EFFECTS OF SEX HORMONES AND ENVIRONMENTAL LIGHTING ON RAT HARDERIAN GLAND PORPHYRIN

1974 ◽  
Vol 63 (1) ◽  
pp. 99-102 ◽  
Author(s):  
RENÉE ULRICH ◽  
ARTHUR YUWILER ◽  
EDWARD GELLER ◽  
LENNART WETTERBERG
Keyword(s):  
Harderian Gland ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Constant Light ◽  
Constant Darkness ◽  
Intact Control ◽  
Gland Weight ◽  
Lighting Conditions ◽  
Harderian Glands ◽  
Environmental Lighting

SUMMARY Ovariectomy of adult female rats significantly decreased the porphyrin content of the Harderian glands compared with intact control rats. Treatment of ovariectomized rats for 5 days with testosterone propionate, progesterone or oestradiol did not alter porphyrin content or concentration; however, administration of oestradiol plus progesterone significantly increased Harderian gland porphyrin content to values indistinguishable from those of intact controls. Additionally, oestradiol treatment lowered the weight of the Harderian glands. Constant light or constant darkness for 35 days significantly decreased Harderian gland porphyrins compared with those of rats kept in diurnal lighting conditions. Constant light significantly lowered porphyrin values compared with those obtained from rats maintained in constant darkness. The effects of constant light were not altered by either ovariectomy or enucleation. Harderian gland weight was reduced in all groups kept in constant light.

OBSERVATIONS ON THE PINEAL GLAND, THE HARDERIAN GLANDS, THE RETINA, AND THE REPRODUCTIVE ORGANS OF ADULT FEMALE RATS EXPOSED TO CONTINUOUS LIGHT

1971 ◽  
Vol 51 (1) ◽  
pp. 117-125 ◽  
Author(s):  
R. J. REITER ◽  
D. C. KLEIN
Keyword(s):  
Adult Female ◽  
Light Exposure ◽  
Continuous Light ◽  
Harderian Gland ◽  
Female Rats ◽  
Constant Light ◽  
Continuous Illumination ◽  
Albino Rats ◽  
Surgical Removal ◽  
Harderian Glands

SUMMARY Harderian gland removal caused enlargement of the uteri of adult female albino rats which were maintained in 14 h light and 10 h darkness/day. Constant light exposure led to regression of the ovaries, adrenal glands and Harderian glands while the uteri exhibited a significant hypertrophic response. None of these changes were affected by surgical removal of the Harderian glands. The eyes and the retinas of albino rats maintained under continuous illumination underwent atrophic changes with the receptor cell elements of the retinas completely disappearing within 9½ weeks. Constant light obliterated the diurnal rhythm in the pineal enzyme, N-acetyltransferase. Neither the activity of pineal hydroxyindole-O-methyl-transferase nor the activity of pineal N-acetyltransferase were influenced by removal of the Harderian glands.

Effects of Changes in Environmental Lighting Upon Levels of Hydroxyindole O-Methyltransferase Activity in the Developing-Chick Pineal Gland

1975 ◽  
Vol 53 (4) ◽  
pp. 438-443 ◽  
Author(s):  
S. D. Wainwright
Keyword(s):  
Enzyme Activity ◽  
Pineal Gland ◽  
Diurnal Cycle ◽  
Enzymic Activity ◽  
Constant Light ◽  
Constant Darkness ◽  
Methyltransferase Activity ◽  
Constant Illumination ◽  
Lighting Conditions ◽  
Environmental Lighting

The level of hydroxyindole O-methyltransferase (HIOMT) activity in the pineal gland of developing chicks raised under constant illumination rose more rapidly and to higher values than in the gland of birds maintained in constant darkness. Rates of net increase in activity, and levels of activity attained, for birds raised under a diurnal cycle of illumination were intermediate between those maintained in constant light or darkness. Under each of the lighting conditions, the course of increase in enzymic activity was markedly affected by variations in an unidentified factor, the source of which appeared to be the hatching eggs.Birds transferred from constant light to the dark showed either an arrest of increase in enzyme activity or a loss of activity until the level equalled that observed for chicks of the same age raised in constant darkness. Chicks transferred from constant darkness to constant illumination showed marked increases in levels of enzyme activity at rates comparable with the maximal values observed with birds maintained under constant illumination, regardless of age and without delay. No diurnal cycle in level of HIOMT activity was observed in the pineals of 15-day birds.

EFFECTS OF PINEALECTOMY AND CONSTANT LIGHT AND DARKNESS ON PROLACTIN LEVELS IN THE PITUITARY AND PLASMA AND ON PITUITARY ULTRASTRUCTURE OF THE RAT

1972 ◽  
Vol 54 (2) ◽  
pp. 263-NP ◽  
Author(s):  
R. RELKIN ◽  
M. ADACHI ◽  
S. A. KAHAN
Keyword(s):  
Plasma Concentrations ◽  
Virgin Female ◽  
Female Rats ◽  
Constant Light ◽  
Constant Darkness ◽  
Plasma Prolactin ◽  
Continuous Darkness ◽  
Prolactin Content ◽  
Intermediate Degree ◽  
Pituitary Prolactin

SUMMARY The effects of constant light, constant darkness and diurnal lighting, in combination with pinealectomy or sham-pinealectomy, on pituitary and plasma concentrations of radioimmunoassayable prolactin were investigated in 8-week-old male and virgin female rats. Two to three days after operation random groups of pinealectomized and sham-pinealectomized animals of the same sex were placed together in either continous light, continuous darkness or diurnal light, and killed 21 days later. Compared with sham-operated diurnally-illuminated controls, constant darkness caused a decrease in pituitary prolactin content and a rise in plasma prolactin levels. Pinealectomy or constant illumination reversed the effect of constant darkness, resulting in an increase in pituitary prolactin content and a fall in plasma prolactin levels when compared with sham-operated diurnally-illuminated controls. Electron microscopy of lactotrophic cells of the sham-pinealectomized animals exposed to constant darkness revealed few cytoplasmic granules, whereas these cells in the sham-pinealectomized animals exposed to constant light contained abundant granules; compared with the former groups, lactotrophic cells of sham-pinealectomized rats exposed to diurnal lighting revealed an intermediate degree of granulation.

scholarly journals The Excitatory Effects of GABA within the Suprachiasmatic Nucleus: Regulation of Na-K-2Cl Cotransporters (NKCCs) by Environmental Lighting Conditions

2020 ◽  
Vol 35 (3) ◽  
pp. 275-286 ◽  
Author(s):  
John K. McNeill ◽  
James C. Walton ◽  
Vitaly Ryu ◽  
H. Elliott Albers
Keyword(s):  
Protein Expression ◽  
Suprachiasmatic Nucleus ◽  
Critical Role ◽  
Time Of Day ◽  
Adult Brain ◽  
Constant Darkness ◽  
Inhibitory Neurotransmitter ◽  
Lighting Conditions ◽  
Environmental Lighting ◽  
The Brain

The suprachiasmatic nucleus (SCN) contains a pacemaker that generates circadian rhythms and entrains them with the 24-h light-dark cycle (LD). The SCN is composed of 16,000 to 20,000 heterogeneous neurons in bilaterally paired nuclei. γ-amino butyric acid (GABA) is the primary neurochemical signal within the SCN and plays a key role in regulating circadian function. While GABA is the primary inhibitory neurotransmitter in the brain, there is now evidence that GABA can also exert excitatory effects in the adult brain. Cation chloride cotransporters determine the effects of GABA on chloride equilibrium, thereby determining whether GABA produces hyperpolarizing or depolarizing actions following activation of GABAA receptors. The activity of Na-K-2Cl cotransporter1 (NKCC1), the most prevalent chloride influx cotransporter isoform in the brain, plays a critical role in determining whether GABA has depolarizing effects. In the present study, we tested the hypothesis that NKCC1 protein expression in the SCN is regulated by environmental lighting and displays daily and circadian changes in the intact circadian system of the Syrian hamster. In hamsters housed in constant light (LL), the overall NKCC1 immunoreactivity (NKCC1-ir) in the SCN was significantly greater than in hamsters housed in LD or constant darkness (DD), although NKCC1 protein levels in the SCN were not different between hamsters housed in LD and DD. In hamsters housed in LD cycles, no differences in NKCC1-ir within the SCN were observed over the 24-h cycle. NKCC1 protein in the SCN was found to vary significantly over the circadian cycle in hamsters housed in free-running conditions. Overall, NKCC1 protein was greater in the ventral SCN than in the dorsal SCN, although no significant differences were observed across lighting conditions or time of day in either subregion. These data support the hypothesis that NKCC1 protein expression can be regulated by environmental lighting and circadian mechanisms within the SCN.

scholarly journals Transcriptional regulation of hydroxyindole O-methyltransferase in the chicken pineal gland: day/night changes and long-term effects of light and darkness

1993 ◽  
Vol 290 (3) ◽  
pp. 661-664 ◽  
Author(s):  
M Bernard ◽  
J Guerlotte ◽  
M Cogne ◽  
P Greve ◽  
J P Collin ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Gene Transcription ◽  
Cdna Probe ◽  
Constant Light ◽  
Constant Darkness ◽  
Mrna Levels ◽  
Long Term Effects ◽  
Night Time ◽  
Environmental Lighting ◽  
Time Fall

The indolic hormone melatonin is produced by the pineal gland according to a daily rhythm. The terminal step of melatonin synthesis is catalysed by hydroxyindole O-methyltransferase (HIOMT, EC 2.1.1.4). Adaptation to constant light or darkness modifies HIOMT activity and concentration. Using a cDNA probe encoding HIOMT, we investigated the effect of environmental lighting on HIOMT gene expression in the chicken pineal gland. HIOMT mRNA levels increased by 100% in constant light as compared with constant darkness. In addition, the present study disclosed the existence of a day/night rhythm of HIOMT gene transcription, with 3-fold higher mRNA levels at midday than at midnight. This transcriptional rhythm was not accompanied by day/night changes in HIOMT concentration, probably due to a slow turnover of this protein. Unexpected darkness did not prevent the daytime rise in HIOMT mRNA levels, whereas unexpected light prevented the night-time fall in HIOMT mRNA levels. Together, the data would suggest that the day/night rhythm of HIOMT gene transcription in the chicken pineal gland involves both a response to light and the activity of a biological oscillator.

CIRCADIAN RHYTHM OF PLASMA CORTICOSTEROID IN ADULT FEMALE RATS: CHRONOLOGICAL SHIFTS IN ABNORMAL LIGHTING REGIMENS AND CONNECTION WITH OESTROUS CYCLE

1975 ◽  
Vol 80 (3) ◽  
pp. 527-541 ◽  
Author(s):  
Yasuhiko Morimoto ◽  
Tatsuo Oishi ◽  
Kazutaka Arisue ◽  
Zensuke Ogawa ◽  
Fumiko Tanaka ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Adult Female ◽  
Female Rats ◽  
Constant Light ◽  
Constant Darkness ◽  
Vaginal Smear ◽  
Free Running ◽  
Normal Light ◽  
Lighting Regimen ◽  
Day By Day

ABSTRACT The circadian rhythm of plasma corticosteroid (CS) levels in adult female rats was studied chronologically under the following conditions: normal light-dark (LD), inverted light-dark (DL), constant dark (DD) and constant light (LL). Animals were accustomed to LD condition for 7 days before exposure to each abnormal lighting regimen. Normal circadian rhythm established under LD condition was clearly inverted on the third day of DL regimen, and the inverted rhythm persisted thereafter under DL condition. The circadian CS rhythm persisted essentially unchanged throughout DD condition, but lost its regular periodicity showing "free running" and changed day by day under LL condition. The average CS levels over a 24 h period were higher under LL than under DD condition. Plasma CS levels in each lighting regimen exhibited diurnal variations regardless of the vaginal smear patterns of autopsied animals. Exposure of rats to LL for 21 days made the circadian CS rhythm flat, but induced persistent oestrus in only a few animals. The data suggest that (1) an unexpectedly rapid inversion of the circadian CS rhythm occurs if animals are exposed to inverted light-dark environment; (2) constant darkness seems to be a near-natural environment for rats, and changes little of the pre-established circadian CS rhythm; (3) constant light, on the contrary, is assumed to be a stress for rats, and disrupts the circadian CS rhythm and elevates CS levels; (4) the change in circadian CS rhythm in adult female rats is not mediated by a change in gonadal function and the two conditions may not be connected directly with each other.

scholarly journals Morphological and Functional Changes of Pituitary GH and PRL Cells Following Prolonged Exposure of Female Rats to Constant Light

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Natasa Nestorovic ◽  
Natasa Ristic ◽  
Vladimir Ajdžanovic ◽  
Verica Milosevic
Keyword(s):  
Prolonged Exposure ◽  
Volume Density ◽  
Light Regime ◽  
Female Rats ◽  
Constant Light ◽  
Functional Changes ◽  
Pituitary Growth Hormone ◽  
Lighting Conditions ◽  
Female Wistar Rats ◽  
Cell Volumes

Abstract Light regulates numerous physiological functions including secretion of different hormones. Our aim was to determine morphological and functional changes of the pituitary growth hormone (GH) and prolactin (PRL) producing cells in female rats exposed to constant light regime from the peripubertal to adult period of life. Starting from the thirtieth postnatal day, female Wistar rats were exposed to constant light (600 lx) for the following 95 days. Controls were maintained under the regular laboratory lighting conditions. The GH and PRL cells were immunohistochemically visualized. Changes in cell volumes and volume densities were evaluated by stereology. Concentrations of PRL and GH in circulation were also determined. We detected significant decrease of the GH cell volume and volume density, followed by reduced the GH blood concentration in comparison to the controls. In contrast, PRL cells were larger in size and their volume density was significantly increased when compared to the controls. Accordingly, PRL concentration was elevated. It can be concluded that exposure of female rats to constant light regime, from peripubertal to adult period of life, causes inhibition of the pituitary GH and stimulation of PRL cells.

Changes in the characteristics of pulsatile luteinizing hormone secretion during the oestrous cycle and after ovariectomy and oestrogen treatment in female rats

1982 ◽  
Vol 94 (2) ◽  
pp. 177-182 ◽  
Author(s):  
Takashi Higuchi ◽  
Masazumi Kawakami
Keyword(s):  
Hormone Secretion ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Luteinizing Hormone Secretion ◽  
Oestrogen Treatment ◽  
Serum Lh ◽  
Lh Release

Changes in the characteristics of LH secretory pulses in female rats were determined in different hormonal conditions; during the oestrous cycle and after ovariectomy and oestrogen treatment. The frequency and amplitude of the LH pulses were stable during the oestrous cycle except at oestrus when a pattern could not be discerned because of low LH concentrations. These were significantly lower than those measured during other stages of the cycle. Mean LH concentrations and LH pulse amplitudes increased with time up to 30 days after ovariectomy. The frequency of the LH pulse was unchanged 4 days after ovariectomy when mean LH levels had already increased. The frequency increased 10 days after ovariectomy and then remained stable in spite of a further increase in mean serum LH concentrations. Oestradiol-17β injected into ovariectomized rats caused a decrease in LH pulse amplitude but no change in pulse frequency. One day after treatment with oestradiol benzoate no LH pulse was detectable, probably because the amplitude was too small. A generator of pulsatile LH release is postulated and an oestrogen effect on its function is discussed.

Gonadal hormones organize and modulate the circadian system of the rat

1981 ◽  
Vol 241 (1) ◽  
pp. R62-R66 ◽  
Author(s):  
H. E. Albers
Keyword(s):  
Testosterone Propionate ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Gonadal Hormones ◽  
Circadian System ◽  
Female Rats ◽  
Constant Darkness ◽  
Before And After ◽  
Free Running ◽  
Free Running Period

The circadian wheel-running rhythms of gonadectomized adult male, female, and perinatally androgenized female rats, maintained in constant darkness, were examined before and after implantation of Silastic capsules containing cholesterol (C) or estradiol-17 beta (E). The free-running period of the activity rhythm (tau) before capsule implantation tended to be shorter in animals exposed to perinatal androgen. Administration of C did not reliably alter tau in any group. E significantly shortened tau in 100% of females injected with oil on day 3 of life. In females, injected with 3.5 micrograms testosterone propionate on day 3, and males, E shortened or lengthened tau, with the direction and magnitude of this change in tau inversely related to the length of the individual's pretreatment tau. These data indicate that the presence of perinatal androgen does not eliminate the sensitivity of the circadian system of the rat to estrogen, since estrogen alters tau in a manner that depends on its pretreatment length.

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