Characterization and measurement of [125I]iodopindolol binding in individual rat pineal glands: existence of a 24-h rhythm in β-adrenergic receptor density

Gonzalez‐Brito, Aldo; Jones, David J.; Ademe, Rosa M.; Reíter, Russel J.

doi:10.1016/0006-8993(88)91329-7

Cited by 37 publications

(18 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even so, light versus dark comparisons demonstrate that [ii-receptor concentrations remain higher during the dark phase. In addi tion, the pineal gland is one brain region where a similar pattern of (ii-receptor concentrations occurs in intact proestrous and estradiol-treated ovariectomized rats, and this pattern is similar to that observed in male rats by Gonzalez-Brito et al [42],…”

Section: Discussionsupporting

confidence: 61%

See 1 more Smart Citation

Diurnal Rhythmicity of Beta-1- and Beta-2-Adrenergic Receptors in Ovariectomized, Ovariectomized Estradiol-Treated and Proestrous Rats

Weiland

Wise²

1989

Neuroendocrinology

View full text Add to dashboard Cite

The effect of norepinephrine on LH is complex: the ovarian steroidal milieu appears to determine whether norepinephrine stimulates or inhibits LH secretion. It has been proposed that steroids allow norepinephrine to have opposite effects on LH by altering the relative concentrations of α₁-(stimulatory) and β-(inhibitory) adrenergic receptors in the hypothalamus. Thus, many investigators have argued that estradiol may permit norepinephrine to stimulate LH release by increasing the density of α₁- and decreasing the density of β-adrenergic receptors in one or more key hypothalamic regions. To test this hypothesis specifically, we measured the density of β₁- and β₂-adrenergic receptor densities in proestrous, ovariectomized, and ovariectomized estradiol-treated rats at various times of day to determine (1) whether the densities of β-receptors exhibit diurnal rhythmicity, (2) whether β-receptors decrease during the time of increased LH secretion and/or (3) how steroidal milieu influences the density and/or the rhythm of receptor densities. The densities of β₁- and β₂-receptors exhibit a diurnal rhythm in some brain areas. These rhythms are detectable only in proestrous and ovariectomized rats and only in selected brain regions. Estrogen treatment has opposing effects in different brain regions. It suppresses the rhythm of β₁-receptor concentrations in ovariectomized rats and also suppresses the average density of receptors in the suprachiasmatic nucleus and pineal gland. In contrast, estrogen increases the density of β₁-receptors in the medial preoptic nucleus. In summary, the results of this study demonstrate that the diurnal rhythm in β-receptors and the effect of estradiol correlate with previously reported changes in receptor-mediated functions. In addition, they reveal the complex interactions of time of day and steroidal milieu on the density of β₁- and β₂-receptors in various brain regions. Finally, the data strongly suggest that decreases in the densities of β-receptors cannot explain the timing of the proestrous or estradiol-induced LH surge or the ability of norepinephrine to inhibit LH release in ovariectomized rats or stimulate LH release in steroid-treated rats.

show abstract

Section: Discussionsupporting

confidence: 61%

“…Rhythms in the densities of (5-adrenergic receptors in the pi neal glands of male rats have been reported previously in which peak density occurs just prior to lights off [40,41 ] or at the mid dle of the dark phase [42]. In ovariectomized female rats, a substantial increase in Pi-receptor densities occurs late in the dark phase.…”

Section: Discussionmentioning

confidence: 89%

Diurnal Rhythmicity of Beta-1- and Beta-2-Adrenergic Receptors in Ovariectomized, Ovariectomized Estradiol-Treated and Proestrous Rats

Weiland

Wise²

1989

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…In the rat pineal gland the p-adrenergic recep tors are of the pr subtype [28,29], It could be argued that the different feed ing schedules of the food-restricted and old rats fed ad libitum explains the differences in p-adrenergic receptor density in their pineal glands. This possibility seems unlikely be cause the pineal P-adrenergic receptor density rhythm that has been reported [18,24] is a function of NE release at night [23] and is not believed to be influenced in a major way by other factors.…”

Section: Discussionmentioning

confidence: 99%

“…The [l25I]iodopindolol ([,25I]P1N) binding study for (3-adrenergic receptors uses a modified version of a method described previously for pineal tissue [18]. Two pineals from each group were pooled and soni cated twice (Cell Disruptor Sonicator.…”

Section: Methodsmentioning

confidence: 99%

Age-Associated Reduction in Pineal Beta-Adrenergic Receptor Density Is Prevented by Life-Long Food Restriction in Rats

et al. 1992

Self Cite

View full text Add to dashboard Cite

At 28 months of age (old rats), male Fisher 344 rats which had been fed 40% of the ad libitum food intake since they were 6 months old, had a similar β-adrenergic receptor density (B_max) in their pineal gland as young, 3-month-old rats. In contrast, old rats which had been fed ad libitum for the same period had approximately 50% of the B_max value compared to that of young rats. The β-receptor density of cerebral cortical tissue and the β-receptor affinity (K_d) of both the cortex and the pineal gland did not decline with age and was not affected by food restriction. The reduction in pineal β-receptor density with age may be causally related to the concurrent age-associated decline in pineal production of melatonin.

show abstract

“…In the rat, for example, an ob vious rhythm in pineal [1-receptor density has been described with maximal number of receptors being present during dark ness [8,16]. Few data are available concerning the effect of isoproterenol ordibutyryl cyclic AMP on the Syrian hamster pineal gland in organ culture [4.…”

Section: Discussionmentioning

confidence: 99%

Stimulatory Effect of Isoproterenol but Not of Dibutyryl Cyclic AMP on N-Acetyltransferase Activity and Melatonin Content of Syrian Hamster Pineal Gland in Organ Culture

et al. 1988

Self Cite

View full text Add to dashboard Cite

The purpose of this study was to compare the response of Syrian hamster pineal glands in organ culture either to isoproterenol, a β-adrenergic agonist, or to dibutyryl cyclic AMP. When pineal glands were collected at night, hamsters were exposed to light for 30 min to depress pineal N-acetyltransferase (NAT) activity and melatonin values to low levels. Pineal glands were removed and placed in organ culture containing either isoproterenol or dibutyryl cyclic AMP and subsequent changes in NAT activity and melatonin levels were measured. At night, isoproterenol (10^–7 or 10^–6M) induced an increase in the NAT activity and melatonin levels in both pineals and culture media. However, dibutyryl cyclic AMP was either ineffective or minimally effective in stimulating these parameters at either different incubation times (2,4, and 6 h) or drug concentrations (0.1, 0.5, and 1.0 mM). Conversely, when rat pineal glands were incubated with either isoproterenol (10–⁷) or dibutyryl cyclic AMP (0.5 mM) dramatic rises in NAT activity and melatonin levels were observed. In another experiment, hamster pineal glands were collected from animals killed either late in the light period (19.00 h) or in the latter half of the dark period. Isoproterenol promoted NAT activity and melatonin production only in glands collected in the latter half of the dark phase.

show abstract

Characterization and measurement of [125I]iodopindolol binding in individual rat pineal glands: existence of a 24-h rhythm in β-adrenergic receptor density

Cited by 37 publications

References 15 publications

Diurnal Rhythmicity of Beta-1- and Beta-2-Adrenergic Receptors in Ovariectomized, Ovariectomized Estradiol-Treated and Proestrous Rats

Diurnal Rhythmicity of Beta-1- and Beta-2-Adrenergic Receptors in Ovariectomized, Ovariectomized Estradiol-Treated and Proestrous Rats

Age-Associated Reduction in Pineal Beta-Adrenergic Receptor Density Is Prevented by Life-Long Food Restriction in Rats

Stimulatory Effect of Isoproterenol but Not of Dibutyryl Cyclic AMP on N-Acetyltransferase Activity and Melatonin Content of Syrian Hamster Pineal Gland in Organ Culture

Contact Info

Product

Resources

About