocytochemistry, were present in the dorsal root ganglia ipsilateral to inoculation and in the intermediolateral cell column of the spinal cord. In addition, a few labelled cells could be detected in the dorsal horn and in the central autonomic nucleus (lamina X) of the spinal cord. At this survival time several brain stem nuclei including the A5 noradrenergic cell group, the caudal raphe nuclei (raphe obscurus, raphe pallidus, raphe magnus), the A1/C1 noradrenergic and adrenergic cell group, the nucleus of the solitary tract, the area postrema, the gigantocellular reticular nucleus, and the locus coeruleus contained virus-infected neurons. In some animals, additional cell groups, among others the periaqueductal gray and the red nucleus displayed labelling. In the diencephalon, a significant number of virus-infected neurons could be detected in the hypothalamic paraventricular nucleus. In most cases, virus-labelled neurons were present also in the lateral hypothalamus, in the retrochiasmatic area, and in the anterior hypothalamus. In the telencephalon, in some animals a few virus-infected neurons could be found in the preoptic area, in the bed nucleus of the stria terminalis, in the central amygdala, and in the somatosensory cortex. At the longer (5 days) survival time each cell group mentioned displayed immunopositive neurons, and the number of infected cells increased. The pattern of labelling was similar in animals subjected to virus inoculation into the mammary gland and into the skin. The distribution and density of labelling was similar in lactating and non-lactating rats. The present findings provide the first morphological data on the localization of CNS structures connected with the preganglionic neurons of the sympathetic motor system innervating the mammary gland. It may be assumed that the structures found virus-infected belong to the neuronal circuitry involved in the control of the sympathetic motor innervation of the mammary gland.