摘要:

As a part of a study aiming to characterize the physiological and pharmacological significance of the high affinity pineal benzodiazepine (BZP) binding sites reported previously, we examined the uptake of the BZP derivative3H‐flunitrazepam (FNZP) by rat pineal glands in vitro. At 37 °C,3H‐radioactivity was taken up by tissue up to a pineal/medium concentration of about 12, while at 0 °C the uptake amounted to only one‐third that at 37 °C. Reciprocal of uptake analyzed by Lineweaver‐Burk plots indicated apparent Km's of 1.74 and 1.45 μM, and Vmax's of 1.32 and 1.04 pmol per min per mg tissue, for control and superior cervical ganglionectomized rats, respectively, suggesting that the neural compartment does not participate significantly in3H‐FNZP uptake. Cerebral cortex explants of similar size and weight as the pineal ones took up3H‐FNZP to a maximum tissue/ medium concentration of about 2. Neither pineal nor cerebral cortex3H‐radioactivity uptake exhibited significant changes as a function of time of day. A number of agents, including several BZP analogues, cocaine, desipramine, melatonin, fluoxetine, nomifensine, and dipiridamol, as well as changes in the ionic environment or metabolic inhibitors, did not affect3H‐FNZP uptake significantly. Other tissues, such as liver, muscle, kidney, adrenal gland, or anterior pituitary, took up3H‐radioactivity to tissue concentrations slightly lower than those of the cerebral cortex, suggesting that drug liposolubility accounted only to a limited extent for the high in vitro uptake detected

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00212.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

In addition to β‐adrenergic receptor agonists, L‐dopa and dopamine have been also shown to activate the production of melatonin and its synthesizing enzyme, serotonin N‐acetyltransferase. In an attempt to characterize dopaminergic receptor sites, bovine pineal synaptosomes were prepared by differential centrifugation techniques. Washed disrupted synaptic membranes were used to study3H‐spiroperidol binding, using standard membrane‐binding techniques. Association of3H‐spiroperidol to pineal membranes was very rapid, reaching equilibrium within 2 min and remaining stable for 20 min. Dissociation was also rapid with a t½ of 3 min. Analysis of saturation studies (0.035 to 20 nM spiroperidol, 16 concentrations) using the LIGAND program indicated the presence of two binding sites with KDs (dissociation equilibrium constant) of 0.18 nM and 2.1 nM. The Bmax's (receptor density) of the sites were 37 and 630 fmoles/mg protein respectively. The IC50s of haloperidol, cis‐flupenthixol, and chlorpromazine were 8, 12, and 80 nM, respectively, while those of pipamperone, cyproheptadine, and cinanserin were 60, 400, and 1500 nM. These and other data indicate that the most abundant site is a dopamine D2 receptor while the less abundant site may be a serotonin receptor. The function of dopamine and dopaminergic neurons in bovine pineal gland is not known and has not b

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00213.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The distribution and disappearance of melatonin and N‐acetylserotonin after intravenous injection were studied at mid‐light and mid‐dark. Male rats were adapted under a photoperiod of 12 h light and 12 h dark cycle for a minimum of 1 week. After the intravenous injection of melatonin (10 μg), N‐acetylserotonin (10 μg), or3H‐melatonin (76 ng), blood samples were collected at 1, 3, 5, 10, 20, 30, 45, 60, 75, 90, and 120 min. The concentrations of indoles in the plasma samples were determined by radioimmunoassay, while the radioactivity of3H‐melatonin was determined by scintillation counting.The distribution of melatonin and N‐acetylserotonin followed a two‐compartment model, showing an initial distribution phase followed by an elimination phase. The biological half‐life of melatonin at mid‐light and mid‐dark were similar but the volume of distribution (Vβand Vc.) and metabolic clearance rate (C1s) were greater at mid‐dark than at mid‐light. The estimated melatonin secretory rate at mid‐dark was fivefold greater than that at mid‐light. When3H‐melatonin was used, the half‐life was significantly longer. A diurnal difference in the distribution was also evident in the N‐acetylserotonin studies. The volume of distribution (Vβand Vc) was greater at mid‐dark while the CIswas not significantly faster at mid‐dark compared with that at mid‐light. However, the estimated N‐acetylserotonin secretory rate at m

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00214.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The influence on the ultrastructure of pinealocytes of long‐term hyperprolactinemia caused by ectopic pituitary transplants and of suppression of prolactin release by bromocriptine was examined morphometrically in male rats. Hyperprolactinemia resulted in an increase in the relative volumes of granular endoplasmic reticulum, vacuoles containing a flocculent material, mitochondria, and lipid droplets. Treatment of grafted rats with bromocriptine reversed the effects of hyperprolactinemia. However, bromocriptine had no apparent influence on the pinealocytes of intact rats. The effects of hyperprolactinemia on the ependymallike secretory process in the pinealocyte were especially pronounce

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00215.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The neural connections between the pineal organ and the brain were investigated in two teleost species: the crucian carp and the European eel. Horseradish peroxidase (HRP) was administered into the pineal parenchyma in vivo or in vitro. After 12–96 hours, the brains were fixed, and HRP was reacted in frozen sections with either diaminobenzidine (DAB) or Hanker‐Yale's reagent. The HRP had entered the pineal neurons, and had labeled their axonal processes (the pineal tract) in a Golgi‐like manner. In both species, HRP‐labeled axons were observed in the habenular nuclei, the pretectal area, the dorsal and ventral thalamus, the dorsal periventricular tegmentum, and in the posterior periventricular hypothalamus. In the eel, single axons were also observed in the anterior hypothalamus and in the brain stem. Thin, varicose (preterminal) axons were observed in great numbers in the pretectal area and dorsal thalamus in both species, and in small numbers in the habenular nuclei and posterior periventricular hypothalamus. For comparison, the retinofugal projections were visualized after intraocular HRP‐injection. A close association of retinal and pineal terminal fields were noted in the pretectal area and the dorsal thalamus, whereas other diencephalic retinal and pineal recipient areas seem more s

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00216.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The purpose of this study was to define the peripubertal changes in prolactin (PRL) synthesis in blind‐anosmic female rats. To do this prepubertal female rats were either rendered blind‐anosmic (BA) or blind‐anosmic‐pinealectomized (BAP) or left intact (INT). Half the animals were killed after 1 wk (before puberty) while the remaining animals were terminated after 4 wk (after puberty). Pituitary PRL synthesis was measured by the in vitro incorporation of3H‐leucine into PRL. Anterior pituitary weight and DNA content did not differ between BA, BAP, and INT animals 1 wk after treatment. There was a 65% increase in weight and a 55% increase in DNA content in INT pituitaries between I and 4 wk. White these increases were also present in BAP rats, they were almost entirely prevented in BA animals. PRL synthesis followed a similar pattern with a 78% increase in synthesis in INT groups between 1 and 4 wk which was, once again, almost entirely absent in BA rats. Pinealectomy prevented this effect. Blinding and anosmia in postpubertal animals produced only a minor decrease in PRL synthesis and pituitary weight and no decrease in pituitary cell number. From these data we conclude that the pineal can inhibit the normal proliferation of PRL cells that occurs during puberty in blind‐anosmic

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00217.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Chronic electroconvulsive shock (ECS) did not significantly alter pineal concentrations of melatonin. Statistically significant decreases of serotonin, however, were found in both the pineal and hypothalamus. These results support the previous reports of serotoninergic receptor supersensitivity following repeated ECS, and suggest serotoninergic involvement but do not necessarily exclude adrenergic involvement in the antidepressant effect of electroconvulsive therapy.

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00218.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Intercellular relationships of sympathetic nerve fibers and cells in pineal glands of Long‐Evans rats and yellow‐bellied country rats (Rattus losea Swinhoe) were studied with conventional electron microscopy. Typical synapses were found between adrenergic axon varicosities and pinealocytes. The synaptic cleft was 20–30 nm thick and contained granular or filamentous material of moderate electron density. Some small granulated vesicles attached to, or fused with, the presynaptic axolemma, a feature suggesting an exocytotic release of the vesicle content. The occurrence of membranous cisternae or tubules in the synaptic nerve ending may connote the phenomenon of synaptic vesicle recycling. Beneath the postsynaptic pinealocyte plasmalemma there was a dense plaque corresponding to the postsynaptic density of neurons. Possible origins and functional significance of the synapse‐making nerve fibers are also di

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00219.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Electron microscopic observations on pinealocytes of cotton rats (Sigmodon hispidus) killed in October revealed the presence of cytoplasmic inclusion bodies (CIBs) and two kinds of nuclear inclusions—coiled bodies and granular inclusion bodies. These inclusions were usually not bounded by a membrane. CIBs showed round or irregular profiles and consisted of granular and filamentous materials of moderate electron opacity intermingled with electron‐lucent areas. Nuclear granular inclusions appeared as homogeneous or heterogeneous granules of variable electron opacity, which usually exhibited round profiles of variable diameters and consisted of granular and filamentous elements. Electron‐opaque granules were observed in perinuclear spaces, dilated cisternae of rough endoplasmic reticulum, as well as in the central portion of CIBs. In CIBs containing granules, the peripheral region was composed of the moderately electron‐opaque substance seen in usual CIBs, while the central core was occupied by a granular and filamentous substance and an intervening electron‐lucent matrix. Since an electron‐opaque granular substance in nuclei, perinuclear spaces, cisternae of rough endoplasmic reticulum, and the central portion of CIBs may occur concomitantly, the granules seen in these sites may be related. Coiled bodies were round in profile and were composed of electron‐opaque strands consisting of granular and filamentous elements and intervening material of low electron opacity. This structure, frequently located in close proximity to the nuclear granular inclusions, may play a role in the formation of the intranuclear granules in cotton rat

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1984.tb00220.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY