Enkephalin immunoreactivity in iris nerves: Distribution in normal and grafted irides,persistence and enhanced fluorescence after denervations

Summary The morphology and distribution of nerve fibers showing enkephalin-like immunoreactivity was studied in rat and mouse iris whole mounts. In adult rat, a relatively dense network of varicose fibers was seen throughout the iris. Individual, long, usually smooth fibers were observed running together with non-fluorescent fibers in bundles. Positive nerve fibers were also seen in the ciliary body and the choroid membrane. The fluorescence intensity was normally low. No enkephalin-positive fibers were detected in adult mouse iris.Extirpation or lesioning either one or all the three ganglia known to supply the rat iris with nerve fibers, the superior cervical, the ciliary and the trigeminal ganglia, caused no detectable decrease in amount of enkephalin-positive fibers. However, in irides grafted to the anterior eye chamber of adult recipients, no enkephalin-positive fibers could be observed 2–12 days postoperatively, strongly suggesting that degeneration of these fibers had occurred. When iris grafts were left longer in the eye, nerve fibers with enkephalin-like immunoreactivity reappeared. An increased fluorescence intensity was observed both in the ipsilateral and contralateral iris following extirpation or lesioning all three ganglia and in the ipsilateral iris after extirpation of the ciliary ganglion. Three days after a systemic injection of capsaicin, which causes a permanent disappearance of substance P fibers, the same phenomenon was often observed. This raises the possibility of an interaction between the enkephalin-positive and the substance P fiber systems in the iris.The present experiments thus demonstrate a rich network of enkephalin immunoreactive nerve fibers in the rat iris originating outside the iris but apparently not in the ciliary, trigeminal or superior cervical ganglion.     

Enkephalin-like immunofluorescence in nerves of the rat iris following systemic capsaicin injection

A network of nerve fibers with an enkephalin-like immunoreactivity was demonstrated in rat iris whole mounts. Systemic administration of capsaicin in doses which caused partial (5 mg/kg) or complete (50 mg/kg) disappearance of substance P-containing fibers in the iris did not cause degeneration of enkephalin-positive nerve fibers. The enkephalin-immunoreactive network seemed intact also after a capsaicin dose of 250 mg/kg. In fact, the fluorescence intensity of the nerve fibers showing enkephalin-immunoreactivity was often increased three days after a capsaicin injection in a dose of 50 mg/kg. The mechanism behind this effect of capsaicin remains to be elucidated, but could be due either to a direct effect on the enkephalin-positive nerves or involve the disappearance of substance P nerves and/or a simultaneous inflammatory response. However, an increased fluorescence intensity of the enkephalin-immunoreactive fibers was sometimes seen also without capsaicin treatment.     

Galanin-immunoreactive nerves in the rat iris: alterations induced by denervations

Summary The iris and choroid membrane of the adult rat contain nerve fibers expressing immunoreactivity to the neuropeptide galanin. The density and distribution of galanin-positive nerve fibers varied from iris to iris and, particularly, among animals. Smooth, non-terminal axons were seen running in nerve bundles consisting of otherwise negative fibers. From the choroid membrane these bundles reached the iris via the ciliary body. Axons were frequently seen to branch giving rise to a sparse system of varicose, single fibers in the dilator plate and sphincter area. Galanin-positive fibers were sometimes also seen outlining blood vessels.Capsaicin, in a dose that causes permanent depletion of substance P- and cholecystokinin-immunoreactive fibers in the iris, caused no change in amount of galanin-positive fibers. Removal of the superior cervical ganglion caused a rapid and pronounced increase in the number of galanin-immunoreactive nerve fibers. Similarly, removal of the ciliary ganglion appeared to increase galanin immunoreactivity, while removal of the pterygopalatine ganglion was less effective. Lesioning of the trigeminal ganglion caused a disappearance of galanin immunoreactivity. The sympathetectomy-induced increase was counteracted by capsaicin.Galanin-positive nerve cell bodies were present in both the superior cervical and the trigeminal ganglia. In the superior cervical ganglion, immunoreactive galanin did not seem to coexist with neuropeptide Y-positive cells; in the trigeminal ganglion, some galanin-positive cells also contained calcitonin gene-related peptide (CGRP) immunoreactivity, while most cells did not. In the iris, double-staining suggested that CGRP and galanin immunoreactivities were contained in different fiber populations.We conclude that the rat iris and choroid membrane contain a sparse plexus of nerve fibers expressing galanin-like immunoreactivity. It is suggested that these fibers are derived from the trigeminal ganglion. The iris is able to respond with a pronounced increase in number of galanin-immunoreactive nerve fibers to certain denervation procedures.     

Neurofilament-like and glial fibrillary acidic protein-like immunoreactivities in rat and guinea-pig sympathetic ganglia in situ and after perturbation

Summary The presence of neurofilament (NF)-like and glial fibrillary acidic protein (GFAP)-like immunoreactivities was studied in sympathetic ganglia of adult rats and guinea pigs during normal conditions and after perturbation. In the superior cervical ganglion (SCG) of normal rats, many ganglion cells and nerve fibers show NF immunoreactivity. Some of these nerve fibers disappear after preganglionic decentralization of SCG; this indicates the presence of a mixture of preand postganglionic NF-positive nerves in the ganglion. Cuts in both preand postganglionic nerves result in a marked increase in GFAP immunoreactivity in SCG, whereas NF immunoreactivity increases in nerve cell bodies after preganglionic cuts. Only a few ganglion cells show NF immunoreactivity in the normal SCG of guinea pig. All intraganglionic NF-positive nerves are of preganglionic origin; decentralization abolishes NF immunoreactivity in these nerve fibers. The inferior mesenteric ganglion, the hypogastric nerves and colonic nerves in guinea pigs contain large numbers of strongly NF-immunoreactive nerve fibers.When the SCG of adult rat is grafted to the anterior eye chamber of adult rat recipients, both ganglionic cell bodies and nerve fibers, forming on the host iris from the grafted ganglion, are NF-positive. As only the perikarya of these neurons normally exhibit NF immunoreactivity, and the terminal iris arborizations are NF-negative, it appears that the grafting procedure causes NF immunoreactivity to become more widespread in growing SCG neurons.     

On the origin and distribution of vasoactive intestinal polypeptide-, peptide HI-, and cholecystokinin-like-immunoreactive nerve fibers in the rat iris

Summary The presence and distribution of nerve fibers expressing immunoreactivity to the neuropeptides vasoactive intestinal polypeptide, peptide HI and cholecystokinin was examined in stretch-prepared rat iris whole mounts. By use of antiserum to vasoactive intestinal polypeptide an irregular, relatively sparse network of varicose, intensely fluorescent fibers was observed innervating both the dilator plate and the sphincter area. Positive fibers were present also in the ciliary body and the choroid membrane. Surprisingly, a large variation in the amount of vasoactive intestinal polypeptide-positive nerves was seen among irides. Furthermore, an uneven distribution of fluorescent nerve fibers was observed within individual irides. Thus, some areas had a relatively dense innervation, whereas others were devoid of immunoreactive nerve fibers. A similar fiber system was detected using antiserum to peptide HI. In all probability, vasoactive intestinal polypeptide and peptide HI coexist within the same nerve population. A denser and more regular network of cholecystokinin-positive fibers was found in normal rat irides. Such fibers were also present in the sphincter area and in high density in the choroid membrane. Neither extirpation of the superior cervical nor the ciliary ganglion caused any detectable decrease in amount of either vasoactive intestinal polypeptide/peptide HI- or cholecystokinin-positive fibers. However, capsaicin, which in the iris causes permanent disappearance of substance-P fibers, had a similar effect on cholecystokinin-positive fibers, whereas no effect was noted on the vasoactive intestinal polypeptide/peptide HI fiber network. It is concluded that the rat iris contains a network of vasoactive intestinal polypeptide/peptide HI-positive nerves that does not originate in either the superior cervical or the ciliary ganglion, and most probably also not in the trigeminal ganglion, and a cholecystokinin-positive network that probably originates in the trigeminal ganglion.     

GE-25-like immunoreactivity in the rat eye

This study aimed to investigate the presence and distribution of the chromogranin A-derived peptide GE-25 in the rat eye. The molecular form detected by the GE-25 antiserum was evaluated in the rat trigeminal ganglion, retina and remaining tissues of the rat eye by means of Western blots and the distribution pattern of GE-25-like immunoreactivity was studied in the rat eye and rat trigeminal ganglion by immunofluorescence. One single band of approximately 70kDa was stained in the trigeminal ganglion and retina which represents the uncleaved intact chromogranin A indicating that the proteolytic processing of chromogranin A to GE-25 is limited in these tissues. Sparse GE-25-like immunoreactive nerve fibers were visualized in the corneal stroma, at the limbus around blood vessels, in the sphincter and dilator muscle and stroma of the iris, in the stroma of the ciliary body and ciliary processes and in the stroma and around blood vessels in the choroid. This distribution pattern is characteristic for neuropeptides whereas the presence of immunoreactivity in the corneal endothelium and in Müller glia in the retina is atypical. GE-25-like immunoreactivity was found in small to medium-sized ganglion cells in the rat trigeminal ganglion clearly indicating that the nerve fibers in the rat eye are of sensory origin. The colocalization of GE-25-immunoreactivity with SP-immunoreactivity in the rat ciliary body is in agreement with the presumption of the sensory nature of the innervation of the anterior segment of the eye by GE-25.     

Distribution of Thy-1-like immunoreactivity in normal, sympathetically denervated and grafted mouse irides

The distribution of Thy-1-like immunoreactivity was studied in whole-mounts of adult mouse iris and intraocular iris grafts 4 days and 4 weeks postoperatively. After fixation in picric acid/paraformaldehyde, the irides were incubated with a polyclonal rabbit anti-mouse brain Thy-1 antibody. In the adult mouse iris, a dense network of thin bundles and individual fibres was seen on the dilator plate and in the sphincter. Fluorescence paucities, resembling Schwann cell nuclei, were frequently seen along the bundles. Numerous mast cells, stained specifically with the Thy-1 antibody, were scattered over the entire surface of the iris. The ciliary body contained several brightly fluorescent bundles, and some circularly running individual fibres. In 4-day iris grafts, the Thy-1-like immunoreactivity had disappeared, except in mast cells. After 4 weeks in oculo, a regular plexus of thin fibres had reappeared in the iris grafts. Sympathetic denervation of adult irides did not seem to affect the Thy-1 immunoreactivity in terms of either fluorescence intensity or fibre distribution. The present data suggest a distribution of the glycoprotein Thy-1 along nerve fibres in the iris.     

Distribution of Thy-1-like immunoreactivity in normal,sympathetically denervated and grafted mouse irides

Summary The distribution of Thy-1-like immunoreactivity was studied in whole-mounts of adult mouse iris and intraocular iris grafts 4 days and 4 weeks postoperatively. After fixation in picric acid/paraformaldehyde, the irides were incubated with a polyclonal rabbit anti-mouse brain Thy-1 antibody. In the adult mouse iris, a dense network of thin bundles and individual fibres was seen on the dilator plate and in the sphincter. Fluorescence paucities, resembling Schwann cell nuclei, were frequently seen along the bundles. Numerous mast cells, stained specifically with the Thy-1 antibody, were scattered over the entire surface of the iris. The ciliary body contained several brightly fluorescent bundles, and some circularly running individual fibres. In 4-day iris grafts, the Thy-1-like immunoreactivity had disappeared, except in mast cells. After 4 weeks in oculo, a regular plexus of thin fibres had reappeared in the iris grafts. Sympathetic denervation of adult irides did not seem to affect the Thy-1 immunoreactivity in terms of either fluorescence intensity or fibre distribution. The present data suggest a distribution of the glycoprotein Thy-1 along nerve fibres in the iris.     

Target-specific innervation by autonomic and sensory nerve fibers in hairy fetal skin transplanted into the anterior eye chamber of adult rat

Summary Pieces of hairy skin tissue of fetal rat were transplanted into the anterior eye chamber of adult rats. The ability of autonomic and sensory nerve fibers from the host iris to innervate the grafted skin tissue was immunohistochemically and enzyme-histochemically examined using antisera against tyrosine hydroxylase (TH), substance P (SP), calcitonin gene-related peptide (CGRP) and vasoactive intestinal peptide (VIP), and a reaction medium for acetylcholinesterase (AchE). The grafted tissue was successfully implanted and connected with the host iris. Epidermis, dermis, subcutaneous tissue, hairs, hair follicles, sebaceous glands, and piloerector muscles developed in the graft. Two weeks after transplantation, TH-, SP-, and CGRP-immunoreactive fibers were observed in association with the blood vessels in the graft. Four weeks after transplantation, TH-immunoreactive fibers were distributed in the piloerector muscles, whereas SP-and CGRP-immunoreactive fibers were present around the hair follicles. VIP-immunoreactive and AchE-positive fibers were restricted to the host iris at all survival times. These results suggest that the outgrowth of autonomic and sensory nerve fibers from the host iris show target specificity for the grafted skin tissue.     

PE-11, a peptide derived from chromogranin B, in the rat eye

The aim of the study was to investigate the presence and distribution of PE-11, a peptide derived from chromogranin B, in the rat eye. For this purpose, newborn rats were injected with a single dosage of 50 mg/kg capsaicin subcutaneously under the neck fold and after three months, particular eye tissues were dissected and the concentration of PE-11-like immunoreactivity was determined by radioimmunoassay. Furthermore, PE-11-like immunoreactivities were characterized in an extract of the rat eye by reversed phase HPLC. Then, the distribution pattern of PE-11 was investigated in the rat eye and rat trigeminal ganglion by immunofluorescence. As a result, PE-11 was present in each tissue of the rat eye and capsaicin pretreatment led to a 88.05% (±7.07) and a 64.26% (±14.17) decrease of the levels of PE-11 in the cornea and choroid/sclera, respectively, and to a complete loss in the iris/ciliary body complex. Approximately 70% of immunoreactivities detected by the PE-11 antiserum have been found to represent authentic PE-11. Sparse nerve fibers were visualized in the corneal and uveal stroma, surrounding blood vessels at the limbus, ciliary body and choroid and in association with the dilator and sphincter muscle. Furthermore, immunoreactivity was present in the corneal endothelium. In the retina and optic nerve, glia was labeled. In the rat trigeminal ganglion, PE-11-immunoreactivity was visualized in small and medium sized ganglion cells with a diameter of up to 30 μm. In conclusion, there is unequivocal evidence that PE-11 is a constituent of capsaicin-sensitive sensory neurons innervating the rat eye and the distribution pattern is typically peptidergic in the peripheral innervation but in the retina completely atypical for neuropeptides and unique.     

Immunoreactivity for substance P in the gasserian ganglion, ophthalmic nerve and anterior segment of the rabbit eye

Summary The distribution of substance P (SP) immunofluorescence was investigated in the Gasserian ganglion, ophthalmic nerve and in the anterior segment of the rabbit eye. About one third of the nerve cell bodies in the Gasserian ganglion exhibited SP immunofluorescence, which was also observed in some nerve fibres of the ophthalmic nerve. In the cornea, some SP-positive iris contained numerous nerve fibres with SP immunofluorescence. In the sphincter area such fibres were circular, while the orientation of the SP fibres was radial in the dilator muscle. Both in the iris and in the ciliary body, the largest vessels were surrounded by nerves exhibiting SP immunofluorescence. A few nerve fibres also appeared in the stroma of the ciliary processes.     

Presence and actions of vasopressin-like peptides in the rabbit anterior uvea

The presence of vasopressin-like immunoreactivity (VP-IR) in the rabbit eye was demonstrated by radioimmunoassay. Trigeminal nerve denervation resulted in a significant and selective decrease in the levels of VP-IR in the iris sphincter muscle and the cornea. The isolated iris sphincter muscle contracted in response to low concentrations of [Arg8]vasopressin (AVP) and related peptides. The V1 vasopressin receptor antagonist, d(CH2)5Tyr(Me)AVP, potently inhibited the contractile responses to AVP. AVP was found to induce an increase in the accumulation of inositol phosphates in the iris sphincter muscle but not in the dilator/ciliary body preparation in vitro. The present investigation demonstrates the presence of VP-IR in the rabbit eye and that this substance may be another sensory nerve-derived mediator acting on specific target sites in the anterior uvea.     

Formation of calyx-like contacts preferentially on appropriate target neurons in culture

The availability of culture systems for both Edinger Westphal and ciliary ganglion neurons has made it possible to examine the interactions in culture between two populations of vertebrate neurons that synapse in vivo. In the chick, Edinger Westphal neurons provide the sole presynaptic input to the ciliary ganglion and, through this projection, are responsible for the control of lens curvature (accommodation), iris constriction, and possibly smooth muscle function in the choroid layer of the eye. When embryonic chick Edinger Westphal and ciliary ganglion neurons were combined in culture and stained for enkephalin-like immunoreactivity to visualize Edinger Westphal terminals, stained calyx-like contacts were observed that resemble the calyciform terminals formed between Edinger Westphal processes and ciliary neurons in the ciliary ganglion in vivo. Although stained calyx-like contacts could also be found in Edinger Westphal-alone and ciliary ganglion-alone cultures, many more were observed when the two cell types were cultured together. The increase depended specifically on the ciliary ganglion neurons since substitution of either dorsal root ganglion or sympathetic ganglion neurons for them in the cocultures did not increase the number of calyx-like contacts staining positive for enkephalin over those present in cultures of Edinger Westphal neurons alone. When Edinger Westphal neurons were grown simultaneously with dorsal root and ciliary ganglion neurons, calyx-like contacts with enkephalin-like immunoreactivity were found to terminate preferentially on the latter. These findings suggest that vertebrate neurons can form morphologically specific contacts preferentially on appropriate target cells in culture in the absence of many of the potential cues present in the intact tissue.     

Axonal tracing of autonomic nerve fibers to the superficial temporal artery in the rat

Summary The origin of nerve fibers to the superficial temporal artery of the rat was studied by retrograde tracing with the fluorescent dye True Blue (TB). Application of TB to the rat superficial temporal artery labeled perikarya in the superior cervical ganglion, the otic ganglion, the sphenopalatine ganglion, the jugular-nodose ganglionic complex, and the trigeminal ganglion. The labeled perikarya were located in ipsilateral ganglia; a few neuronal somata were, in addition, seen in contralateral ganglia. Judging from the number of labeled nerve cell bodies the majority of fibers contributing to the perivascular innervation originate from the superior cervical, sphenopalatine and trigeminal ganglia. A moderate labeling was seen in the otic ganglion, whereas only few perikarya were labeled in the jugular-nodose ganglionic complex. Furthermore, TB-labeled perikarya were examined for the presence of neuropeptides. In the superior cervical ganglion, all TB-labeled nerve cell bodies contained neuropeptide Y. In the sphenopalatine and otic ganglia, the majority of the labeled perikarya were endowed with vasoactive intestinal polypeptide. In the trigeminal ganglion, the majority of the TB-labeled nerve cell bodies displayed calcitonin gene-related peptide, while a small population of the TB-labeled neuronal elements contained, in addition, substance P. In conclusion, these findings indicate that the majority of peptide-containing nerve fibers to the superficial temporal artery originate in ipsilateral cranial ganglia; a few fibers, however, may originate in contralateral ganglia.     

Calcitonin gene-related peptide in the eye: release by sensory nerve stimulation and effects associated with neurogenic inflammation

Calcitonin gene-related peptide (CGRP) in the anterior uvea coexists with tachykinins (substance P and neurokinin A) in sensory nerve fibers deriving from the trigeminal ganglion. Mechanical or electrical stimulation of the intracranial part of the trigeminal nerve/ganglion in rabbits produced a marked hyperemia in the anterior segment of the eye, increased intraocular pressure, breakdown of the blood-aqueous barrier and miosis. Simultaneously, CGRP-like immunoreactivity was released into the aqueous humor. This suggests that the highly vasoactive CGRP can be released from sensory nerve fibers to participate in vascular responses. Unlike the tachykinins, CGRP per se was without effect on the pupillary diameter while disrupting the blood-aqueous barrier (resulting in aqueous flare) upon intravitreal injection. In addition, CGRP enhanced the aqueous flare evoked by a minimal eye trauma (infrared irradiation of the iris). The miosis evoked by the intravitreal injection of substance P was more pronounced when CGRP was injected simultaneously, and finally, substance P induced aqueous flare much more effectively when given together with a threshold dose of CGRP.     

Absence of the alpha and gamma subunits of 7S nerve growth factor in denervated rodent iris: immunocytochemical studies

Immunocytochemical studies were performed to determine if denervated rodent iris produces nerve growth factor (NGF) in a form chemically similar to that of the 7S NGF complex in mouse submandibular glands. Antisera to the alpha, beta, and gamma subunits of 7S NGF were raised in rabbits and characterized on immunoblots of SDS-containing polyacrylamide gels. Antisera were applied to stretch preparations of rat and mouse irides that were cultured for periods of 2 to 6 days or sympathetically denervated by superior cervical ganglionectomy and left in situ 4 days. Antibody binding was visualized by indirect immunofluorescence. In control studies done on plastic sections of mouse submandibular glands, antisera co-localized the three subunits of 7S NGF within secretory granules of granular tubule cells. In denervated rat iris, beta NGF immunoreactivity was evident in a cellular plexus that resembled in distribution and morphology nerve fibers in the normal iris, in agreement with a previous study (R.A. Rush (1984). Nature (London) 312, 364-367). Identical staining patterns were observed in mouse iris. In neither rat or mouse, however, did the nerve-like processes stain with antibodies suggests that the NGF-like protein in denervated rodent iris is not synthesized as part of the 7S NGF complex. Iris also did not react with antibodies to epidermal growth factor, a protein co-localized with NGF in mouse submandibular glands and in guinea pig prostate.     

大鼠脊神经节内交感神经支配的荧光组织化学与HRP示踪观察

本研究应用乙醛酸诱发儿茶酚胺（ＣＡ）荧光技术观察大鼠肾上腺素（ＮＡ）能神经在脊神经节内的分布;并应用ＨＲＰ顺、逆行追踪技术对脊神经节内ＮＡ能神经纤维的起源及其与脊神经节神经元的关系进行了探讨。荧光组织化学观察发现、有些神经节神经元胞体周围分布有带膨体的ＮＡ能神经末梢;有的紧密围绕脊神经节细胞——卫星细胞复合体。颈上交感神经节内注射霍乱毒素Ｂ亚单位结合ＨＲＰ（ＣＢ┐ＨＲＰ）,在同侧Ｃ３～６节段脊神经节内可见标记的点状纤维末梢紧邻于节细胞旁。Ｔ１１～Ｌ２节段脊神经节内注射ＨＲＰ后,在同侧椎旁交感链（Ｔ９～Ｌ１）内可见标记的交感节后神经元胞体。上述实验结果表明,交感节后神经元发出节后纤维可直接到达脊神经节内,与节细胞发生接触。本研究提示、交感神经在脊神经节水平可能参与躯体初级传入信息的调制     

Localization of substance P- and enkephalin-like immunoreactivity in the human paravertebral sympathetic ganglia

The presence of substance P- and enkephalin-like immunoreactive nerve fibers and terminals is demonstrated in the human paravertebral sympathetic ganglia by an indirect immunofluorescence technique. Substance P-positive nerve structures appear in the form of fiber bundles, isolated varicose filaments and dot-like and basket-like nerve terminals around the neuronal cell bodies. Their density shows a remarkable individual variability. Enkephalin-positive nerve structures appear as isolated varicose filaments and dot-like nerve terminals, forming densely innervated patchy areas. No substance P- or enkephalin-containing cell bodies were detected. No overlapping seems to exist among the areas innervated by the two types of neuropeptides.     

Galanin-immunoreactive nerves in the female rat paracervical ganglion and uterine cervix: distribution and reaction to capsaicin

Summary The presence and distribution of galanin-immunoreactivity was examined in the uterine cervix and paracervical autonomic ganglia of the female rat. Some animals were treated with capsaicin to determine if galanin-immunoreactivity was present in small-diameter primary afferent nerves. Other animals were treated with the noradrenergic neurotoxin 6-hydroxydopamine to ascertain if galanin-immunoreactivity was present in sympathetic noradrenergic nerves. Galanin-immunoreactive nerve fibers were sparse in the cervical myometrium and vasculature, but numerous in the paracervical ganglion where they appeared to innervate principal neurons. Immunoreactivity was also present in dorsal root ganglia, dorsal horn of spinal cord, and inferior mesenteric ganglia. Capsaicin treatment resulted in a marked reduction of galanin-immunoreactivity in the spinal cord dorsal horn, but not in the dorsal root ganglia, paracervical ganglia, or cervix (although there was a substantial reduction of substance P-, neurokinin A-, and calcitonin gene-related peptide-immunoreactivity in the dorsal horn, dorsal root ganglia, and uterine cervix). 6-Hydroxydopamine treatment did not cause any appreciable change in the galanin-immunoreactivity in any tissues. We conclude that galanin-like immunoreactivity is expressed in nerve fibers innervating the paracervical ganglia and uterine cervix of the female rat. This immunoreactivity is probably present in afferent nerves and could play a role in neuroendocrine reflexes and in reproductive function.     

Postnatal development of autonomic and sensory innervation of thoracic hairy skin in the rat

Summary Histochemical, immunocytochemical, and radioenzymatic techniques were used to examine the neurotransmitter-related properties of the innervation of thoracic hairy skin in rats during adulthood and postnatal development. In the adult, catecholamine-containing fibers were associated with blood vessels and piloerector muscles, and ran in nerve bundles throughout the dermis. The distribution of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers was identical. Neuronal fibers displaying neuropeptide Y (NPY) immunoreactivity were seen in association with blood vessels. Double-labeling studies suggested that most, if not all, NPY-IR fibers were also TH-IR and likewise most, if not all, vessel-associated TH-IR fibers were also NPY-IR. Calcitonin gene-related peptide (CGRP)-IR fibers were observed near and penetrating into the epidermis, in close association with hair follicles and blood vessels, and in nerve bundles. A similar distribution of substance P (SP)-IR fibers was evident. In adult animals treated as neonates with the sympathetic neurotoxin 6-hydroxydopamine, a virtual absence of TH-IR and NPY-IR fibers was observed, whereas the distribution of CGRP-IR and SP-IR fibers appeared unaltered. During postnatal development, a generalized increase in the number, fluorescence intensity, and varicose morphology of neuronal fibers displaying catecholamine fluorescence, NPY-IR, CGRP-IR, and SP-IR was observed. By postnatal day 21, the distribution of the above fibers had reached essentially adult levels, although the density of epidermal-associated CGRP-IR and SP-IR fibers was significantly greater than in the adult. The following were not evident in thoracic hairy skin at any timepoint examined: choline acetyltransferase activity, acetylcholinesterase histochemical staining or immunoreactivity, fibers displaying immunoreactivity to vasoactive intestinal peptide, cholecystokinin, or leucine-enkephalin. The present study demonstrates that the thoracic hairy skin in developing and adult rats receives an abundant sympathetic catecholaminergic and sensory innervation, but not a cholinergic innervation.