[Characteristics of the autonomic nervous system state in children with myopia associated with undifferentiated connective tissue dysplasia].

Autonomic nervous system disorders occur in 100% cases in patients with connective tissue dysplasia. Biomechanism of accommodation and autonomic innervation of ciliary body was not investigated clearly and presented as area of further research. The goal of the study was to evaluate features of autonomic nervous system in patients with myopia associated with connective tissue dysplasia. 50 children with myopia associated with connective tissue dysplasia went through ophtholmological examination. To evaluate function of autonomic nervous system all patients were observed with the machine "Valenta" which has ECG recording. As a result we found that children with myopia and connective tissue dysplasia have unsatisfactory adaptive reserves with imbalance of sympathetic and parasympathetic input, autonomic nervous system wasn't available to provide homeostasis in demanding level. We hypothesized that autonomic nervous system might be a reason which lead to disorders in process of accommodation during myopia and assist its progressing.

Transient internal ophthalmoplegia after inferior oblique myectomy.

Internal ophthalmoplegia causing pupillary dilatation and loss of accommodation following damage to the ciliary ganglion is a rare complication of strabismus surgery. Here we report a case of parasympathetic neuropraxia resulting in transient internal ophthalmoplegia after inferior oblique myectomy in a 12-year-old girl. Short-term symptomatic relief was achieved with 1% pilocarpine. Normal visual function returned over several months.

Adenine nucleotide effect on intraocular pressure: Involvement of the parasympathetic nervous system.

Nucleotides are present in the aqueous humor possibly exerting physiological effects on intraocular pressure (IOP). To determine the effect of nucleotides such as ATP and its related derivatives on IOP, New Zealand white rabbits were used. IOP was measured in rabbits treated topically either with saline (control) or with a single dose (10 microg/microL) of adenine nucleotides (ATP, 2-meS-ATP, ATP-gamma-S, alpha,beta-meADP, alpha,beta-meATP and beta,gamma-meATP). Those nucleotides reducing IOP (alpha,beta-meATP and beta,gamma-meATP) were then tested in concentrations ranging from 1 to 100 microg/microL to obtain the IC(50) value. Several antagonists for the P2 and adenosine A1 receptors (all at 10 microg/microL) were assayed 30 min before the application of the hypotensive nucleotide beta,gamma-meATP. To see whether the nucleotide was acting directly on the structures involved in aqueous humor dynamics or on the autonomic nerves controlling IOP, animal denervation and sympathetic (yohimbine and ICI-118,551 at 10 microg/microL) and parasympathetic (atropine and hexametonium at 10 microg/microL) receptors' antagonists were used 30 min before the instillation of beta,gamma-meATP. alpha,beta-meATP and beta,gamma-meATP decreased IOP to 60% of control value (basal IOP=23.2+/-1.3 mmHg), with IC(50) of 1.59+/-0.21 microg/microLand 0.56+/-0.62 microg/microL, which corresponds to 3mM and 1mM respectively. Denervation completely abolished the effect of beta,gamma-meATP. Sympathetic antagonists did not modify the hypotensive effect of beta,gamma-meATP, but parasympathetic antagonists were able to abolish it. Among the series of adenine nucleotide tested, alpha,beta-meATP and beta,gamma-meATP presented hypotensive actions on IOP. beta,gamma-meATP seems to stimulate cholinergic terminals being its final effect the IOP reduction. Therefore, these two nucleotides are interesting pharmacological tools for those pathologies related with high intraocular pressure.

Effect of hydrogen sulfide on sympathetic neurotransmission and catecholamine levels in isolated porcine iris-ciliary body.

In the present study, we investigated the pharmacological action of hydrogen sulfide (H2S, using sodium hydrosulfide, NaHS, and/or sodium sulfide, Na2S as donors) on sympathetic neurotransmission from isolated, superfused porcine iris-ciliary bodies. We also examined the effect of H2S on norepinephrine (NE), dopamine and epinephrine concentrations in isolated porcine anterior uvea. Release of [3H]NE was triggered by electrical field stimulation and basal catecholamine concentrations was measured by high performance liquid chromatography (HPLC). Both NaHS and Na2S caused a concentration-dependent inhibition of electrically evoked [3H]NE release from porcine iris-ciliary body without affecting basal [3H]NE efflux. The inhibitory action of H2S donors on NE release was attenuated by aminooxyacetic acid (AOA) and propargyglycine (PAG), inhibitors of cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE), respectively. With the exception of dopamine, NaHS caused a concentration-dependent reduction in endogenous NE and epinephrine concentrations in isolated iris-ciliary bodies. We conclude that H2S can inhibit sympathetic neurotransmission from isolated porcine anterior uvea, an effect that is dependent, at least in part, on intramural biosynthesis of this gas. Furthermore, the observed action of H2S donors on sympathetic transmission may be due to a direct action of this gas on neurotransmitter pools.

Diurnal fluctuations and developmental changes in ocular dimensions and optical aberrations in young chicks.

PURPOSE: To investigate further the emmetropization process in young chicks by studying the diurnal fluctuations and developmental changes in the ocular dimensions and optical aberrations, including refractive errors, of normal eyes and eyes that had the ciliary nerve sectioned (CNX). METHODS: The ocular dimensions and aberrations in both eyes of eight CNX (surgery on right eyes only) and eight normal chicks were measured with high-frequency A-scan ultrasonography and aberrometry, respectively, four times a day on five different days from posthatching day 13 to 35. A fixed pupil size of 2 mm was used to analyze aberration data. Repeated-measures ANOVA was applied to examine the effects of age, time of day, and surgery. RESULTS: Refractive errors and most higher-order aberrations decreased with development in both normal and CNX eyes. However, although normal eyes showed a positive shift in spherical aberration with age, changing from negative spherical aberration initially, CNX eyes consistently exhibited positive spherical aberration. Anterior chamber depth, lens thickness, vitreous chamber depth, and thus optical axial length all increased with development. Many of these ocular parameters also underwent diurnal changes, and mostly these dynamic characteristics showed no age dependency and no effect of CNX. Anterior chamber depth, vitreous chamber depth, and optical axial length were all greater in the evening than in the morning, whereas the choroids were thinner in the evening. Paradoxically, eyes were more hyperopic in the evening, when they were longest. Although CNX eyes, having enlarged pupils, were exposed to larger higher-order aberrations, their growth pattern was similar to that of normal eyes. CONCLUSIONS: Young chicks that are still emmetropizing, show significant diurnal fluctuations in ocular dimensions and some optical aberrations, superimposed on overall increases in the former and developmental decreases in the latter, even when accommodation is prevented. The possibility that these diurnal fluctuations are used to decode the eye's refractive error status for emmetropization warrants investigation. That eyes undergoing ciliary nerve section have more higher-order aberrations but do not become myopic implies a threshold for retinal image degradation below which the emmetropization process is not affected.

Haploinsufficiency for Phox2b in mice causes dilated pupils and atrophy of the ciliary ganglion: mechanistic insights into human congenital central hypoventilation syndrome.

Dilp1 is a semi-dominant mouse mutation that causes dilated pupils when heterozygous and is lethal when homozygous. We report here that it is caused by a point mutation that introduces a stop codon close to the start of the coding sequence of the paired-like homeobox transcription factor Phox2b. Mice carrying a targeted allele of Phox2b also have dilated pupils and the two alleles do not complement. Phox2b is necessary for the development of the autonomic nervous system and when absent one of the consequences is that all parasympathetic ganglia fail to form. Constriction of the pupil is a parasympathetic response mediated by the ciliary ganglion and we find that in Phox2b heterozygous mutants it is highly atrophic. The development of other parasympathetic and sympathetic ganglia appears to be largely unaffected indicating that the ciliary ganglion is exquisitely sensitive to a reduction in dose of this transcription factor. PHOX2B has been implicated in human disease. Mutations, principally leading to polyalanine expansions within the protein, have been found in patients with congenital central hypoventilation syndrome (CCHS), the cardinal feature of which is an inability to breathe unassisted when asleep. Additionally, some CCHS patients have ocular abnormalities, including pupillary defects, although they principally have constricted rather than dilated pupils. The apparent phenotypic differences observed between mice carrying a loss-of-function mutation of Phox2b and CCHS patients indicate that PHOX2B mutations found in CCHS patients, all of which can produce proteins with intact DNA-binding domains, are gain-of-function mutations that alter rather than abolish protein function.

[Human and animal ciliary ganglion--history and modern conceptions]. / Resnichnyi uzel cheloveka i zhivotnykh--istoriia izucheniia i sovremennye kontseptsii.

This paper reviews one of the complicated problems of the anatomy of the autonomic nervous system--the structure of human ciliary ganglion (CG). The literature data as well as the results obtained by the department and personally by the authors, are analyzed in three aspects: (a) human CG external structure and topography; (b) CG anatomy in animals and (c) characteristic of neurocytes of human and animal CG. The evidence indicating the absence of sympathetic root in both humans and animals, is presented. The size, shape and topography of CG are interrelated by the features of morphogenesis, thus reflecting it: these parameters are associated with a different localization of neuroblasts--precursor cells for CG neurons in brachicephals and dolichocephals. Authors conclude, that the data obtained in animal experiments cannot be extrapolated to humans, not only due to their contradictory nature, but also because of the definite presence of CG sensory root in man.

Neural pathways subserving negative lens-induced emmetropization in chicks--insights from selective lesions of the optic nerve and ciliary nerve.

PURPOSE: Active emmetropization describes the process by which young eyes regulate their growth to eliminate refractive errors. The purpose of this study was to re-investigate the role of the brain in compensation to imposed hyperopic defocus (negative lenses), specifically, to assess whether a retina-brain link and/or an intact ciliary nerve are required for this emmetropizing response. Data from previous related studies are equivocal. METHODS: Unilateral lesion surgery involving either or both optic nerve section (ONS) and ciliary nerve section (CNS), was performed on 2-3 day old White-Leghorn chicks to interrupt communication between the eye (retina in the case of ONS) and brain. After a recovery period of 4 days, lesioned eyes were fitted with either -5 or -15 D lenses or diffusers (6-9 per group). An additional lesion group underwent unilateral CNS and was fitted with -5 D lenses bilaterally. Finally 3 groups that underwent the same unilateral optical treatments but no surgery were included as controls for analyzing lesion-induced changes. Complete sets of measurements, involving retinoscopy for refractive errors, and high frequency A-scan ultrasonography for axial ocular dimensions, were made at the beginning (baseline), and end of a 4 day treatment period. Additional ultrasonography data were collected after 1 and 2 days of treatment. Optical treatment effects were expressed as changes in interocular differences from baseline values. RESULTS: All three lesions produced hyperopic shifts in refraction (evident in baseline values), although this effect was minimal for the ONS+CNS group. Choroidal thickening as well as increased anterior chamber depth and lens thinning were observed in all cases but vitreous chamber depth was reduced in only the ONS group. In response to the -5 D lens, the control (nonlesioned) group showed nearly complete compensation, while full compensation was not achieved to the -15 D lens over this short treatment period. The diffuser group showed the largest change, which was also in the direction of myopia. Both the ONS and CNS groups showed near normal compensation, as indexed by the changes in refractive errors relative to their respective baseline values. In contrast, the ONS+CNS lens groups overcompensated, by 130% and 54% for the -5 D and the -15 D lens groups respectively. Form deprivation responses were slightly exaggerated in both ONS and ONS+CNS groups, the latter group again showing the largest response. Enhanced vitreous chamber growth was evident under all conditions and correlated well with the refractive changes across the groups. DISCUSSION: The data imply that an intact retina-brain link is not required for compensation to hyperopic defocus and thus emmetropization. However, the data also imply interactions between higher centers and the eye. The emmetropization set-point appears to be recalibrated after ONS surgery. The data also indicate a role of the ciliary nerve as an important conduit for signals that exercise a restraining influence on eye growth.

Distribution and organization of the nerve fiber and ganglion cells of the human choroid.

Antibodies to the 68, 160 and 200 kD of the neurofilament triplets were used to study the distribution and organization of neuronal structures in the human choroid. Choroidal axons were observed in the suprachoroid and vascular laminae but absent from the choriocapillary layer. Most axons were situated in the suprachoroid. In this layer, there were band-like bundles. The two thickest band-like bundles could constitute the long ciliary nerve, while the rest could constitute short ciliary nerves. These bundles ran through the suprachoroid, branching out on the suprachoroid and the vascular laminae until they reached the ciliary body. In the submacular area of the suprachoroid, the branches of the band-like bundles were so intermingled that they looked like a meshwork. In the vascular layer, the large vessels and their primary branches were accompanied by paravascular axons. Some paravascular axons penetrated the medium-caliber vessel layer and in the submacular area interwove to form a network parallel to the arteriole walls. In addition, perivascular axons were revealed by antibodies to neuropeptides. Choroidal ganglion cells were more numerous in the central choroid, specifically in a circumferential area corresponding to the entrance of the short posterior ciliary arteries and their primary branches, and in the vicinity of the submacular area. These cells presented bipolar and multipolar morphology. The high concentration of innervation in the central human choroid could be necessary to maintain strict blood flow in this zone; thus if required, these neuron structures could induce early vasodilation reflexes at the entrance of the choroidal blood vessels to increase the blood flow.

Characterization of nitrergic neurons in the porcine and human ciliary nerves.

PURPOSE: To further characterize a subpopulation of choroidal ganglion cells associated with the ciliary nerves. METHODS: Isolated long ciliary nerves of porcine and human eyes containing ciliary nerve-associated ganglion cells (CNGCs) were embedded in Epon for ultrastructural investigation, or wholemounts were stained with antibodies against nitric oxide synthase (NOS), vasoactive intestinal polypeptide (VIP), vesicular acetylcholine transporter, neuropeptide Y (NPY), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), substance P (SP), and synaptophysin. In addition, wholemount preparations of the choroid and of the anterior segment were stained for reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-D). Serial sections through choroid and anterior segment were stained with the prior antibodies listed. RESULTS: In the porcine choroid only CNGCs were present. They stained for brain (b)NOS and VIP and were surrounded by SP and VIP-immunoreactive (IR) nerve terminals. The axonal processes of the CNGCs followed the ciliary nerves to the anterior eye segment, where they formed a nerve fiber plexus that terminated in the trabecular meshwork. None of the axons passed into the sparse NOS-IR nerve fiber plexus surrounding the choroidal vasculature. The CNGCs in the human choroid morphologically resembled those seen in the pig. CONCLUSIONS: The CNGC proportion of choroidal ganglion cells is presumably involved in the intrinsic (peripheral) innervation of the aqueous outflow tissues and of the choroid.

Emmetropization in chicks uses optical vergence and relative distance cues to decode defocus.

When visual information is confined to one object plane, the emmetropization end-point is adjusted in accord with the corresponding incident optical vergence at the eye [Proceedings of the 7th International Conference on Myopia (2000) 113]. We now report the effect of adding extra visual information beyond the target plane. Visual conditions were controlled using a cone-lens system: black Maltese cross targets on white opaque backgrounds (OMX) were attached to the open faces of 2.5 cm translucent cones fitted with either 0, +25 or +40 D imaging lenses. An alternative target (TMX) was made by substituting the opaque target background for a transparent background, which allowed access to visual information beyond the target plane. The imaging devices were applied to 7-day-old chicks and worn for 4 days. Prior to this treatment, on day 2, some chicks underwent ciliary nerve section (CNS) to preclude accommodation. All treatments were monocular. Refractive errors and axial ocular dimensions were measured using retinoscopy and A-scan ultrasonography under halothane anesthesia. Treatment effects were specified as mean ( +/-S.D.) interocular differences. Eyes with the OMX/+40 D lens combination remained emmetropic (+0.73 +/-3.57 D), consistent with the target plane being approximately conjugate with the retina. Switching to the TMX caused a hyperopic shift in refractive error (+3.78 +/-3.41 D). This relative shift towards hyperopia in switching from the OMX to the TMX target also occurred for the other two lens powers. Thus, the OMX/+25 D lens induced myopia (-7.00 +/-5.88 D), corresponding to the imposed hyperopic defocus (target plane now imaged behind the retina), and switching to the TMX resulted in a reduction in myopia (-1.73 +/-5.36 D). The OMX/0 D lens combination produced the largest myopic shift, and here, switching to the TMX condition almost eliminated the myopic response (-15.50 +/-6.62 D cf. -0.56 +/-1.24 D). This relative hyperopic shift associated with switching from the OMX to the TMX target was eliminated by CNS surgery. Thus, the two CNS/TMX groups were both more myopic than the equivalent no CNS/TMX groups (+40 D lens: -2.66 +/-2.34 D; +25 D lens: -7.97 +/-6.87 D). When the visual information is restricted to one plane, incident optical vergence appears to direct emmetropization. Adding visual information at other distances produces a shift in the end-point of emmetropization in the direction of the added information. That these effects are dependent on the integrity of the accommodation system implies that accommodation plays a role in emmetropization and represents the first reported evidence of this kind.

Tumours may be innervated.

It is generally assumed that tumours are not innervated. However, following an accidental observation of a nerve fibre within an adenoma of the ciliary body epithelium of the eye, we have further examined two such tumours. One pigmented and one non-pigmented adenoma of the ciliary body epithelium (APCE and ANCE, respectively) that had been surgically removed from two human eyes were processed for ultrastructural evaluation and systematically screened and analysed for the occurrence of nerve tissue under a transmission electron microscope. The adenomas were composed of epithelial tumour cell strands and interposed vascularised connective tissue. Both tumours contained a small number of fine unmyelinated nerve fibres containing clear and dense core vesicles. In both adenomas, the nerve fibres were located in the tumour periphery close to blood vessels and tumour cells. In the APCE, they were also seen in more central areas. Since nerves always have a function, this finding, if confirmed in other neoplasms, may influence our understanding of such innervated tumours.

Expression and channel properties of alpha-bungarotoxin-sensitive acetylcholine receptors on chick ciliary and choroid neurons.

Cell-specific expression of nicotinic acetylcholine receptors (AChRs) was examined using ciliary and choroid neurons isolated from chick ciliary ganglia. At embryonic days 13 and 14 (E13,14) the neurons can be distinguished by size, with ciliary neuron soma diameters exceeding those of choroid neurons by about twofold. Both neuronal populations are known to express two major AChR types: alpha3*-AChRs recognized by mAb35, that contain alpha3, alpha5, beta4, and occasionally beta2 subunits, and alpha-bungarotoxin (alphaBgt)-AChRs recognized and blocked by alphaBgt, that contain alpha7 subunits. We found that maximal whole cell current densities (I/C(m)) mediated by alphaBgt-AChRs were threefold larger for choroid compared with ciliary neurons, while alpha3*-AChR current densities were similar in the two populations. Different densities of total cell-surface alphaBgt-AChRs could not explain the distinct alphaBgt-AChR response densities associated with ciliary and choroid neurons. Ciliary ganglion neurons display abundant [(125)I]-alphaBgt binding ( approximately 10(6) sites/neuron), but digital fluorescence measurements revealed equivalent site densities on both populations. AChR channel classes having single-channel conductances of approximately 30, 40, 60, and 80 pS were present in patches excised from both ciliary and choroid neurons. Treating the neurons with alphaBgt selectively abolished the 60- and 80-pS events, identifying them as arising from alphaBgt-AChRs. Kinetic measurements revealed brief open and long closed durations for alphaBgt-AChR channel currents, predicting a very low probability of being open (p(o)) when compared with 30- or 40-pS alpha3*-AChR channels. None of the channel parameters associated with the 60- and 80-pS alphaBgt-AChRs differed detectably, however, between choroid and ciliary neurons. Instead calculations based on the combined whole cell and single-channel results indicate that choroid neurons express approximately threefold larger numbers of functional alphaBgt-AChRs (N(F)) per unit area than do ciliary neurons. Comparison with total surface [(125)I]-alphaBgt-AChR sites (N(T)), reveals that N(F)/N(T) << 1 for both neuron populations, suggesting that "silent" alphaBgt-AChRs predominate. Choroid neurons may therefore express a higher density of functional alphaBgt-AChRs by recruiting a larger fraction of receptors from the silent pool than do ciliary neurons.

Modulation of constant light effects on the eye by ciliary ganglionectomy and optic nerve section.

Our previous studies have shown that an environment of constant light (CL) can lead to development of high degree of hyperopia in newborn chicks by inducing severe corneal flattening, and compensatory growth of the vitreous chamber. We wish to know whether the abnormal eye growth and progressive hyperopia under CL conditions is accomplished by a mechanism that uses the visual processing pathways of the central nervous system (CNS) or by a mechanism located in the eye. Thirty white leghorn chicks (Cornell K-strain) were raised under 12 h light/12 h dark (12L/12D) for either optic nerve section (ONS) or ciliary ganglion section (CGS). Another 30 chicks were raised under CL for ONS or CGS. Refractive states and corneal curvatures were measured by infrared (IR) photoretinoscopy and IR keratometry, respectively. The axial lengths of the ocular components were measured by A-scan ultrasonography. Both ONS and CGS surgery produced dilated pupils and accommodative paralysis. Four weeks after surgery, CGS eyes exhibited a hyperopic defocus, flatter cornea, and shorter vitreous chamber depth under both CL and normal conditions, whereas ONS eyes showed a smaller radius of corneal curvature and shallow vitreous chamber only in the normal light cycle group. CGS eyes of CL chicks showed significantly deeper vitreous chambers than did fellow control eyes. Our results indicate that optic nerve section does not seem to influence CL effects. Thus, local mechanisms may play a major role in the ocular development of chicks. The ciliary nerve is necessary for the normal corneal and anterior chamber growth, and prevents CL effects. The progressively increasing vitreous chamber depth under CL may be influenced by both local and central mechanisms.

Intraocular pressure lowering by S-allylmercaptocysteine in rabbits.

The purpose of this study was to examine the actions of a garlic-derived compound, S-allylmercaptocysteine (SAMC) on intraocular pressure (IOP) and to determine the possible involvement of sulfhydryl reactivity, sympathetic neuronal activity and atrial natriuretic peptide (ANP) in the IOP response. Topical, unilateral application of SAMC (20, 100, 200 microg) elicited dose-dependent decreases in IOP. The magnitude of the IOP-lowering effect induced by SAMC was between four to six mmHg. The ocular hypotensive responses were unilateral, peaked at one to three hours and lasted from two to four hours. The IOP-lowering effect by SAMC (100 microg) was enhanced modestly by topical, bilateral pretreatment with a reducing agent, tris(2-carboxyethyl) phosphine (100 microg) which itself produced no change in IOP. No alteration of pupil diameter was observed following topical application of either SAMC or tris(2-carboxyethyl) phosphine. Thus, alteration of sulfhydryl reactivity does not seem to be a major mechanism of action for SAMC. SAMC caused no change of basal and electrically stimulated norepinephrine release in rabbit iris-ciliary bodies, ruling out a prejunctional effect on sympathetic nerve activity. However, SAMC increased the ANP levels in aqueous humor by five-fold. It is concluded that the ocular hypotensive response induced by SAMC in rabbits could involve the elevation of ANP levels in aqueous humor.

Calcium transients evoked by action potentials in the somata of chick ciliary neurons.

The effect of action potentials on the calcium concentration in the somata of chick ciliary neurons ([Ca2+]s) was determined by loading these with the calcium indicator calcium green-1. Following trains of 1-10 impulses (30 Hz) to the postganglionic nerve, the [Ca2+]s increased rapidly and then declined along a single exponential with a time constant of 0.70 +/- 0.04 s (fast phase). After trains of 20 or 50 impulses, the elevated [Ca2+]s declined as the sum of two exponentials, with time constants of 0.78 +/- 0.12 s (fast phase) and 4.0 +/- 0.4 s (moderate phase). After a 600-impulse postganglionic train of impulses, the elevated [Ca2+]s declined quickly over about 1 s, and then as the sum of two exponentials: that of the moderate phase and a slower component with a time constant of 109 +/- 16 s (slow phase). Similar time courses were observed following stimuli to the preganglionic nerve. Caffeine (3 mM) and ryanodine (20 microM) both sped the fast phase and slowed the moderate phase of [Ca2+]s decline. Carbonyl cyanide m-chlorophenyl hydrazone (CCCP, 2 microM) slowed the slow phase, without affecting the other phases of decline. These results are discussed in relation to identifying the mechanisms responsible for these different phases of Ca2+ removal.

Calpain inhibitors, but not caspase inhibitors, prevent actin proteolysis and DNA fragmentation during apoptosis.

Apoptosis, or programmed cell death, involves a cascade of regulatory events leading to the activation of specific proteases. However, the key substrates for these proteases remain to be identified. We previously demonstrated that levels of five unidentified polypeptides were specifically increased in neurons from embryonic chicken ciliary ganglia undergoing apoptosis by trophic deprivation. Here we show by microsequencing of two of these polypeptides that they are fragments of actin. One of them represents cleavage of actin at the site of interaction with DNase I. The same actin fragments are also found at early stages of apoptosis in chicken and rat dorsal root ganglion neurons, chicken spinal motoneurons and rat thymocytes. Actin fragmentation may play a role in the apoptotic process, since calpain inhibitors I and II both inhibit neuronal death and suppress actin fragmentation. In contrast, caspase (ICE family) inhibitors, though effective in delaying neuronal death, do not prevent actin cleavage or DNA fragmentation. These results indicate a key role for calpain-like proteases in neuronal programmed cell death and suggest that actin fragmentation in the cell is correlated with subsequent DNA fragmentation.

Neuropeptide Y-like immunoreactivity localizes to preganglionic axon terminals in the rhesus monkey ciliary ganglion.

PURPOSE: To characterize neuropeptide distribution in the ciliary ganglion of rhesus monkeys (Macaca mulatta). METHODS: Cryostat tissue sections of fixed rhesus monkey ciliary, pterygopalatine, superior cervical, and trigeminal ganglia were incubated with antisera to neuropeptide Y (NPY), calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), tyrosine hydroxylase (TH), and dopamine-beta-hydroxylase (DBH). Antibody binding was visualized by indirect immunofluorescence. RESULTS: NPY-like immunoreactive (LI) nerve terminals surrounded 80% of ciliary ganglion cells, but ciliary ganglion cell somata were unstained. NPY-LI cells were present in the superior cervical ganglion, in which almost all cells were TH- and DBH-LI, and in the pterygopalatine ganglion, in which almost all cells were VIP-LI. Because neither TH, DBH, nor VIP immunoreactivity was detected in nerves contacting ciliary ganglion cells, the NPY-LI input to ciliary neurons does not likely derive from the autonomic ganglia. The trigeminal ganglion, another potential source, had no NPY-LI neurons. CGRP- and SP-LI axons from the nasociliary nerve traversed the ciliary ganglion; a small number of varicose axons were distributed among ganglion cells and rarely surrounded cell somata. Most ciliary ganglion cells were TH-LI, but only a few were DBH-LI. CONCLUSIONS: Based on these patterns of peptide immunoreactivities, the NPY-LI nerve fibers investing ciliary ganglion cells in the rhesus monkey are most likely preganglionic axon terminals of mesencephalic parasympathetic neurons. Although the origin and function of these NPY-LI nerves remains to be established, the present finding adds to the remarkable diversity of neuropeptide immunoreactivity so far identified in preganglionic and postganglionic cells of the ciliary ganglion in different species of birds and mammals, including primates.

Natural and imposed astigmatism and their relation to emmetropization in the chick.

This study investigated the ocular response of young chicks to astigmatic errors imposed by spectacle lenses and as a related issue, we examined the nature and prevalence of astigmatism in young chicks, and its relation to corneal development and natural emmetropization. Normal hatchling chicks exhibited significant against-the-rule refractive astigmatism (approx. 8 D) of which 60-90% was corneal. Both types of astigmatism decreased in magnitude with normal corneal development as part of emmetropization. The apparent association with corneal growth is consistent with two further observations: (1) that smaller corneas, induced by constant light rearing, had higher than normal astigmatism (1.5 D greater at 15 days), (ii) that enlarged corneas, due to form deprivation, had reduced astigmatism (2.4 D less). When astigmatism was artificially imposed with (+/-10 DC spectacle lenses), altered ocular growth patterns were observed, although the changes were not consistent with the chicks having emmetropized to the imposed astigmatism. Irrespective of the axis setting used in positioning the lenses (45 degrees, 90 degrees, 180 degrees), eyes became hyperopic with +10 DC lenses (+8.8 +/- 1.3 D), and became slightly myopic with 10 DC lenses (-1.8 +/- 1.9 D). These refractive changes are consistent with the chicks having emmetropized to the more myopic meridian rather than the equivalent mean spherical error imposed (responses of control groups to +5 D and -5 D spherical lenses were +5.2 +/- 1.0 D and -5.1 +/- 0.8 D resp.). The same was true for chicks first prevented from accommodating by prior ciliary nerve section, except for one group wearing the 10 DC lens at 45 degrees axis where astigmatic changes consistent with partial compensation were seen, although this may represent an artefact of the surgery. These results argue against 'astigmatic emmetropization' as a normal phenomenon. Also consistent with this finding was the lack of significant astigmatic changes with accommodation-stimulating and inhibiting drugs (nicotine and vercuronium resp.), for normal chicks. These results imply that accommodation, while the most likely mechanism for astigmatic emmetropization, has little capacity to compensate for imposed astigmatic focussing errors.

Response to prejunctional adenosine receptors is dependent on stimulus frequency.

PURPOSE: To characterize the adenosine receptor modulation of norepinephrine (NE) release from sympathetic neurons in the isolated rabbit iris/ciliary body. METHODS: Iris/ciliary bodies were isolated from New Zealand White rabbits and incubated in the presence of 3H-NE. Norepinephrine release was elicited by field stimulation with varied frequencies from 5 to 30 Hz. The effects of adenosinergic and alpha 2 adrenergic compounds on NE release were determined and compared. RESULTS: At a stimulation frequency of 5 Hz, the addition of the adenosine A1 agonist CHA did not significantly alter 3H-NE release. However, in the presence of the alpha 2 adrenergic antagonist yohimbine, the addition of CHA produced a dose-related reduction in 3H-NE release. The EC50 for this reduction was 14 nM. At a stimulus frequency of 20 Hz, the addition of CHA alone (10(-6) M) produced a significant reduction in 3H-NE release of 41%. The EC50s for the adenosine A1 agonists CHA- and R-PIA-induced suppression of 3H-NE release at 20 Hz were 32 and 24 nM, respectively. The adenosine A2 agonist CV-1808 did not alter 3H-NE release at stimulation frequencies of 5 or 20 Hz. Pretreatment of tissues with the adenosine A1 antagonist CPT or pertussis toxin reversed the suppression of 3H-NE release induced by CHA. Comparison of the inhibitory responses of CHA to the alpha 2 adrenergic agonist UK-14,304 at stimulus frequencies of 5 to 30 Hz demonstrated that this adenosine A1 agonist was effective only in suppressing NE release at frequencies of 20 Hz or greater. In contrast, the alpha 2 adrenergic agonist UK-14,304 was most effective in reducing NE release at 5 Hz. CONCLUSIONS: These results provide evidence that adenosine agonists inhibit 3H-NE release in the iris/ciliary body via prejunctional adenosine A1 receptors linked to Gi/o-protein. However, the expression of this response was dependent on the frequency of neuronal stimulation. Hence, prejunctional adenosine A1 receptors may act to selectively limit high-frequency neurotransmission.