Beta-adrenergic and muscarinic receptors of parotid gland following maintenance of rats on liquid diet

Parotid gland of adult rats maintained exclusively on liquid (milk) diet for 7 or 13 days showed a 25% reduction in number of beta-adrenoceptors, and after 21 days, the reduction was 33%; with maintenance of rats on Metrecal for 7 days, the decrease was 24% for female rats and 22% for male rats. The decrease in number of muscarinic receptors after 7 or 13 days on milk was 32%, and 38% after 21 days; the decreases for rats on Metrecal for 7 days were 32% for females and 35% for males. In rats maintained on liquid (milk) diet for 7 days, and then denervated by unilateral removal of the parasympathetic and sympathetic innervations to parotid there were decreases of 39-42% in number of beta-receptors and 50-52% in muscarinic receptors at 6 or 14 days after denervation (maintenance on liquid diet for 13 and 21 days, respectively) from those of innervated glands of chow-fed rats; denervated glands of rats on chow diet showed the same reduction. Thus, it was concluded that absence of neurally mediated glandular activity, imposed by either diet or surgical removal of the nerves, caused marked decreases in number of both beta-adrenergic and muscarinic receptors, but that the presence of the nerves, even though inactive (liquid diet), provided a trophic influence that prevented the more marked decreases seen in the absence (surgical removal) of the nerves.     

Secretory and structural changes in the parotid salivary gland of sheep and lambs after parasympathetic denervation.

The effect of the parasympathetic nerve supply on the development of the parotid gland in the immature lamb and its maintenance in the adult sheep has been investigated by unilateral postganglionic denervation. Seventy-seven to ninety-three days after denervation secretory activity of the gland was examined and material taken for histological examination. The adult denervated glands secreted at lower rates than the innervated and their atropine-resistant secretory flow was reduced to as low as one fifth of that of the innervated glands. In two lambs an atropine-resistant flow did not develop in the denervated glands: in another two, flows of saliva from the denervated glands were present but were much less than in the contralateral innervated glands. After denervation glands were, with one exception, smaller than the contralateral innervated glands. The acinar cells of the denervated adult and lamb glands were smaller than the cells of the innervated glands but similar in size to those of 7-14 day old unoperated control lambs. Acinar cells in denervated glands had periodic acid Schiff staining material but the staining reaction to pyronin-methyl green was similar in the innervated and denervated. The results indicate that the integrity of the parasympathetic innervation is essential for the development of the parotid gland of the sheep and for its maintenance in the adult animal.     

Immunocytochemical demonstration of nerve growth factor and histofluorescence of catecholaminergic nerves in the salivary glands of diabetic mice

Summary Nerve growth factor (NGF) was localized in the submandibular, sublingual, and parotid salivary glands of male and female diabetic mice and their normal littermates by immunoperoxidase staining usingp-phenylenediamine-pyrocatechol as a chromogen for the cytochemical demonstration of peroxidase activity. In the normal male submandibular gland, immunoreactive NGF was localized in the apical regions of granular, intercalated and collecting duct cells, while in the normal female submandibular gland, NGF was present throughout the cytoplasm of granular duct cells. The localization of NGF in the diabetic male and female submandibular glands was similar and resembled that of the normal female. NGF immunoreactivity was also observed in the striated duct cells in the sublingual and parotid glands of all four types of mice.The sympathetic innervation of the submandibular glands of normal and diabetic mice was demonstrated using glyoxylic acid-induced histofluorescence. The pattern of sympathetic innervation and the intensity of catecholamine fluorescence was consistently different in the four types of mice. In the normal male submandibular gland the fluorescence was very intense, particularly in nerves adjacent to the granular ducts. In the normal female submandibular gland, the fluorescence was weak, while in the diabetic male and female the fluorescence was moderate.The correlation between the intensity of the immunocytochemical staining for NGF and the catecholamine fluorescence adjacent to the granular ducts suggests a trophic influence of the NGF-containing granular ducts on their sympathetic innervation.     

Developmental status of sympathetic innervation in relation to calcium accumulation by submandibular gland following reserpine, surgical sympathectomy or cyclocytidine

Sympathectomy (Sx) of the submandibular gland was induced at various postnatal ages by ip administration of a single dose of reserpine or by unilateral excision of a superior cervical ganglion. If animals were 12 days old or less at the time of drug administration, [Ca] of the submandibular gland was not measurably increased 24 hr later; if rats were 14 days of age or older, [Ca] of the gland 24 hr after reserpine injection was nearly double that of untreated controls. Two days after surgical Sx, [Ca] of the denervated submandibular gland was unchanged from that of the innervated member of a pair if animals were less than 14 days of age at the time of denervation; [Ca] was twice that of glands of control rats if animals were older than 14 days of age when the denervation was performed. The anti-tumor agent, cyclocytidine (CC), given daily for 3 days in an ip dose of 500 mg/kg, also caused a two- to threefold increase in [Ca] of the submandibular gland when rats were more than 12 days of age at the time of the initial injection of the drug, but in rats younger than this age, CC caused no change in the [Ca] of the submandibular gland. Present data show that there are age-related differences in the ability of the submandibular gland to accumulate calcium following sympathetic denervation or treatment with a norepinephrine-releasing drug. These differences may be attributed either to incomplete development of calcium transport mechanisms, or incomplete development of the sympathetic innervation before 14 days of age.     

Cell surface expression of 4 beta-galactosyltransferase accompanies rat parotid gland hypertrophy induced by changes in diet.

Maintenance of rats for 2 weeks on a diet consisting of 50% inert cellulose and 50% laboratory chow resulted in hypertrophy of the parotid gland and a 4-fold increase in total membrane-associated 4 beta-galactosyltransferase enzyme activity (EC 2.4.1.38). Localization of the increased specific activity to the cell surface of the enlarged gland was shown by subcellular fractionation of Golgi and plasma membranes. This observation was confirmed by enzyme assays of intact cells; quantification of immunofluorescence was made by using a fluorescence activated cell sorter. Parotid gland hypertrophy was inhibited by the administration of the specific modifier protein alpha-lactalbumin as well as by a monospecific antibody for 4 beta-galactosyltransferase. These agents also inhibited the incorporation of thymidine into DNA.     

Functional mediation of compensatory enlargement of the parotid gland

Summary The role of functional activity in mediating compensatory enlargement of the parotid gland after removal of the other major salivary glands was investigated. Increased levels of activity were achieved by feeding rats a bulk diet. Conversely, a liquid diet was used to reduce the functional demands on the parotid. It was found that the liquid diet completely prevented the compensatory response from occurring. Bulk diet, on the other hand, caused an even greater compensatory response than did the standard chow diet. Compensatory enlargement of the parotid, therefore, depends on its functional activity and not on other, e.g., humoral factors dissociated from function. The character of the cellular response in compensatory enlargement was also examined. The chow diet caused compensatory enlargement by an increase in cell size with little, if any, increase in cell number.Supported in part by the Veterans Administration and Grant DE 02110 of the U.S. Public Health Service     

The regulation of lipogenesis in vivo in the lactating mammary gland of the rat during the starved-refed transition. Studies wtih acarbose, a glucosidase inhibitor.

Depression of carbohydrate digestion by oral administration of acarbose, a glucosidase inhibitor, led to a 75% inhibition of the re-activation of lipogenesis in vivo in the mammary gland of 18 h-starved lactating rats refed with 5 g of chow diet. Rates of [1-14C]glucose incorporation in vitro into lipid and CO2 in mammary-gland acini isolated from refed animals were elevated compared with acini from starved rats, but acarbose treatment completely prevented this stimulation. Gastric intubation of glucose led to a large stimulation of lipogenesis in the mammary gland of starved lactating rats, similar to that induced by refeeding with chow diet; this was dependent on the amount of glucose given and the time elapsed between glucose administration and injection of 3H2O for the measurement of lipogenesis. The switch-on of lipogenesis in the mammary gland of starved lactating rats, by refeeding or by intubation of glucose, was associated with a decrease in the ratio of [glucose 6-phosphate]/[fructose 1,6-bisphosphate] in the gland, indicative of an increase in phosphofructokinase activity. A time-course study revealed that the ratio decreased rapidly over the first 30 min of chow refeeding, after which a large surge in lipogenesis was seen. Acarbose, given 25 min after the onset of refeeding, led to a stepwise increase in the ratio, in parallel with the observed decrease in lipogenic activity. It is concluded that the control of lipogenesis in the mammary gland is closely linked to the availability of dietary carbohydrate. An important site of regulation of lipogenesis in the gland appears to be at the level of phosphofructokinase. A possible role of insulin in the regulation of phosphofructokinase activity, and the acute modulation of insulin-sensitivity in the gland during the starved-refed transition, are discussed.     

Nerve growth factor-induced increase in [3H]thymidine incorporation into pancreas of young rats and its partial blockade by propranolol or partial sialoadenectomy

Administration of nerve growth factor (NGF) twice daily for 2 days to rats 11 days at the time of the initial injection resulted in a 6.6-fold increase in [3H]thymidine levels of pancreas, when comparison was made to levels of untreated controls. Isoproterenol (ISO), a beta-adrenergic agonist known to produce marked increase in [3H]thymidine incorporation into DNA of salivary glands, caused increases in levels of [3H]thymidine in pancreas that were similar in magnitude to those induced by NGF. The combined administration of ISO and NGF did not cause any increase above those observed with either agent alone. Administration of propranolol (3 mg/kg body wt) prior to administration of ISO prevented the usual ISO-induced increase in DNA synthesis, but propranolol in either a 3- or 9-mg/kg body wt dose, caused only a 50% inhibition of NGF-induced thymidine incorporation. In the absence of the submandibular-sublingual glands, the ISO failed to induce the usual high levels of thymidine incorporation, whereas NGF induced the same high levels observed in rats with submandibular glands intact. NGF did not alter the distribution of beta 1- and beta 2-adrenoceptors in the pancreas but did increase norepinephrine when the initial administration was at age 5 days, but not when it was given at age 10 days. Since NGF increased DNA synthesis in the absence of submandibular-sublingual glands, whereas ISO did not, this suggests that ISO requires NGF to induce beta 1-activation and subsequent synthesis and that NGF is a direct activator.     

Nitric oxide synthase immunoreactive nerves in rat and ferret salivary glands, and effects of denervation

Nitric oxide has been implicated in mechanisms mediating nerve-evoked vasodilatory and secretory responses in salivary glands. In the present study, the occurrence and distribution of nitric oxide synthase (NOS)-immunoreactive nerves in ferret and rat salivary glands were investigated using immunocytochemistry with rabbit and sheep NOS antisera, and using NADPH-diaphorase enzyme histochemistry. In the parotid, submandibular and sublingual glands of the rat and the ferret, NOS-immunoreactive varicose terminals encircled acini and arteries of various sizes. In the ferret, collecting ducts were also supplied with NOS-immunoreactive fibres. In the rat, only the granular ducts of the submandibular gland were supplied with such fibres. The NOS-immunoreactive innervation of acinar cells was more abundant in the rat than in the ferret, whereas the opposite was true for the innervation of blood vessels. No NOS immunoreactivity was observed in the vascular endothelium. In both species, NOS-positive ganglionic cell bodies were found in the hilar regions of the submandibular and sublingual glands, whereas none could be detected in the parotid glands. NADPH-diaphorase reactivity had the same neuronal distribution as NOS immunoreactivity and, in addition, NADPH-diaphorase reactivity was expressed in ductal epithelium. Neither sympathetic denervation (by removal of the superior cervical ganglion) nor treatment with the sensory neurotoxin capsaicin reduced the NOS-immunoreactive innervation of the parotid gland. However, parasympathetic denervation (by cutting the auriculo-temporal nerve) caused an almost total disappearance of the NOS-immunoreactive innervation. The present findings provide a morphological background to the suggested role of nitric oxide in parasympathetic secretory and vascular responses of salivary glands. This revised version was published online in November 2006 with corrections to the Cover Date.     

Acquisition of cholinergic and peptidergic properties by sympathetic innervation of rat sweat glands requires interaction with normal target

The sweat glands, a target of cholinergic sympathetic neurons, were replaced with parotid gland, a target of noradrenergic sympathetic neurons, in neonatal rats. This transplantation paradigm allowed sympathetic neurons that would normally innervate the sweat glands and develop a cholinergic phenotype to innervate the parotid gland instead. The innervation of the transplanted parotid gland did not develop a cholinergic phenotype, as assessed by choline acetyltransferase activity and acetylcholinesterase immunoreactivity, but continued to express intense catecholamine fluorescence. In addition, immunoreactivity for vasoactive intestinal peptide, normally expressed by the sympathetic innervation of the sweat glands but not the parotid, was observed in only a small percentage of the parotid-associated fibers. These results suggest that cellular interactions between neurons and their targets play an important role in the differentiation of mature neurotransmitter and neuropeptide phenotypes in vivo.     

Developmental interactions between sweat glands and the sympathetic neurons which innervate them: effects of delayed innervation on neurotransmitter plasticity and gland maturation

The neurotransmitter properties of the sympathetic innervation of sweat glands in rat footpads have previously been shown to undergo a striking change during development. When axons first reach the developing glands, they contain catecholamine histofluorescence and immunoreactivity for catecholamine synthetic enzymes. As the glands and their innervation mature, catecholamines disappear and cholinergic and peptidergic properties appear. Final maturation of the sweat glands, assayed by secretory competence, is correlated temporally with the development of cholinergic function in the innervation. To determine if the neurotransmitter phenotype of sympathetic neurons developing in vivo is plastic, if sympathetic targets can play a role in determining neurotransmitter properties of the neurons which innervate them, and if gland maturation is dependent upon its innervation, the normal developmental interaction between sweat glands and their innervation was disrupted. This was accomplished by a single injection of 6-hydroxy-dopamine (6-OHDA) on Postnatal Day 2. Following this treatment, the arrival of noradrenergic sympathetic axons at the developing glands was delayed 7 to 10 days. Like the gland innervation of normal rats, the axons which innervated the sweat glands of 6-OHDA-treated animals acquired cholinergic function and their expression of endogenous catecholamines declined. The change in neurotransmitter properties, however, occurred later in development than in untreated animals and was not always complete. Even in adult animals, some fibers continued to express endogenous catecholamines and many nerve terminals contained a small proportion of small granular vesicles after permanganate fixation. The gland innervation in the 6-OHDA-treated animals also differed from that of normal rats in that immunoreactivity for VIP was not expressed in the majority of glands. It seems likely that following treatment with 6-OHDA sweat glands were innervated both by neurons that would normally have done so and by neurons that would normally have innervated other, noradrenergic targets in the footpads, such as blood vessels. Contact with sweat glands, therefore, appears to suppress noradrenergic function and induce cholinergic function not only in the neurons which normally innervate the glands but also in neurons which ordinarily innervate other targets. Effects of delayed innervation were also observed on target development. The appearance of sensitivity to cholinergic agonists by the sweat glands was coupled with the onset of cholinergic transmission.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ultrastructural changes of rat parotid glands induced by a diet of liquid Metrecal

Summary The ultrastructure of parotid glands was studied in rats fed a diet of liquid Metrecal for two weeks and compared with that of parotid glands of control rats which received a diet of Purina lab chow. The liquid diet induced major alterations of acinar cells, but other parenchymal components were apparently unaffected.Most acinar cells of experimental rats were atrophic and some of these were undergoing necrosis. Lipid droplets and dense bodies (believed to be lysosomes) were numerous in atrophic cells. The Golgi apparatus, quantity of secretory granules, and intercellular canaliculi were smaller than in acinar cells of control rats.Such findings suggest that the secretory process was impaired and support the conclusion that parotid glands of rats maintained on a liquid diet are physiologically less active than those of chow fed rats. The decreased activity, as previously reported, may result from reduced masticatory activity.Supported by U.S.P.H.S. grant DE 02110.     

Modification of cyclocytidine-induced changes in [3H]thymidine incorporation and weight of parotid gland by partial sialoadenectomy.

Cyclocytidine (CC), a potent antitumor agent, caused a 2.3- to 5.0-fold increase in [3H]thymidine uptake of rat parotid gland after 3 days of daily administration of 500 mg/kg body wt. Gland weight also showed a 47-67% increase from that of controls. Ablation of the submandibular-sublingual glands prior to initiation of the CC regimen prevented the usual CC-induced increase in [3H]thymidine uptake, but did not inhibit the increase in gland size. It is postulated that CC-induced parotid hyperplasia requires an initial release of growth factors from the submandibular gland; however, enlargement of the parotid gland by CC is independent of such factors.     

Neonatal treatment with nerve growth factor antiserum eliminates cholinergic sympathetic innervation of rat sweat glands

Most mammalian sympathetic neurons are noradrenergic, and their dependence upon nerve growth factor (NGF) for survival during development is well established. A minor population of sympathetic neurons, including those that innervate sweat glands, is cholinergic. To determine whether cholinergic sympathetic neurons, like their noradrenergic counterparts, require NGF during development, neonatal rats were treated with NGF-antiserum and 3 weeks later their sweat glands were examined for the presence of innervation. Acetylcholinesterase (AChE) staining and vasoactive intestinal polypeptide-like immunoreactivity (VIP-IR) which mark the mature sweat gland innervation were absent from the sweat glands of the anti-NGF treated animals. Further, when the glands were examined with the electron microscope, no axons or nerve terminals were evident. These observations indicate that the elaboration of the sweat gland plexus is NGF-dependent and suggest that at least one population of cholinergic sympathetic neurons in the rat requires NGF for survival. Our findings are consistent with the idea that during development NGF is a required trophic factor not only for noradrenergic sympathetic but also for cholinergic sympathetic neurons.     

Postnatal expression and denervation induced up-regulation of aquaporin-5 protein in rat sweat gland

The evolution of aquaporin-5 (AQP5) expression during postnatal development has not been defined in the sweat gland. Previous studies have suggested that AQP isoforms in several peripheral targets are regulated by a neural mechanism. We have examined, in rat sweat glands, the expression of AQP5 during postnatal development and the effects of denervation on AQP5 expression. Both AQP5 mRNA and protein begin to be expressed at postnatal day 10, before sweat-secretory responsiveness first appears; this expression coincides with the occurrence of vasoactive intestinal peptide (VIP) immunoreactivity. Early noradrenergic and later cholinergic interaction between sweat glands and their innervation are disrupted by neonatal chemical sympathectomy or postnatal severance of the sciatic nerve. Examination of such denervated developing rats has shown that secretory responsiveness fails to arise later in the adults, and AQP5 immunostaining increases in the denervated glands, whereas gland morphogenesis and the occurrence of AQP5 expression proceed normally. Immunobloting has revealed an increase of AQP5 abundance after the denervated mature glands lose their secretory ability. These findings suggest that AQP5 protein is necessary for sweat secretion, and that the expression of AQP5 in rat sweat glands is independent of sympathetic innervation. Our data also indicate that factor(s) regulating the normal morphological development of sweat gland might be responsible for controlling AQP5 expression.     

Nervous control of mammalian salivary glands

In the production and flow of saliva, sympathetic and parasympathetic nerves generally cooperate, although variations between the different salivary glands are considerable, particularly in the sympathetic innervation. In the submandibular gland of the dog, sympathetic impulses cause secretion via beta-adrenoceptors, and since sympathetic motor effects are elicited via alpha-adrenoceptors it is possible to study separately motor and secretory effects in this gland. Such experiments indicate that myoepithelial contractions serve to accelerate the salivary flow and to support the secreting acinar cells and prevent back-flow of fluid from the luminal system into the glandular tissues. The contractions are elicited reflexly from the oral mucosa together with secretion. A potentiation interaction between sympathetic and parasympathetic nerves occurs in the formation of the primary saliva. In parotid glands of rabbits and rats such an interaction has been demonstrated in the secretion of amylase.     

Effects of thyrotoxicosis and selective hepatic autonomic denervation on hepatic glucose metabolism in rats

Thyrotoxicosis is known to induce a broad range of changes in carbohydrate metabolism. Recent studies have identified the sympathetic and parasympathetic nervous system as major regulators of hepatic glucose metabolism. The present study aimed to investigate the pathogenesis of altered endogenous glucose production (EGP) in rats with mild thyrotoxicosis. Rats were treated with methimazole in drinking water and l-thyroxine (T(4)) from osmotic minipumps to either reinstate euthyroidism or induce thyrotoxicosis. Euthyroid and thyrotoxic rats underwent either a sham operation, a selective hepatic sympathetic denervation (Sx), or a parasympathetic denervation (Px). After 10 days of T(4) administration, all animals were submitted to a hyperinsulinemic euglycemic clamp combined with stable isotope dilution to measure EGP. Plasma triiodothyronine (T(3)) showed a fourfold increase in thyrotoxic compared with euthyroid animals. EGP was increased by 45% in thyrotoxic compared with euthyroid rats and correlated significantly with plasma T(3). In thyrotoxic rats, hepatic PEPCK mRNA expression was increased 3.5-fold. Relative suppression of EGP during hyperinsulinemia was 34% less in thyrotoxic than in euthyroid rats, indicating hepatic insulin resistance. During thyrotoxicosis, Sx attenuated the increase in EGP, whereas Px resulted in increased plasma insulin with unaltered EGP compared with intact animals, compatible with a further decrease in hepatic insulin sensitivity. We conclude that chronic, mild thyrotoxicosis in rats increases EGP, whereas it decreases hepatic insulin sensitivity. Sympathetic hepatic innervation contributes only to a limited extent to increased EGP during thyrotoxicosis, whereas parasympathetic hepatic innervation may function to restrain EGP in this condition.     

Developmental changes of nerve growth factor levels in sympathetic ganglia and their target organs

The predominant source of nerve growth factor (NGF) used by mature sympathetic neurons originates in their target organs (Heumann, R., Korsching, S., Scott, J., and Thoenen, H. (1984), EMBO J. 3, 3183-3189; Korsching, S., and Thoenen, H. (1985), J. Neurosci. 5, 1058-1061). We have determined the NGF content of two sympathetically innervated mouse organs, submandibular gland and heart ventricle, and of sympathetic ganglia from mouse and rat between embryonic Day 12 (E12) and adulthood. NGF levels were measured by a two-site enzyme immunassay (Korsching, S., and Thoenen, H. (1983), Proc. Natl. Acad. Sci. USA 80, 3513-3516). In heart ventricle and submandibular gland, NGF first became detectable around the time of initial innervation by sympathetic neurons (E12 and E13, respectively) and increased respectively 14- and 7-fold in the following 2 days, to reach adult levels already at E14 for heart ventricle (1.4 +/- 0.2 ng NGF/g wet wt). NGF in the superior cervical ganglion (SCG) was first detected at the same time as in its target organ, the submandibular gland. NGF content in the SCG then increased 6-fold during the next 2 days and continued to increase until the end of the third postnatal week, when adult levels were reached. Although the levels of NGF in the adult mouse submandibular gland are sexually dimorphic and six orders of magnitude higher than those in other sympathetic target organs, no sex difference in the NGF content was found in either developing submandibular gland or SCG until the end of the third postnatal week. Moreover, the steep NGF increase observed in the male submandibular gland after postnatal Day 18 (250-fold within the following 3 days and up to the 55,000-fold in the next 7 days) was not reflected in a corresponding increase in the NGF content of the male SCG. These data indicate that, in accordance with earlier findings (see Levi-Montalcini, R., and Angeletti, P. U. (1968), Physiol. Rev. 48, 534-569), SCG neurons do not have access to the large amounts of NGF synthesized during and after adolescence in the mouse submandibular gland. Our results support the concept that initial fiber outgrowth of sympathetic neurons is neither dependent on NGF nor mediated by it. The time course of NGF levels in the SCG is consistent with the concept that sympathetic neurons are provided with NGF by means of retrograde axonal transport from the innervated organs already early in development.     

Effects of acute starvation on carbohydrate metabolism in rat salivary glands.

1. Effects of acute starvation on enzymes of carbohydrate metabolism were determined in rat submandibular and parotid glands. 2. Activities of glycolytic enzymes were high in submandibular gland, but those of pentose phosphate pathway and glycogen metabolism were high in parotid gland. 3. Enzyme activities were lowered by acute starvation. Refeeding the rats with solid diet restored the enzyme activities, but with liquid diet, only partial recoveries were found in submandibular gland.     

Comparison of effects of surgical and chemical sympathectomy on beta adrenergic and muscarinic receptors of parotid gland of young and adult rats

Surgical (removal of a superior cervical ganglion) or chemical [(administration of a single dose of 6 hydroxydopamine (6 OHDA) (50 mg/kg dose body wt)] sympathectomy of rats at 2 or 8 days of age resulted in an increase in [3H]DHA binding of membranes of parotid gland of young rats (age range 21 days to 48 days). The increase progressed with postnatal age; at 21 days of age (surgical sympathectomy), it was 13%; at 32 days of age with 6 OHDA, it was as much as 34%, but only 26% at 42 days of age with surgical sympathectomy. No change in [3H]QNB binding was observed at any postnatal ages following neonatal sympathectomy. Conversely, surgical sympathectomy of the parotid of adult rat resulted in little or no change in [3H]DHA binding at 1, 2, 3, or 4 weeks postdenervation, but [3H]QNB binding was reduced at all periods, with the reduction from control values at 2 weeks being 34%, and at the subsequent intervals, 24-26%. The increase in number of beta adrenoceptors of the parotid gland was not related to the kind of sympathectomy (chemical or surgical) or neonatal age at which it was done; however, duration of the denervation for 2-3 weeks was necessary for the receptor increase to occur. In the adult, however, the duration of the denervation was of no importance since change in number of beta adrenoceptors did not occur at 1, 2, 3, or 4 weeks after surgical denervation but did occur after only 1 week after of reserpine-induced denervation. QNB binding was decreased with surgical sympathectomy as well as reserpine-induced sympathectomy of adult parotid gland; norepinephrine concentration was decreased to levels of a few percent of innervated glands. The relation between development of glandular supersensitivity and increase in beta adrenoceptors is discussed.