Biomedical subjects

K J Berkley

Publications and source records attributed to K J Berkley.

At least 19 recordsLinked to original sources

PubMed1992

Estrous cycle variation of afferent fibers supplying reproductive organs in the female rat.

Multi-unit afferent nerve activity was recorded from branches of the hypogastric and pelvic nerves in virgin female rats on different days of the estrous cycle. In each rat, the response of hypogastric nerve fibers to uterine distension and the response of pelvic nerve fibers to vaginal distension was tested. The minimal pressure necessary to evoke a response was highest in diestrus for both the hypogastric and pelvic nerve fibers. For the hypogastric nerve, the minimal necessary pressures were significantly lower during both proestrus and estrus, whereas for the pelvic nerve, the pressure was significantly lower only on the day of proestrus. These results suggest that the overall response sensitivity of afferent fibers in the pelvic and hypogastric nerves are differentially affected by hormonal variations occurring across the estrous cycle in a manner that would enhance reproduction.

Afferent Pathways↗

PubMed1992

A re-examination of the spino-reticulo-diencephalic pathway in the cat.

One commonly accepted idea is that affective aspects of pain sensation are derived from a flow of information from the spinal cord through the reticular formation to the intralaminar thalamus and subthalamus. Little is known, however, about the extent to which spinoreticular terminations and reticulodiencephalic neuronal cell bodies overlap. This study used a combination of anterograde and retrograde tracing techniques to compare these distributions in the cat. Whereas spinoreticular terminations were concentrated caudally and laterally, neurons projecting to intralaminar thalamus and subthalamus were concentrated rostrally and medially. Thus, information conveyed from the spinal cord to the reticular formation appears to have direct access to intralaminar thalamus and subthalamus only by way of a few widely scattered neurons. When considered with the results of others, these results encourage less emphasis on a putative spino-reticulo-diencephalic pathway for pain. Rather, the reticular formation's role in pain is more likely to involve its full complement of interconnected descending and ascending connections.

Animals↗

PubMed1992

Vive la différence!

Hormonal effects are increasingly recognized as important influences on neuronal function and, ultimately, on animal behavior. Such 'higher' behavioral effects are well studied, particularly in relation to sexually dimorphic behaviors. Yet, somewhat surprisingly, a significant proportion of more basic neuroscience research papers fail to specify the sex of the subjects used. In this brief article Karen Berkley argues that knowledge of, and controlling for, the sex of research animals is important. In addition, if females are used, their reproductive-cycle status could provide a deliberate strategy to investigate the effects of gonadal steroid hormones on biological functions.

Animals↗

PubMed1992

Glial cells: possible determinants of neuronal uptake of tritiated proline.

When tritiated proline is injected into various sensory and integrative areas of the brain, it fails to be incorporated into the proteins of neuronal soma located within the injection site. In contrast, such incorporation does occur when [3H]proline is injected into dorsal root ganglia. The basis for this difference is unclear because brain and dorsal root ganglion tissue differ in configurational factors (e.g. synapses, dendrites) as well as in the embryological origin of their respective neuronal and non-neuronal cell populations. To determine if configurational factors might account for [3H]proline's incorporation into somal neuronal proteins in dorsal root ganglia, [3H]proline was injected into autonomic (pelvic and superior cervical) and sensory (dorsal root and nodose) ganglia in the rat. These ganglia differ in synaptic and cellular configurations, but have the same neural origin (neural crest). Virtually all neuronal soma were labeled in autoradiograms of all of these injection sites, suggesting that configurational factors do not account for the labeling of dorsal root ganglion neurons by [3H]proline. To address the issue of embryological origin, cellular labeling patterns after [3H]proline injection into the hypoglossal nucleus, dorsal motor nucleus of the vagus and the ventral horn of spinal cord were compared with those after [3H]proline injections into the adjacent solitary nucleus, gracile nucleus and central cervical nucleus of the spinal cord. The neurons in the former three nuclei (i.e. motoneurons) originate from the neural tube, but their axons are associated primarily with Schwann cells which originate from the neural crest. Although neurons in the latter three regions also originate from the neural tube, their axons are myelinated entirely by neural tube-derived glia (i.e. oligodendrocytes).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Effects of colchicine on retrogradely-transported WGA-HRP.

The effects of colchicine treatment on retrogradely-transported WGA-HRP were examined in the cat. The ventroposterolateral nucleus of the thalamus was bilaterally injected with WGA-HRP followed 2 days later by a unilateral injection of colchicine into the dorsal column nuclei (DCN). The cats were sacrificed by perfusion 24 h later. Retrogradely-transported WGA-HRP within DCN neurons was visualized in coronal, vibratome-cut sections of the medulla using the procedure of Rye and collaborators (J. Histochem. Cytochem., 32 (1984) 1145-1153). On the uninjected side, as expected, the reaction product filled numerous neuronal perikarya and their dendrites. In contrast, on the colchicine-treated side, the reaction product was restricted to dendrites; little labeling was observed within perikarya. These findings appear to reflect colchicine's effects on the translocation of lysosomes from neuronal perikarya to their dendrites are important for the interpretation of data from experiments using colchicine to enhance perikaryal immunohistochemical staining.

Animals↗

PubMed1991

Cerebellar projections to the somatic pretectum in the cat.

Neurons in the somatic pretectum receive input from the dorsal column nuclei (DCN) and project to a comparable "somatic" portion of the dorsal accessory nucleus of the inferior olive (DAO). This somatic DAO is reciprocally connected with the anterior interpositus nucleus of the cerebellum. One question that arises is whether this circuitry is further controlled by an output specifically from the anterior interpositus nucleus to the somatic pretectum. Wheatgerm agglutinin conjugated to horseradish peroxidase was injected into various parts of the cat pretectum. Injection sites were interpreted as including the somatic pretectum if neurons in the DCN were retrogradely labeled and if anterograde terminal labeling occurred in somatic DAO. The locations of retrogradely labeled neurons within the deep cerebellar nuclei were then compared in cases in which the injection sites included or excluded the somatic pretectum. In all cases in which the injection site included the somatic pretectum, retrogradely labeled neurons were observed in the anterior interpositus nucleus as well as in the lateral cerebellar nuclei. In some of these cases, neurons in the posterior interpositus and medial nuclei were also labeled. In contrast, in cases in which the pretectal injection site was located outside or at the border of the somatic pretectum, retrogradely labeled neurons were observed only in the lateral, posterior interpositus, and medial nuclei. Thus, the somatic pretectum appears to receive input primarily from neurons in the anterior interpositus nucleus, along with some input from neurons in the lateral nucleus. These results provide additional evidence for a pathway through the DCN in which sequentially processed somatic information has access to and is modulated by cerebellar circuitry. The existence of such a pathway supports the conclusion that neurons in the DCN convey somatic information important not only for cutaneous, kinesthestic, and other bodily sensations, but also for the control of movement.

Afferent Pathways↗

PubMed1990

Relays from the spinal cord and solitary nucleus through the parabrachial nucleus to the forebrain in the cat.

Projections from the spinal cord and solitary nucleus to the lateral parabrachial nucleus (PBN1) in the cat were directly compared using double anterograde tracing methods. The two inputs were found to overlap within a well-circumscribed zone in the rostral 2/3 of PBN1. This zone was flanked ventrally by a zone receiving only solitary nucleus input and dorsally by a zone receiving only spinal input. Other authors have shown that neurons within these three recipient zones (overlap area, solitary nucleus and spinal cord) project to different forebrain targets (hypothalamus, amygdala and thalamus, respectively). This orderly input-output organization is likely to provide part of the framework for PBN's complex involvement in the coordination of respiratory and cardiovascular activities and their association with pain, visceral sensation and emotion.

Afferent Pathways↗

PubMed1990

Convergent inputs to the inferior olive from the dorsal column nuclei and pretectum in the cat.

The dorsal column nuclei (DCN) consist of an anatomically heterogeneous population of neurons, some of which project to the inferior olive and pretectum. Recent anatomical experiments on cats have shown that neurons in the parts of the pretectum which receive input from DCN also project to the inferior olive. Thus, DCN neurons provide an input to the inferior olive via both a direct DCN-olivary pathway and an indirect pathway through the pretectum. This connective situation provides a mechanism by which incoming somatic sensory information that is processed at different levels of the brainstem (i.e. DCN and pretectum) has access to the cerebellum by way of the inferior olive. It is of interest whether the two sets of differently processed information are conveyed to the same group of inferior olive neurons. Although DCN and pretectal projections to the inferior olive have been generally described, the relationship between the DCN targets in the inferior olive and those specifically from the DCN-recipient parts of the pretectum have not. To address this question, this study used single and double anterograde labeling strategies with a variety of tracers to compare the two targets in the inferior olive of cats. It was found that projections to the inferior olive from the DCN-recipient parts of the pretectum were located predominantly in the dorsal accessory portion of the inferior olive where they overlapped extensively with projections directly from DCN. These results provide evidence for a pathway by which sequentially processed somatic sensory information, first in the DCN and then in the pretectum, has access to the cerebellum by way of the same group of inferior olive neurons.

Animals↗

PubMed1990

Responses of hypogastric nerve afferent fibers to uterine distension in estrous or metestrous rats.

The response of afferent fibers in the distal end of the cut hypogastric nerve to distension of the uterus to various pressure levels was investigated in anesthetized virgin female rats on two different days of the estrous cycle (estrus or metestrus). Whereas relatively intense levels of uterine distension produced an increase in afferent activity in a pressure-dependent manner in both stages of the estrous cycle, the minimal pressure necessary to activate the fibers was significantly less on the day of estrus. These results suggest that hypogastric nerve afferent fibers are more likely to respond to potentially damaging uterine stimuli during the time when such responsiveness would be most important for reproductive success.

Action Potentials↗

PubMed1990

Functional properties of afferent fibers supplying reproductive and other pelvic organs in pelvic nerve of female rat.

1. Electrophysiological techniques were used to characterize responses of afferent fibers in pelvic nerve of adult, virgin female rats to mechanical or chemical stimulation of internal reproductive organs and to mechanical stimulation of other pelvic organs. 2. In an in vivo barbiturate-anesthetized preparation, pelvic nerve afferent fibers responded to a wide variety of mechanical stimulation applied to restricted regions of the vaginal canal, caudal uterus (body and cervix), bladder, ureter, colon, or anus. 3. Single-fiber mechanoreceptive fields were invariably confined to a single organ. Notably, responses could be evoked not only by gentle stimulation of the unit's receptive field directly on the organ itself, but also by stimulating the field indirectly with intense stimulation through the appropriate part of a contiguous organ. This innervation feature is consistent with the separability of pelvic organ functions under innocuous conditions but their confusion under noxious ones. 4. Receptive fields on the reproductive organs extended from the caudal edge of the vagina to the uterine body (including the cervix) but were most often located in the fornix (vaginocervical junction). Most units had no or low levels of spontaneous activity. Their responses to mechanical stimuli were usually slowly or moderately adapting and time-locked to the stimulus. 5. Fibers with vaginal receptive fields (including the fornix) responded best either to vaginal distension with a balloon or, more often, to a probe moving along the internal vaginal surface in a direction toward the cervix. They were observed most frequently during the proestrus stage of the rat's estrous cycle. These fibers, therefore, seem particularly suited for relaying information about stimuli that occur during mating. 6. Fibers with receptive fields on the uterine cervix and body responded best to static pressure and were observed less frequently than those with vaginal fields, regardless of estrous stage. They were, however, sensitized by hypoxia. In addition, irritation of the uterus increased the probability of observing them. These fibers, therefore, may exert their primary function during reproductive conditions different from those of virgin rats, such as parturition. 7. Response activity of most of the mechanoreceptive afferent fibers supplying reproductive organs increased as the stimulus intensity increased into the noxious range; i.e., into a range in which the stimulus momentarily produced ischemia at the stimulus site. In addition, in an in vitro preparation, pelvic nerve fibers responded in a dose-dependent manner to injections through the uterine artery of bradykinin (BRAD) as well as to other algesic chemicals, 5-hydroxytryptamine (5-HT) and KCl.(ABSTRACT TRUNCATED AT 400 WORDS)

Adnexa Uteri↗

PubMed1989

Spinal input to the parabrachial nucleus in the cat.

The projections from the spinal cord to the parabrachial nucleus in the cat were investigated using both the degeneration method and the anterograde transport of wheat germ agglutinin-horseradish peroxidase conjugate. Both methods produced similar results. Spinal input to the parabrachial nucleus was bilateral, with a slight contralateral predominance. The termination area was localized predominantly in the dorsal part of the lateral parabrachial nucleus, with additional limited terminations in the Kölliker-Fuse subnucleus. Projections from different rostrocaudal levels of the spinal cord overlapped completely, suggesting that spinal input to the parabrachial nucleus is not topographically organized. Taking these results together with those of others indicating that spinal input to the parabrachial nucleus arises primarily from nociceptive-specific neurons in lamina I of the dorsal horn, it is concluded that the spinal projections to the parabrachial nucleus are likely to be involved in various generalized aspects of nociception.

Animals↗

PubMed1989

Spino-diencephalic relays through the parabrachial nucleus in the cat.

Previous studies have shown that the spinal input to the parabrachial nucleus (PBN) in the cat is limited to certain portions of its lateral division 8,21,45. The purpose of the present study was to determine some of the output targets of PBN neurons located within this spinal terminal domain by means of single, double and triple light microscopic labeling strategies. Combinations of tracers included the retrograde transport of tritiated wheat germ agglutinin, wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) and Fluoro-Gold from the hypothalamus, amygdala or thalamus/zona incerta together with either the anterograde transport of WGA-HRP from the spinal cord or the degeneration of spinal terminals following spinal lesions. The results (summarized in Fig. 10) showed that the spinal terminal domain contains separable populations of neurons projecting to the thalamus/zona incerta and hypothalamus. Only a limited number of amygdala-projecting neurons was located in this domain. Evidence from several laboratories supports the conclusion that these potential spino-diencephalic relays are involved somehow in nociception. More information is needed, however, regarding differences in the response properties of these separable populations of spinal-recipient neurons before more specific hypotheses concerning the precise nature of their nociceptive functions can be formulated.

Animals↗

PubMed1989

Variations in the cellular incorporation of [3H]proline.

Injections of [3H]proline into various CNS nuclei in the cat and into the rat dorsal column nuclei labeled terminal targets of those regions despite the fact that only glia (and not neuronal somata) were labeled at the injection site. In contrast, although injections into cat CNS fiber tracts labeled glial cells surrounding the axons, neither the axoplasm, somata or terminals of those axons were labeled. In addition, injections into cat PNS dorsal root ganglia labeled ganglion cells. These results support previous findings suggesting that 3H-proline is incorporated into a class of molecules in the CNS (but not PNS) that is transferred from glia into neuronal somata (but not axoplasm).

Animals↗

PubMed1988

Afferent fibers supplying the uterus in the rat.

1. In the present three-part study electrophysiological techniques were used to characterize responses of afferent fibers in the rat hypogastric nerve to mechanical or chemical stimulation of the uterus, and anatomical techniques were used to identify the spinal segments through which uterine afferent fibers enter the spinal cord. 2. In an in vivo barbiturate-anesthetized preparation, hypogastric afferent fibers responded in a time-locked manner to mechanical stimulation confined to restricted regions of the uterus and adjacent ligament. Receptive fields were most often located on the uterine body, particularly over the cervix. The few located on the uterine horn were usually near regions irritated during preparative surgery. Effective mechanical stimuli (pressure, stretching, squeezing, probing, rarely contractions) were typically greater than 5 g and simultaneously accompanied by transient ischemia around the probe or contracted area. Distension, unless extreme, was not an effective stimulus. Retrospective analysis of the data indicated that fibers may be more sensitive to uterine stimulation when rats are in vaginal estrus/proestrus than in diestrus/metestrus. 3. In an in vitro preparation, hypogastric afferent fibers responded in a dose-dependent fashion to injections into the uterine artery of the algesic chemicals bradykinin, 5-hydroxytryptamine, and KCl. They also responded to high doses of CO2 (in saline) and NaCN, but rarely to lower doses. Nearly all fibers responded to more than one chemical with response characteristics unique to each chemical (e.g., latency, duration, peak rate). 4. Injections of horseradish peroxidase into the uterine body and small portions of the adjacent horns in rats in vaginal estrus consistently labeled a small number of cells in the L1-S1 dorsal root ganglia, with peaks at L2 and L6. Virtually no cells were labeled in rats whose estrous cycle had been disrupted (by inadvertently keeping them in constant light conditions for several weeks). 5. These results indicate that uterine afferent fibers travel to the central nervous system through both the hypogastric (e.g., L1-L4 ganglia) and pelvic (e.g., L5-S1 ganglia) nerves in the rat, and that hypogastric fibers are capable of conveying fairly precise information about temporal and spatial aspects of uterine mechanical and chemical stimulation. The results also encourage future research into the possibility that the responses of these fibers vary as a function of estrous stage or other aspects of the condition of the uterus (e.g., its irritation).(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1987

A glial-neuronal-glial communication system in the mammalian central nervous system.

Previous studies have demonstrated that when tritiated proline [( 3H]Pro) is injected into the dorsal column nuclei (DCN) of cats, it labels macroglial cells, but fails to label neurons at the injection site. (Tritiated leucine [( 3H]Leu) in contrast, labels both neurons and some glial cells.) Despite the failure of [3H]Pro to label DCN neurons, labeling is still observed in DCN terminal targets. This result suggests that glial cells are involved in the translocation of [3H]Pro-labeled molecules from one part of the brain to another. The purpose of the present experiment was to use electron microscopic autoradiographic techniques to characterize the labeling produced in internal arcuate fiber tract axons arising from DCN neurons 24 h after injections of [3H]Pro (or [3H]Leu, for comparison) into DCN. It was reasoned that, if the translocation of [3H]Pro-labeled molecules from DCN to its targets is indeed carried out by glial cells, then only glial elements associated with the fibers should be labeled following [3H]Pro injections of DCN. If, on the other hand, the translocation involves an initial transfer of [3H]Pro-labeled molecules into neuronal perikarya followed by axonal transport, then only axoplasmic elements along the fiber pathway should be labeled. Injections of [3H]Pro into DCN labeled axoplasmic elements in samples of axons from the internal arcuate tract both 'near' (0.5-0.8 mm) and 'far' (2-4 mm) from the injection site at about an equal absolute density. However, glial elements associated with the axons were also labeled in both samples, but much more densely in the 'near' than in the 'far' axons. Injections of [3H]Leu labeled axoplasm more densely than did [3H]Pro (by a factor of 4 in the 'far' samples). Glial labeling by [3H]Leu near the injection site was much less than that of [3H]Pro, but, 'far' from the injection, the levels of [3H]Leu and [3H]Pro glial labeling were comparable. Taken together with the results of other studies, these data support the existence of a previously unrecognized system of communication between glial cells and neurons. In this putative system (Fig. 9), molecules containing both [3H]Leu and [3H]Pro are transferred from glial cells into adjacent neuronal soma and transported down the length of the axon where, all along the way, some of them are transferred from the axon into adjacent glial processes. The system is more readily apparent when [3H]Pro is used because of its avid and preferential uptake by glial cells. Potential functions of such a system are unknown, but could be trophic, protective and/or informative.

Animals↗

PubMed1987

Differences in the efficiency and pattern of incorporation of [3H]leucine and [3H]proline into proteins of adult cat brain.

Previous EM autoradiographic studies have shown that injection of [3H]proline ([3H]Pro) into the cat dorsal column nuclei (DCN) results in heavy labeling of macroglia but negligible labeling of DCN neurons. [3H]Leucine ([3H]Leu), in contrast, was extensively incorporated into both neurons and glia. We now report preliminary assessment of differences in molecular labeling patterns produced by the two amino acid precursors in DCN injection sites (24 h following injection; equal amounts of [3H]Pro and [3H]Leu of equal specific radioactivity). [3H]Pro, despite its lack of incorporation into neurons, labeled DCN to a significantly greater extent than [3H]Leu (30.0 dpm/micrograms protein/microCi for [3H]Pro vs 11.7 dpm/micrograms protein/microCi for [3H]Leu). Greater than 90% of the radioactivity from both precursors was recovered in protein as opposed to TCA soluble or ethanol soluble molecules. Of the [3H]Pro- or [3H]Leu-derived radioactivity recovered in protein, greater than 94% was found to remain in the original precursor form. Fluorographic analysis of SDS acrylamide gels showed labeling of a wide variety of individual proteins with either amino acid. However, particular molecular weight classes were relatively more heavily labeled with either [3H]Leu (47, 63, 77 kDa) or [3H]Pro (22, 45, 50, 66, 80 kDa). Overall the results indicate that the difference in cellular distribution of incorporated [3H]Pro and [3H]Leu, as observed by EM autoradiography is a reflection of the extent of labeling and specific labeling pattern of proteins isolated from the tissue.

Animals↗

PubMed1986

Output systems of the dorsal column nuclei in the cat.

Numerous authors have demonstrated that the dorsal column nuclear complex (DCN) is functionally heterogeneous and has multiple terminal targets throughout the neuroaxis. In order to increase understanding of the functional significance of DCN's divergent connections, the present study used single and double light microscopic retrograde tracing strategies in the cat to characterize the location and morphology of DCN neurons that project to different portions of the diencephalon, rostral mesencephalon and spinal cord. These neuronal populations were then compared with those (previously reported from this and other laboratories) that project to the caudal mesencephalon, pons, inferior olive and cerebellum. When the results are considered together, a tentative picture of DCN emerges in which a population of clustered neurons that project exclusively to VPL form a core that is surrounded by and infiltrated with neurons projecting to other parts of the nervous system. Although the neuronal populations projecting to each of the different targets were individually separable anatomically by their location and/or morphological characteristics, previously reported physiological and other anatomical evidence permitted a preliminary grouping of these populations into 3 main systems. The first, a sensory tactile and kinesthetic 'cortical' system, consisted of 3 components: a double core of round, clustered medium-sized neurons (one each in the gracile and cuneate nuclei) and a variform rostral group projecting to the ventroposterolateral nucleus (VPL), a ventral group of unclustered large round neurons in the middle cuneate nucleus and a dense group of neurons in nucleus Z projecting to VPL's border with the ventrolateral nucleus (VPL/VL), and a group of mainly small-sized neurons located between the clusters of neurons or in the thin dorsal rim around the caudal and middle portions of the double cores and a populous, variform rostral group projecting indirectly (and possibly directly) to the posterior group through the intercollicular region of the tectum. The second, a sensorimotor 'cerebellar' system, consisted of multiple, subtly separable populations of neurons with different morphological characteristics all of which were located in different parts of the complex region that surrounds the cores on all sides. These neurons projected to restricted portions of interconnected targets within the zona incerta, tectum, pretectum, red nucleus, pontine grey, pontine raphe, inferior olive, and cerebellum.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1986

Specific somatic sensory relays in the mammalian diencephalon.

There are five major domains within the diencephalon that receive input from ascending somatic sensory pathways serving the limbs, trunk and viscera. These domains include the ventroposterolateral nucleus (VPL), the posterior group complex (PO), the zona incerta (ZI), the intralaminar complex and the thalamic reticular nucleus. Of these five domains, VPL is commonly considered a "specific" somatic "relay". The reasons for this view are that VPL receives dense, synaptically secure and precisely organized input from the equally precisely organized dorsal column nuclei (DCN), that most of VPL's neurons have small, unimodal cutaneous receptive fields which reflect their input from DCN, and that these neurons project this information in a precise way to the somatic sensory cortex. Several lines of evidence suggest that this rather simple view of VPL be modified. First, not only does VPL receive complex patterns of partially converging input from other ascending somatic pathways besides the DCN, but the pattern of its input from DCN appears to be more complex than once thought. Second, such input convergence and complex connective patterns also occur within PO and ZI (although the characteristics of the patterns differ between the three domains). Third, the response properties of neurons within VPL differ in its different parts and are not necessarily precise mirrors of the response properties of neurons within DCN. Fourth, although the responses of neurons in PO on the whole differ from those in VPL, there are some similarities. The same conclusion may prove true for neurons in the DCN-recipient portion of ZI.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗