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PubMed2004

[Effects on erectile function of transplanted major pelvic ganglion into the corpus cavernosum of adult rats with bilateral cavernous nerve injury].

OBJECTIVE: To investigate the effects on erectile function of transplanted major pelvic ganglion into the corpus cavernosum of adult male rats undergoing transection of bilateral cavernous nerves. METHODS: Twenty-six male Sprague-Dawley rats (3 - 4 month-old and 300 - 400 g/each) were divided into 2 groups: experimental group (transection of bilateral cavernous nerves and transplantation of left ganglion into left crus of penis, n = 16) and control group (transection of bilateral cavernous nerves only, n = 10). Erectile function was measured by injecting APO, and intracavernous pressure was measured 1 and 3 months afterwards by electric-stimulating the right major pelvic ganglion or the left crus. Half animals in each group were sacrificed 1 and 3 months afterwards for detecting nNOS-containing nerve fibers of corpus cavernosum. Electron microscopy of the implanted area was performed to assess neuronal survival. RESULTS: Both of the two groups have no erectile response to APO injection. Electrostimulation on the right major pelvic ganglion and left crus failed to produce erection in experimental group. The mean pressure changes in the two groups, measured by stimulating the left crus, were (9.41 +/- 3.20) and (4.16 +/- 2.58) cmH(2)O 1 month afterwards, and (13.67 +/- 4.18) and (5.09 +/- 2.74) cmH(2)O 3 months afterwards, respectively (P < 0.05). An increased number of nNOS-containing nerve fibers in left crus was detected in experimental group 1 and 3 months later, compared with control one (218.7 +/- 24.5, 18.0 +/- 3.7; 183.2 +/- 19.7, 19.0 +/- 3.8; P < 0.05). Ultrastructure examination by transmission electron microscope confirmed the survival of the implanted ganglion. CONCLUSION: Major pelvic ganglion can survive in the corpus cavernosum, and it has significant effects on the number of nNOS-containing nerve fibers and the alteration of intracavernous pressure.

Animals↗
PubMed1989

Peripheral target regulation of dendritic geometry in the rat superior cervical ganglion.

Dendritic arborizations of neurons in the adult rat superior cervical ganglion were measured in control ganglia and in ganglia innervating peripheral targets that were relatively larger or smaller than normal. The relative size of the target--the submandibular gland in these experiments--was manipulated during development by changing the ratio between the amount of target tissue and the number of innervating ganglion cells. Thus, ligating the submandibular salivary duct reduced the size of the gland, whereas partially denervating the gland produced a relatively larger target by making a smaller number of ganglion cells innervate a gland of normal size. Neurons innervating targets that were smaller than normal had significantly smaller dendritic arborizations and cell bodies than control cells. Conversely, neurons projecting to relatively larger than normal targets had larger dendritic arborizations and cell bodies, and more primary dendritic branches. Such cells were also innervated by a larger than normal number of preganglionic inputs. A similar change in dendritic geometry was observed when relative target size was increased after cutting the cervical sympathetic trunk, showing that target regulation of dendritic geometry is not dependent on ganglion cell activity or the presence of presynaptic innervation. Dendrites in the superior cervical ganglion normally grow in parallel with body size throughout life (Purves et al., 1986a; Voyvodic, 1987a). The present results imply that an important aspect of dendritic growth is an ongoing responsiveness of ganglion cells to feedback signals arising from the peripheral targets they innervate.

Animals↗
PubMed1987

Effect of dopamine receptor activation on ganglionic transmission and cyclic AMP levels in the stellate ganglia and renal arteries of the dog.

By using selective dopamine (DA) receptor agonists and antagonists, we have demonstrated previously the presence of DA-2- and DA-1-like DA receptors in the stellate ganglia of the dog. Activation of either DA-2- or DA-1-like receptors by quinpirole or fenoldopam, respectively, leads to inhibition of ganglionic transmission. In the present study we have examined the involvement of DA receptor subtypes in the action of DA on ganglionic transmission. Inasmuch as stimulation of DA receptors is linked to the activation (DA-1) or inhibition (DA-2) of the enzyme adenylate cyclase, we have also measured the accumulation of cyclic AMP (cAMP) for biochemical characterization of ganglionic DA receptors. In isolated stellate ganglia treated with phentolamine and propranolol, DA caused concentration-dependent inhibition of ganglionic transmission as evidenced by reductions in the amplitude of the evoked postganglionic compound action potentials. The inhibitory effect of DA on ganglionic transmission was antagonized by both the DA-1 receptor antagonist, R-sulpiride, and the DA-2 receptor antagonist, S-sulpiride. However, the more potent and selective DA-1 receptor antagonist, SCH-23390, failed to antagonize the DA-induced inhibition of ganglionic transmission. Isolated stellate ganglia were also utilized for the measurement of cAMP. Neither DA nor the selective DA-1 receptor agonist, fenoldopam, caused any significant changes in cAMP, suggesting the lack of an adenylate cyclase-linked DA-1 receptor in the ganglia. On the other hand, beta adrenoceptor activation by isoproterenol produced a 3-fold increase in cAMP content of the stellate ganglia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Catecholaminergic properties of cholinergic neurons and synapses in adult rat ciliary ganglion.

Parasympathetic neurons of the ciliary ganglion are innervated by preganglionic cholinergic neurons whose cell bodies lie in the brain stem; the ganglion cells in turn provide cholinergic innervation to the intrinsic muscles of the eye. Noradrenergic innervation of the iris is supplied by sympathetic neurons of the superior cervical ganglion. Using immunocytochemical and histochemical techniques, we have examined the ciliary ganglion of adult rats for the expression of cholinergic and noradrenergic properties. As expected, the postganglionic ciliary neurons possessed detectable levels of choline acetyltransferase immunoreactivity (ChAT-IR). Unexpectedly, many ciliary neurons also exhibited immunoreactivity for tyrosine hydroxylase (TH-IR). Some had dopamine beta-hydroxylase-like (DBH-IR) immunoreactivity, but none contained detectable catecholamines, even after treatment with nialamide and L-DOPA. A sparse plexus of fibers exhibiting faint TH-IR was present in the irises of acutely sympathectomized rats. The terminals of preganglionic axons in the ciliary ganglion exhibited not only immunoreactivity for ChAT, but also for TH and contained stores of endogenous catecholamine. Neither ciliary neurons nor their preganglionic innervation accumulated detectable stores of exogenous catecholamines. Rats sympathectomized as neonates by treatment with 6-hydroxydopamine subsequently had a greater proportion of neurons possessing detectable TH-IR in the ciliary ganglion; both the TH-IR perikarya and their axons in the iris were more intensely immunofluorescent. TH-IR was present in the ciliary neuron cell bodies of mouse, guinea pig, and ferret. These species, however, lacked detectable TH-IR or catecholamine stores in preganglionic terminals. These observations indicate that mature, functionally cholinergic neurons from 2 different embryonic origins, postganglionic ciliary neurons derived from the neural crest and preganglionic neurons derived from the neural tube, display several catecholaminergic properties.

Animals↗
PubMed1985

gamma-Aminobutyric acid receptors on chick ciliary ganglion neurons in vivo and in cell culture.

In the chick ciliary ganglion, preganglionic terminals maintain cholinergic synapses on the choroid neurons and both cholinergic and electrical synapses on the ciliary neurons. The preganglionic terminals also contain enkephalin- and substance P-like immunoreactivity, suggesting that transmission through the ganglion is more complicated than is indicated by the known synaptic connections. We report here that embryonic chick ciliary ganglion neurons also have gamma-aminobutyric acid (GABA) receptors and that GABA applied to the ganglion can block transmission elicited by preganglionic stimulation. Studies on the neurons in cell culture indicate that the GABA response is mediated by GABAA receptors: GABA activates a Cl- conductance, and the response can be mimicked by muscimol and blocked by bicuculline or picrotoxin. The GABA receptors are regulated independently from acetylcholine (ACh) receptors on the neurons since the levels of ACh and GABA sensitivity are influenced differently by culture age and by chronic exposure to GABA or elevated K+ concentrations. Application of GABA to intact ciliary ganglia increases the membrane conductance of ganglionic neurons (as in culture), reduces to subthreshold the amplitude of excitatory postsynaptic potentials in the neurons elicited by preganglionic stimulation and completely blocks transmission through the ganglion. A native source of ligand for the receptors in vivo has yet to be identified.

Acetylcholine↗
PubMed1987

Biochemical and immunocytochemical characterization and distribution of phosphorylated and nonphosphorylated subunits of neurofilaments in squid giant axon and stellate ganglion.

Monoclonal antibodies to squid neurofilament (aNFP) and intermediate filament (aIFA) proteins were used as probes for the biochemical and immunocytochemical analyses of neurofilament structure and distribution in the squid giant axon and stellate ganglion. On Western blots the aNFP antibody stained exclusively the 220 kDa and high-molecular-weight (HMW) components of neurofilaments in the giant axon, whereas the aIFA antibody primarily labeled the 60 kDa protein in the giant axon and the 60 and 65 kDa proteins in the stellate ganglion. Dephosphorylation of axoplasmic proteins by alkaline phosphatase resulted in a decrease in the molecular weights of both the 220 kDa and HMW neurofilament proteins and a concomitant loss of reactivity with the aNFP antibody on Western blots. This indicated that the aNFP antibody is specific for a phosphorylated epitope in the neurofilament. Increased dephosphorylation of the 220 kDa protein led to an enhanced immunostaining of the resultant 190 kDa polypeptide by the aIFA antibody, suggesting that the phosphorylated epitope may mask the conserved epitope recognized by aIFA. Light and electron microscopic immunocytochemical studies show intense labeling by the aNFP antibody in the giant axon. In contrast, the aIFA antibody labeled the glial cells around the giant axon intensely, while labeling of the giant axon itself was considerably less than that with the aNFP antibody. Since the 60 kDa protein in axoplasm is intensely stained by the aIFA antibody on Western blots, the relatively low amounts of labeling seen on semithin and thin sections of the giant axon by this antibody may be due to the masking of the 60 kDa protein by in situ fixed axoplasmic proteins. However, the aIFA antibody intensely labeled glial cells within the stellate ganglion and "islands" of filaments and nuclear membranes within ganglion cells. No reactivity for either antibody was seen in synapses. The aNFP antibody specifically labeled "beadlike" portions and cross-bridges on the axonal neurofilaments, suggesting that these components consist of the 220 kDa and HMW proteins. In contrast, the aIFA antibody labeled relatively smooth filaments in ganglion and glial cells. These data suggest that the 65 kDa protein represents the squid glial filament protein and that the 60 kDa protein found in axoplasm represents the low-molecular-weight subunit in the axonal neurofilament. The latter appears to be formed and/or organized in "islands" of filaments within ganglion cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

The otic ganglion and its neural connections in the rat.

The precise localisation of the rat otic ganglion and its neuronal connections, particularly those related to salivation, has been established by means of dissection and from a study of histological sections taken serially through the head. The otic ganglion lies medial to the pterygopalatine branch of the internal carotid artery and beneath the trigeminal ganglion from which it is separated by the sphenoid bone. In the rat there is no direct connection between the glossopharyngeal nerve and the otic ganglion, as is the case in man. However, a neural connection between the facial nerve and the otic ganglion and a further connection linking the glossopharyngeal with the facial nerve through which the salivatory axons may pass to reach the otic ganglion is described. A comparison is made of the neural pathways involved in parotid secretion in the rat with those believed to exist in man.

Animals↗
PubMed1987

Growth and morphogenesis of an autonomic ganglion. I. Matching neurons with target.

Regulation of the number and size of neurons presumably plays a role in the matching of a group of neurons to their target. In this paper the relationship of the cardiac ganglion neurons of the frog to their target is examined. Neurons in this ganglion first appear in the embryo and continue to accumulate for several months, even after the animal has completed metamorphosis, and eventually reach a fixed number of cells in the adult. This prolonged period of neuron production has provided an opportunity to manipulate development and test various mechanisms of neuronal regulation. Manipulation of animal culture conditions and hormone levels has shown that the addition of neurons to the ganglion continues up to the characteristic adult number and depends upon neither the chronological age nor the developmental stage of the animal. The size of neurons also changes markedly during development. The average cell body size initially decreases due to the addition of many smaller cells to the ganglion. After metamorphosis neuron size increases dramatically. The changes in size and number complement one another such that the total volume of neuronal cell bodies increases in proportion with the size of both the target and the entire body. The relationship holds for changes in animal size that extend over 4 orders of magnitude and follows a power function of the form y = bxm. Regulation of cardiac ganglion size can be divided into 3 overlapping phases: (1) the arrival of neurons and precursors from the neural crest, (2) an increase in neuron number, (3) and an increase in neuron size. A common denominator for all phases is that the size of the ganglion is, in a coherent way, precisely matched to the size of its target.

Acetylcholinesterase↗
PubMed1986

Arterial supply of the rat superior cervical ganglion: a morphological and semiquantitative histochemical investigation.

A combination of morphological and semiquantitative techniques has been employed to characterise the arterial supply to the rat superior cervical ganglion. Microfil and ink-injected preparations indicate that the major supply is from the carotid body artery which sends several branches to the rostral part of the ganglion and a recurrent branch to its caudal part. Occlusion of the proximal part of the external carotid artery, and hence the carotid body artery (whether it be derived from the external carotid or occipital artery), produces a dramatic reduction in neuronal succinate dehydrogenase activity within 30 minutes. In contrast, section of the preganglionic trunk and vagus nerves--whose vascular beds are seen to anastomose with that of the superior cervical ganglion--results in no observable change in ganglion activity. It is concluded that the carotid body artery is the only significant artery of supply to the rat superior cervical ganglion and therefore that preganglionic neurectomies can be carried out without risk of anoxia to the neurons of the ganglion.

Animals↗
PubMed1977

[Influence of different fixation buffers on the quantitative cytoarchitecture of the cochlear spiral ganglion. A morphometric study (author's transl)].

The influence of two fixation buffers on the quantitative cytoarchitecture of the cochlear spiral ganglion in guinea pigs was evaluated morphometrically. After fixation with phosphate buffered 1.3% OsO4 granular spiral ganglion cells lost 45% of their average individual volume as compared to the volume after fixation with s-collidine buffered 1.3% OsO4. Using the two fixatives there was no significant difference of the volume proportion of cell nuclei, mitochondria, lysosomes and rough endoplasmic reticulum per unit volume cytoplasm of the granular spiral ganglion cells. The volume proportion of their ribosomes and their Golgi apparatus per unit volume cytoplasm increased 3.5fold after fixation with phosphate buffered OsO4. The volume density of the granular ganglion cells decreased by 30%, the volume density of the interganglionar space (= space between granular ganglion cells) showed an increase of 50% using phosphate buffer. Mostly the extracellular space was participating in this relative increase of the interganglionar space. As a result fixation of the spiral ganglion for morphometric studies should be performed using s-collidine buffered OsO4. The morphometric findings underline the presumption of semicompact myelin being a fixation artefact.

Animals↗
PubMed1984

Inhibitory presynaptic effect of noradrenaline on the hypogastric ganglion of the guinea pig.

The effect of noradrenaline on the hypogastric ganglion of the guinea pig was studied to establish the role of catecholamine-containing sites in the sympathetic ganglia with the hypogastric nerve-vas deferens preparation. In these experiments the ganglion was separated pharmacologically from the muscle by a partition. An application of noradrenaline, adrenaline and isoproterenol each to the ganglion inhibited a twitch response of the vas deferens to preganglionic nerve stimulation at low frequencies. The drug effect decreased with increasing frequencies of stimulation. The inhibitory action of these drugs was antagonized by phentolamine, but not by propranolol. Clonidine also reduced the response to the nerve stimulation in a similar manner as did catecholamines, and the inhibitory action was antagonized by phentolamine. In contrast, phenylephrine had no significant action. The inhibitory effect of noradrenaline and clonidine was antagonized by the alpha-2 antagonist yohimbine, but not by such alpha-1 antagonists as prazosin and E-643. Noradrenaline did not affect the ganglion-stimulating action of acetylcholine. These results suggest that the inhibitory action of noradrenaline may be mediated by alpha-2 adrenoceptors on presynaptic cholinergic nerve endings of the guinea-pig hypogastric ganglion. These data are discussed in relation to the presence of noradrenaline-containing sites in this ganglion.

Acetylcholine↗
PubMed1982

Trans-synaptic modulation via muscarinic receptors of serotonin-containing small intensely fluorescent cells of superior cervical ganglion.

Verhofstad et al. (Verhofstad, A. A. J., H. W. M. Steinbusch, B. Penke J. Varga, and H. W. J. Joosten (1981) Brain Res. 212: 39-49) have reported that serotonin of the rat superior cervical ganglion is contained in a distinct and separate population of small intensely fluorescent (SIF) cells. We provide evidence that the serotonin-containing SIF cells are modulated, in part, by preganglionic cholinergic neurons. For example, administration of the muscarinic agonists carbachol or oxotremorine increases the content of serotonin, and the increase induced by oxotremorine is blocked by atropine. Treatment with atropine alone or decentralization of the ganglion lowers the content of serotonin. From the rate of accumulation of serotonin in the ganglion after the administration of the monoamine oxidase inhibitor pargyline, it appears that the rate of formation of serotonin is increased after oxotremorine treatment. Reserpine, p-chlorophenylalanine, or fluoxetine treatment reduces the content of serotonin in the ganglion, suggesting that the SIF cell system has properties similar to those of serotonergic neurons of the brain. We postulate that the serotonin-containing SIF cells of the rat superior cervical ganglion participate in local circuit modulation of ganglionic transmission by receiving preganglionic information via muscarinic receptors.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1983

Axonal sprouts of the hypoglossal nerve implanted in the superior cervical ganglion of adult rats establish synaptic contacts under long-lasting GABA effect. An experimental degeneration study.

Experimental degeneration was used in this study to determine if the hypoglossal nerve implanted already in the superior cervical ganglion of adult rat under GABA treatment has established morphologically-identifiable synapses with the dendrites of principal ganglion cells. The implanted hypoglossal nerve trunk was cut in a re-operation, and the ganglionic samples were studied by electron microscopy after 0, 6, 12, 24 and 48 h survival times. First signs of degenerative changes were found in the myelinated and non-myelinated axons alike, 6 h after axotomy. The fine-structural signs of degeneration resembled those of the preganglionic nerve fibres. Degenerating nerve terminals establishing synaptic contacts with the dendrites of the principal ganglion cells were also seen, indicating that the axonal sprouts of the implanted hypoglossal nerve established synaptic contacts with the ganglion cells. It remained, however, to be elucidated whether or not these synapses of the hypoglossal nerve are functionally active contacts while the preganglionic innervation is also present within the ganglion.

Animals↗
PubMed1981

The distal vagal ganglion of the hen (Gallus domesticus). A histological and physiological study.

The distal vagal ganglion of the hen was examined histologically and physiologically. The number of neurons in the right and left distal vagal ganglia were counted and a mean figure of 6710 neurons obtained. The proportions of the different types of neuron present were determined and their size measured. No multipolar cells with boutons on them were found. Morphologically the ganglion is sensory. Following chronic vagotomy proximal to the distal vagal ganglion the vagus nerves were stimulated and the effect on the heart and gastrointestinal tract monitored. It was found that stimulation of the acutely sectioned nerve caused a drop in heart rate and an increase in gastrointestinal activity. There was no cardiac or gastrointestinal response when the chronically operated nerve was stimulated. Physiologically the ganglion is sensory. The evidence is reviewed for homology between inferior vagal ganglion of the mammal and the distal vagal ganglion of the hen.

Animals↗
PubMed1981

Density, soma size, and regional distribution of rabbit retinal ganglion cells.

Cell soma area or diameter distributions are generally very skewed and present some unusual problems in characterization and description. In this study of ganglion cell soma size in rabbit retina, our conclusions are based on a statistical method which not only characterizes this particular neuronal population but which also may be of considerable value in other species and other parts of the nervous system. To facilitate comparisons between retinas, we used ganglion cell density as the measure of retinal location. The rabbit retina has a horizontally extended area centralis, the visual streak, which we show to have a uniformly high peak cell density along most of its length. Cell density maps were used to estimate the total number of ganglion cells in the retina; the mean for three retinas was about 406,000 cells, which corresponds well to an earlier count of optic nerve axons (394,000 +/- 20,000; Vaney, D.I., and A. Hughes (1976) J. Comp. Neurol. 170: 241-252). Contrary to other reports, we could not find any large differences in ganglion cell size distributions between the inferior peripheral retina and the visual streak nor could we confirm the report of a large cell area temporalis (Provis, J. M. (1979) J. Comp. Neurol. 185: 121-138). Cell size distributions in the superior and inferior retina were very different, however, and, within the inferior retina, there was a small but systematic change in cell size between the periphery and the visual streak. In general, small and medium size cells were present in nearly constant proportions throughout the inferior retina, while the large ganglion cells showed a small decrease in proportion from the periphery to the visual streak; the decline in large cells was a linear function of cell density. In terms of ganglion cell soma size, there was no sharp distinction between the visual streak and the peripheral retina.

Animals↗
PubMed1981

Anatomy of the cerebral ganglion in Oligacanthorhynchus tortuosa (Acanthocephala) from the opossum (Didelphis virginiana).

The anatomy of the cerebral ganglion from Oligacanthorhynchus tortuosa (Acanthocephala) resembles that previously described for large acanthocepalans from mammals. The cell population was equally distributed between each half of the ganglion, there were 38 cells on each side with seven cells centrally located. The core of the ganglion or neuropile occupied the central part of the ganglion and was the site for the crossover for many cell processes. Many of the axons from these cells exited from the side opposite the soma. The cell bodies predominated on the ventral surface while the dorsal surface was more of a mixture of cell bodies and neurites. The cytoarchitecture of these cells varied considerably but most had a large round nucleus with well-defined nucleoli. There were 83 cells, two of which were binucleate. The two binucleate cells were located at opposite extremes of the anteroposterior axis of the ganglion. The anterior binucleate cell was adjacent to the dorsal surface whereas the posterior cell was central and near the posterior terminal of the ganglion.

Acanthocephala↗
PubMed1995

Synapses of biplexiform ganglion cells in the outer plexiform layer of the retina in Xenopus laevis.

Following retrograde transport of horseradish peroxidase from the optic nerve to the retina in Xenopus laevis, biplexiform ganglion cell were revealed. Their synaptic association with the other elements of the outer plexiform layer (OPL) were studied in serial ultrathin sections. The dendrites in the OPL of two regrogradely labelled biplexiform ganglion cells (GC1 and GC2) were completely reconstructed from the sections. Both cells had similar dendritic field sizes (0.026 and 0.025 m2, respectively) in the OPL, and received a few dozens of synapses (GC1: 39, GC2: 56) synapses. None of the ganglion cell dendrites were found in presynaptic position. Of the synapses, 10 derived from rods, 22 from cones and 7 from horizontal cells to GC1 and 13 from rods, 32 from cones and 10 from horizontal cells to GC2. Synapses were seen neither between interplexiform cell axons and biplexiform ganglion cell dendrites nor bipolar and biplexiform ganglion cell dendrites in the OPL. These observations indicate that the dendrites of biplexiform ganglion cells preferentially but not exclusively receive synapses from photoreceptor cells in the OPL.

Animals↗
PubMed1994

Target tissues and innervation regulate the characteristics of K+ currents in chick ciliary ganglion neurons developing in situ.

The expression of appropriate ensembles of ionic channels is necessary for the differentiation and normal function of vertebrate neurons. Cell-cell interactions may regulate the expression and properties of ionic channels in embryonic neurons. Previous studies have shown that the expression of A-type K+ channels (IA) and Ca2+-activated K+ channels (lK[Ca]) is abnormal in chick ciliary ganglion neurons developing in vitro in the absence of normal cell-cell interactions. Other voltage-activated currents develop normally under these conditions. The present studies were designed to establish the role of the target tissues and the preganglionic innervation in regulating the expression of these currents in embryonic chick ciliary ganglion neurons developing in situ. Surgical manipulations were used to remove the developing optic vesicle, which contains the target tissues, the mid-dorsal region of the midbrain primordium, which contains the preganglionic nucleus, or both, all prior to the formation of the ciliary ganglion. IA and IK[Ca] were then examined in acutely isolated neurons that developed in ovo in the presence (OV+) or absence (OV-) of the normal target tissues, in the presence (MB+) or absence (MB-) of preganglionic innervation, and in the absence of both preganglionic innervation and target tissues (OV-/MB-). The amplitude of IA was unaffected by the operations. However, the activation and inactivation kinetics of IA were two- to threefold faster in OV- or OV-/MB- cells compared to neurons isolated from control OV+ ganglia at embryonic days 11-14 (E11-E14). There were no changes in the voltage dependence of activation or steady-state inactivation, or in the time course of recovery from inactivation. By contrast, neurons isolated from MB- ganglia expressed an IA with amplitude, voltage dependence, and kinetics that were indistinguishable from those of control MB+ and OV+ ganglia. Therefore, interactions with target tissues in the eye play a role in determining the characteristics of IA in developing ciliary ganglion neurons, whereas preganglionic innervation does not. Furthermore, the amplitude of IK[Ca] was reduced by 90-100% in OV-, MB-, and OV-/MB- neurons isolated at E12-E14 as compared to MB+ and OV+ controls. Voltage-activated Ca2+ currents were present at normal amplitudes in all of these neurons. Thus, the expression of IK[Ca] in chick ciliary ganglion neurons is regulated by both target tissue interactions and preganglionic innervation. Therefore, cell-cell interactions are necessary for the expression of a normal ensemble of ionic channels in chick ciliary ganglion neurons developing in situ.

Animals↗