Enhancement of salivary secretion and neuropeptide (substance P, alpha-calcitonin gene-related peptide) levels in saliva by chronic anethole trithione treatment.

Anethole trithione, a choleretic, has been reported to be effective in the treatment of dry mouth. We have examined the effects of chronic treatment with anethole trithione on salivary secretion, substance P immunoreactive substance (SP-IS) and alpha-calcitonin gene-related peptide immunoreactive substance (alpha-CGRP-IS) concentrations in human saliva. Anethole trithione caused significant increases of saliva SP-IS concentrations from the day 13 (25.3 +/- 1.6 pg mL(-1)) to day 14 (25.8 +/- 1.7 pg mL(-1)) compared with day 1 (19.9 +/- 1.9 pg mL(-1)). Anethole trithione caused significant increase in saliva alpha-CGRP-IS concentration on day 14 (39.9 +/- 4.7 pg mL(-1)) compared with day 1 (27.7 +/- 4.7 pg mL(-1)). Anethole trithione significantly increased the sialosis volumes from day 11 to day 14 (1.6 +/- 0.1-1.7 +/- 0.2 mL) compared with the day 1 (1.2 +/- 0.2 mL). Simple linear regression of the increase in sialosis volume with saliva SP-IS (r = 0.94) and alpha-CGRP-IS (r = 0.97) concentrations was found. These results demonstrated that chronic treatment with anethole trithione affected saliva SP-IS and alpha-CGRP-IS concentration in human saliva and sialosis volume.     

Inhibitory actions of methionine-enkephalin and morphine on the cat carotid chemoreceptors

1 The effects of intracarotid injections of methionine-enkephalin (Met-enkephalin) and morphine on chemoreceptor activity recorded from the peripheral end of a sectioned carotid sinus nerve have been studied in cats anaesthetized with pentobarbitone. 2 Met-enkephalin caused a rapid, powerful, inhibition of spontaneous chemoreceptor discharge, the intensity and duration of which was dose-dependent. 3 Morphine was a less potent inhibitor of spontaneous chemoreceptor discharge, and the inhibition it evoked was rather variable and tended to be biphasic. Low doses of morphine caused a slight increase in discharge. 4 Naloxone (0.2 mg i.c.) slightly increased spontaneous discharge, greatly reduced the chemo-inhibition caused by morphine, and reduced the inhibitory effect of Met-enkephalin. A higher dose of naloxone (0.8 mg) caused a substantial reduction of the Met-enkephalin effect. 5 Chemo-excitation evoked by intracarotid injections of acetylcholine, CO2-saturated Locke solution, and sodium cyanide were only slightly and somewhat variably reduced following injections of Met-enkephalin, whereas the inhibitory effect of dopamine was potentiated. Following morphine administration, response to acetylcholine and sodium cyanide were reduced slightly, whereas those to CO2 and dopamine were potentiated. 6 Responses to acetylcholine and CO2 were slightly potentiated during infusion of Met-enkephalin (50 micrograms/min, i.c.) and the response to sodium cyanide was slightly reduced. 7 It is concluded that naloxone-sensitive opiate receptors are present in the cat carotid body; when activated they cause inhibition of spontaneous chemoreceptor discharge. The physiological role of these receptors and the identity of any endogenous ligand remains to be established.     

Effects of repeated infusions of substance P and vasoactive intestinal peptide on the weights of salivary glands subjected to atrophying influences in rats.

1. The long-term influence of substance P (SP) and vasoactive intestinal peptide (VIP) on rat salivary gland weight was investigated after parasympathetic denervation or on feeding soft food. 2. The parotid gland lost about one-third of its weight within 4-5 days following parasympathetic post-ganglionic denervation or change in dietary regimen, from pellets to liquid diet, thought to reduce nerve reflex activity. 3. Daily i.v. infusions with SP or VIP diminished or largely prevented the fall in parotid gland weight, whereas infusions with pentagastrin, bethanechol and saline had no effect. The infusions were preceded by administration of alpha- and beta-adrenoceptor antagonists; these antagonists were also given to the control animals. 4. The effect of SP and VIP on the parotid gland weight appeared to be related to cell size rather than to cell number, as judged by measurements of RNA and DNA. 5. Observations on the two other major salivary glands underlined the fact that different gland types in the same animal behave differently. Parasympathetic preganglionic denervation (decentralization) lowered the weights of the sublingual and submandibular glands, whereas liquid diet only reduced the weight of the sublingual gland. SP and VIP did not affect the weights of the submandibular glands, but VIP prevented the slight fall in sublingual gland weight induced by liquid diet. 6. The present results suggest a trophic role in rats for SP and VIP on parotid glands and for VIP on sublingual glands. Such an influence may be exerted naturally as a result of their release from nerves containing these peptides around acini.     

有氧游泳训练对大鼠条件性位置偏爱及海马中内阿片肽水平的影响

阿片类药物依赖的产生是一个非常复杂的过程,其确切机制至今仍未阐明.最近的研究发现[1],尽管运动本身具有产生奖赏效应的潜力,但能降低吗啡依赖大鼠的自我给药[2].     

Effect of substance P on dopamine-beta-hydroxylase and phenethanolamine-N-methyltransferase in the adrenal glands of rats

Resulting from literature data concerning interactions between catecholamines and Substance P (SP) the influence of SP on the activity of dopamine-beta-hydroxylase (DBH) and phenylethanolamine-N-methyltransferase (PNMT) was studied in rat adrenals. Intraperitoneal application of SP (500 micrograms/kg) to male Wistar rats 15 minutes before decapitation induced a decrease of PNMT activity in the adrenals, while DBH activity remained unchanged. After incubation of adrenals with SP (10(-6) mol/l) a decrease of activity of both PNMT and DBH was observed. The experimental results are discussed in connection with a normalizing function of SP during stress induced disorders.     

Levels of dynorphin peptides, substance P and CGRP in the spinal cord after subchronic administration of morphine in the rat.

Rats were rendered dependent on morphine by repeated injections of morphine, in increasing doses for 14 days and sacrificed. Levels of peptides in the dorsal spinal cord and dorsal root ganglia were analyzed in rats decapitated 2 hr, 24 hr (acute abstinent) or 7 days (late abstinent) respectively, after the last injection of drug. Dynorphin A was significantly decreased in rats abstinent for 24 hr, while dynorphin B remained unaffected. Substance P and CGRP, both putative transmitters in nociceptive primary afferent neurones, and partly existing together in the same neurone, were affected differently. Significantly less substance P but unchanged levels of CGRP were detected in rats abstinent for 24 hr, while on the other hand, CGRP but not levels of substance P, were increased 2 hr after the final injection. In dorsal root ganglia, levels of substance P were lower at 2 hr, while levels of CGRP were unaffected. In late (7 days) abstinence, no effect of opiate on any peptide was detected.     

Analysis of protein synthesis in rat salivary glands after chronic treatment with beta-receptor agonists and phosphodiesterase inhibitors

Chronic administration of the beta-adrenergic receptor agonist isoproterenol (5 mg/200 g animal for 10 days) resulted in rat parotid and submandibular gland hypertrophy, and it induced synthesis of a series of proline-rich proteins (PRPs) and glycoproteins. Treated parotid glands additionally exhibit an increase in activity for the Golgi membrane enzyme UDP-galactose; N-acetylglucosamine 4 beta-galactosyltransferase. A series of beta-receptor agonists and phosphodiesterase inhibitors were examined for their abilities to influence salivary gland protein biosynthesis in a fashion similar to that observed with chronic isoproterenol treatment. beta 1/beta 2-Adrenergic-receptor agonists exhibited the greatest effects on parotid gland hypertrophy and PRP biosynthesis. These beta-agonists were also able to increase 4 beta-galactosyltransferase activity, but they did not promote the synthesis of a 220,000 dalton glycoprotein. Terbutaline (beta 2-receptor agonist) induced parotid gland hypertrophy but was only able to induce protein biosynthesis at higher drug concentrations. Finally, methoxyphenamine was unable to produce the observed changes in protein synthesis even at increased drug dosages. The phosphodiesterase inhibitors (theophylline and caffeine) were able to induce de novo PRP biosynthesis at drug doses of 20 mg/200 g animal. However, while causing mild gland hypertrophy, there was no observable change in 4 beta-galactosyltransferase activity with either phosphodiesterase inhibitor. This same regimen of beta-receptor agonists was unable to induce submandibular gland hypertrophy, PRP or glycoprotein biosynthesis in the same animals. This was also true for the two phosphodiesterase inhibitors. Co-injection of a beta 1 antagonist along with isoproterenol blocked the above protein changes in both the submandibular and parotid glands, suggesting that the stimulation of protein synthesis takes place by beta 1-type receptors on the gland cell surfaces.     

Presynaptic effects of morphine and methionine-enkephalin in feline spinal cord.

The effects of morphine (applied either iontophoretically in substantia gelatinosa or injected intravenously) and met-enkephalin (iontophoretically) were examined on the terminal excitabilities of single sural C, post-A_δ and A_δ afferents, in cats that were decerebrated and then spinalized. Small amounts of morphine (0.1–2.0 mg/kg or 15–80 nA) and met-enkephalin (15–80 nA) produced an increase in the threshold for antidromic activation of these sural fibres. In these doses, the opiate and the opioid peptide potentiated the enhancement of sural afferent terminal excitability produced by superficial peroneal (SP) nerve stimulation. The above effects of both agonists were antagonized by small doses of naloxone (0.05–0.15 mg/kg or 20–40 nA). In large amounts, morphine (3.2–6.4 mg/kg or 50–150 nA) and met-enkephalin (60–150 nA) increased the excitabilities of the sural afferent terminals and antagonized the enhancement of the terminal excitability produced by SP nerve stimulation. These actions by large doses of the agonists were not consistently antagonized by naloxone. In some experiments in which the peripheral nerves, except a few post-A_δ fibres from which recordings were made, were left intact, intraarterially injected bradykinin (10 μg, to a hind limb) produced a decrease in threshold for antidromic activation of the post-A_δ fibres and converted the increase in threshold produced by small amounts of morphine and met-enkephalin into a decrease in threshold. Morphine (0.8–6.4 mg/kg or 30–200 nA) did not consistently alter the excitabilities of muscle group I afferent terminals.The results of these studies indicate that morphine- and met-enkephalin-induced analgesia is, at least, partly due to the ability of the agents to potentiate “presynaptic inhibition” of nociceptive pathways in the spinal cord.     

Mechanism of substance P-induced salivary secretion in the rat: effect of substance P on autonomic nervous system and prostaglandin synthesis (author's transl)

Salivary flow and amylase secretion induced by substance P(SP) administered intraventricularly were considerably less than that by SP given intravenously (i.v.). Salivary flow induced by SP (i.v.) was partially inhibited by baclofen, atropine, d-tubocurarine, alcuronium, phenylephrine and PGE2, while it was enhanced by arachidonic acid and indomethacin. Salivary amylase secretion induced by SP given i.v. was enhanced markedly by isoproterenol, phenoxybenzamine, phentolamine and No. 865-123 (an adrenergic neuron blocking agent), and moderately by baclofen, PGE2 and arachidonic acid, while it was not influenced by propranolol. The enhancements of amylase secretion by adrenergic alpha-blockers were completely inhibited by propranolol. The in vitro examination using rat brain synaptosomes showed that SP promoted markedly the synthesis of PGs, especially of PGE2. These results suggest that the SP-receptor has a nicotinic receptor-like property and may be closely related to adrenergic alpha-receptors situated postsynaptically and presynaptically and to postsynaptic PGE2-receptors. From these results, it is concluded that SP-induced salivary flow and amylase secretion are modulated by the promotion of PGs synthesis in the autonomic nervous system.     

Effects of methionine-enkephalin and morphine on spontaneous locomotor activity: Antagonism by naloxone

Methionine-enkephalin (MEK), a postulated endogenous ligand for the opiate receptors, when administered intracerebroventricularly (ICV) in a dose of 1.75 μmoles/kg) of morphine sulfate had no effect on motor activity. Higher doses (7.0 μmoles/kg) of both MEK and morphine produced profound depression in motor activity; the decrease was significant from 6 to 30 min after their administration. Subcutaneous administration of naloxone (1 mg/kg) did not alter the motor activity. However, administration of naloxone (1 mg/kg) 2 min prior to MEK (7.0 μmole//kg) administration completely blocked the effect of the latter for 15 min while antagonizing the effect of 7.0 μmoles/kg of morphine for 10 min. At 30 min after 7.0 μmoles/kg of either MEK or morphine administration, the motor activity in these groups was identical with that of the naloxone treated group. Methionine-enkephalin in doses of 0.2 and 0.4 μmole/kg had no effect on motor activity for 1 hr observation period. A significant increase in motor activity was recorded 45 and 60 min after 0.2 μmole/kg of morphine sulfate, whereas 0.4 μmole/kg dose of morphine showed significant increase in motor activity only at 60 min after its administration. Furthermore, 0.2 μmole/kg of morphine produced a greater increase in motor activity compared with 0.4 μmole/kg dose at 45 and 60 min after administration. It is concluded that morphine and MEK produce differential effects on mouse spontaneous motor activity with respect to time and dose and that naloxone can inhibit the effects of MEK more effectively than that of morphine on motor activity.     

拮抗触液核P物质对吗啡戒断大鼠行为学的影响

目的观察P物质(substance P,SP)在吗啡戒断大鼠触液核内的表达及拮抗触液核内SP对吗啡戒断行为学的影响,探讨触液核内SP在吗啡戒断中的作用。方法 SPF级SD♂大鼠2组,吗啡戒断-人工脑脊液组(A组)和吗啡戒断-SP抑制剂组(B组);两组均采用剂量递增法腹腔注射盐酸吗啡,建立大鼠吗啡依赖模型,在d4上午侧脑室注射霍乱毒素亚单位B-辣根过氧化物酶复合物(CB-HRP)逆行追踪触液神经元;B组d5上午在立体定位仪下侧脑室注射SP拮抗剂(D-Pro2、D-Phe7、D-Trp9)-SP,A组注射人工脑脊液作为对照组;d6上午腹腔注射纳络酮(5mg·kg-1)建立吗啡戒断模型;并进行戒断行为学评分、记录戒断总评分(total withdrawal scores,TWS),免疫荧光结合激光共聚焦显微镜观察SP的表达。结果 A组大鼠触液核内SP表达增加,B组显示,拮抗触液核内SP可减弱吗啡戒断样症状;两组TWS相比较,A组高于B组(P<0.01)。结论抑制触液核内SP能够减轻吗啡戒断症状,本研究首次证实触液核SP表达参与了吗啡躯体依赖的发展与纳洛酮药物催促戒断,这将有助于利用药理学手段干预阿片依赖寻找新方法。     

Excitatory effect of morphine and opioid peptides in the rat isolated colon

Morphine and the opioid peptides cause isolated segments of rat colon to contract and relax rhythmically. This study re-examines two hypotheses to explain this phenomenon: Release of 5-hydroxytryptamine (5-HT)/acetylcholine by morphine or inhibition of a tonically active non-adrenergic, non-cholinergic (NANC) inhibitory mechanism. Rhythmic contractions induced by morphine (5 x 10(-6) M) were naloxone sensitive (10(-6) M) but unaffected by methysergide (10(-6) M), atropine (10(-6) M) or pretreatment of rats with p-chlorophenylalanine (200 mg kg-1 i.p. for four days) which lowered the 5-HT level in the colon from 3.73 +/- 0.83 mg g-1 in controls to 0.41 +/- 0.06 mg g-1 (P less than 0.001). The pattern of rhythmic contractions produced by morphine was unlike those produced by 5-HT (5 x 10(-6) M), acetylcholine (5 x 10(-6) M) or potassium chloride (30 mM). Tetrodotoxin (10(-6) M), apamin (10(-8) M), clonidine (2 x 10(-8) M), phentolamine (10(-5) M) or oxprenolol (10(-5) M) caused rhythmic contractions which were unaffected by naloxone. Clonidine contractions were inhibited by yohimbine (10(-7) M) but not by prazosin (10(-6) M). Electrical field stimulation at the peak of a contraction induced by morphine, apamin or clonidine, produced an inhibitory response which was unaffected by atropine, phentolamine, propranolol and guanethidine (all 10(-5) M). It persisted in colon segments from the rats with reserpine or 6-hydroxydopamine. These results suggest that neither the 5-HT/acetylcholine hypothesis nor inhibition of the NANC mechanism adequately explains the excitatory effect of morphine in the rat colon.     

Changes in fixed-interval behavior during chronic morphine treatment and morphine abstinence in rats

Rats previously trained to a fixed-interval schedule (FI 2 min) were treated twice daily with saline or morphine hydrochloride (final dose 40 mg/kg i.p.) for 44 days.On day 45 an abstinence state was induced by withdrawing morphine or by giving nalorphine (1 mg/kg i.p.). Operant behavior was recorded on alternate days during the period of chronic treatment and during the withdrawal phase (21 days). It was found that the number of lever presses decreased significantly during the first days of morphine administration but increased later over the control values. The quarter-life was not changed during this period. Morphine withdrawal and nalorphine treatment both caused a further increase in lever presses that lasted about 11 days. Again quarter-life was not changed. These results indicate that the effects of morphine on FI behavior in rats not only undergo tolerance but are actually reversed during the chronic treatment.The data obtained during the withdrawal phase are discussed in relation to the secondary abstinence syndrome described by Martin et al. (1963).     

The effect of corticosterone on extraneuronal amine uptake and effector response in rat salivary glands

The effect of corticosterone on effector cell response to noradrenaline in vivo and on extraneuronal amine uptake in vitro has been investigated in rat submaxillary glands. When tissue slices were incubated with [³H]noradrenaline the level of extraneuronally retained radioactive material was found to be markedly reduced at a concentration of 10 μg ml^?1 of corticosterone after inhibition of neuronal uptake by protriptyline. Corticosterone in a dose of 10 mg kg^?1 was found to markedly potentiate the secretory response to noradrenaline in vivo, when the neuronal uptake of noradrenaline was blocked by protriptyline (10 mg kg^?1, i.p.). Inhibition of neuronal uptake alone by protriptyline or of the extraneuronal uptake alone by corticosterone in the doses used here did not affect the dose-response curve for noradrenaline, at least not in its lower part. The data thus clearly show that the extraneuronal amine uptake of rat salivary glands is blocked by corticosterone and that this extraneuronal uptake might be regarded as a mechanism of importance for the inactivation of the adrenergic transmitter.     

Antidiuretic effect of beta-endorphin and morphine in Brattleboro rats: development of tolerance and physical dependence after chronic morphine treatment.

1 beta-Endorphin (2 micrograms injected into the lateral ventricles) produced a significant decrease in the urine outflow and in the excretion of Na+ and K+ in Brattleboro rats, animals suffering from severe diabetes insipidus. Morphine intracerebrally also produced antidiuresis, as compared to saline-treated controls. 2 Morphine injected intraperitoneally caused a dose-dependent decrease in the urine outflow, and in the excretion of Na+ and K+. 3. Rats chronically treated with morphine (72 h of morphine pellet implantation) were less sensitive to the antidiuretic effect of a challenge dose of morphine than control Brattleboro rats implanted with placebo pellets, but otherwise treated similarly. 4 After chronic morphine administration, Brattleboro rats became dependent on morphine. Challenge with 1 mg/kg naloxone (s.c.) precipitated an abrupt opiate withdrawal syndrome characterized, among other symptoms, by increased urination in contrast to the antidiuresis observed before naloxone.     

Distribution of substance P in the rat gastrointestinal tract — Lack of effect of capsaicin pretreatment

A new method for extraction of immunoreactive substance P (I-SP) from rat intestine including pulverization of tissue frozen in liquid nitrogen and extraction with acid acetone is described. Using this method, amounts of I-SP in the rat intestine were found to be higher than previously reported. The highest concentrations of I-SP were found in the small intestine. Capsaicin pretreatment of newborn or adult rats had no effect on intestinal I-SP concentrations indicating that intrinsic SP neurones are capsaicin-insensitive.