Circadian rhythmicity in the nervous system of the cockroach, Periplaneta americana

Diurnal rhythmicity of nervous activity in Periplaneta americana was investigated, using acetylcholine (ACh) content, acetylcholinesterase (AChE) and spontaneous electrical activities as indices. AChE and electrical activities were maximum at 0 hr and minimum at 12 hr, while ACh showed an opposite rhythm. Central nervous system extract from cockroaches at 12 hr elevated the electrical activity while 0 hr-extract exerted inhibition. Lower concentrations of ACh had an elevatory influence while higher concentrations inhibited the electrical activity. A hypothesis is proposed, suggesting synthetic and releasing phases of ACh in a regular diurnal cycle, to explain the results obtained.     

Diurnal rhythm of drinking activity in the house musk shrew]

A diurnal rhythm of drinking activity in 7 male and 6 female house musk shrews (Jic: SUN) aged about one year was observed over a period of 10 days under a schedule of 12 hr light and 12 hr darkness (light on at 07:00). In general, the pattern of drinking activity was similar among both sexes, with around 24-hr diurnal rhythm. A few typical drinking patterns of these animals were represented as follows: 1) Drinking interval was very close in the dark phase, while it was a little too sparse in the light phase (n = 4). 2) Its interval remains stationary through a whole day (n = 5). 3) Drinking was performed between the latter half of light and the first half of dark phases (n = 4).     

Development of diurnal rhythm in some metabolic parameters in foals

1. The development of diurnal rhythm activity of FDPA, AspAT and A1AT and in levels of cortisol, T3 and T4 was observed in the blood serum of six foals. 2. The studies began when a foal was 7 days old and were repeated every month until foals reached 1 year of age. Blood samples were taken every 4 hr for one day each month. 3. As a control group four barren mares were used, kept and examined in the same conditions. 4. In mature mares, diurnal rhythms in activity of A1AT (acrophase at 2200 hr), AspAt (2400 hr) and cortisol (0630 hr) but in T3 only in summer months (acrophase at 0100 hr) were observed. 5. During the first 6 months of foal life, significantly higher mean levels of FDPA, A1AT, T3 and T4 than in control mares were found. 6. The cortisol level in foals was half as much as that of mature mares throughout the year. 7. In foals the diurnal rhythm in A1AT activity occurred in the 5th month and in AspAt--in the 12th month (acrophase at 2400 hr), but in cortisol levels it was developed already in the second month of foal life (acrophase at 0830 hr).     

Ontogeny of DNA synthetic rhythms in chick (Gallus domesticus) liver.

1. The diurnal pattern of DNA synthesis and mitotic activity in neonatal (1-4-day-old) chick liver were investigated under various feeding and lighting regimens. 2. In the meal-fed chicks under the condition of light-dark cycle, DNA synthesis exhibited a 12 hr cycle; the peaks occurring at 9:00 and 21:00. 3. Fasting caused a gradual decrease in the 21:00 peaks. 4. The changes in the lighting regimen to 24 hr continuous lighting also caused a profound change in the DNA-synthetic pattern, suggesting a complex interplay of feeding and lighting regimens in the manifestation of the DNA-synthetic rhythm in neonatal chick liver.     

Characterization of acetylcholinesterase molecular forms in slow and fast muscle of rat

Multiple molecular forms of acetylcholinesterase (AChE EC 3.1.1.7) from fast and slow muscle of rat were examined by velocity sedimentation. The fast extensor digitorum longus muscle (EDL) hydrolyzed acetylcholine at a rate of 110 mumol/g wet weight/hr and possessed three molecular forms with apparent sedimentation coefficients of 4S, 10S, and 16S which contribute about 50, 35, and 15% of the AChE activity. The slow soleus muscle hydrolyzed acetylcholine at a rate of 55 mumol/g wet weight/hr and has a 4S, 10S, 12S, and 16S form which contribute 22, 18, 34, and 26% of AChE activity, respectively. A single band of AChE activity was observed when a 1M NaCl extract with CsCl (0.38 g/ml) was centrifuged to equilibrium. Peak AChE activity from EDL and SOL extracts were found at 1.29 g/ml. Resedimentation of peak activity from CsCl gradients resulted in all molecular forms previously found in both muscles. Addition of a protease inhibitor phenylmethylsulfonyl chloride did not change the pattern of distribution. The 4S form of both muscles was extracted with low ionic strength buffer while the 10S, 12S, and 16S forms required high ionic strength and detergent for efficient solubilization. All molecular forms of both muscles have an apparent Km of 2 x 10(-4) M, showed substrate inhibition, and were inhibited by BW284C51, a specific inhibitor of AChE. The difference between these muscles in regards to their AChE activity, as well as in the proportional distribution of molecular forms, may be correlated with sites of localization and differences in the contractile activity of these muscles.     

Circannual variation of intestinal cell proliferation in BDF1 male mice on three lighting regimens

BDF, male mice were studied over a 24-hr span in winter, spring, summer and fall. For three weeks prior to study, one-third of the animals were kept under a lighting regimen of 8 hr light alternating with 16 hr of darkness (LD 8:16), one-third on a lighting regimen of LD 12:12 and a remainder on a lighting regimen of LD 16:8. During each study, subgroups of animals on all three lighting regimens were killed at 4-hr intervals over a 24-hr span. Twenty minutes prior to being killed, the animals received 5yCi of [³Hthymidine/0.2 ml/20 gm of body weight intraperitoneally. The thymidine uptake in the DNA of the colon and of the small intestine were studied as an index of cell proliferation. A circadian rhythm in [³H]-thymiduie uptake in the colon was found and validated by cosinor analysis. This rhythm was similar in acrophase and amplitude in the animals kept on LD 8:16 and LD 12:12. Also in the mice on LD 16:8, there was a statistically significant circadian rhythm of ('HJ-thymidtne uptake in the DNA of the colon during all four seasons. The acrophases of this rhythm, however, varied widely suggesting free running. A circadian rhythm of pHJ-thymidine uptake in small intestine was less consistent. In animals on all three lighting regimens, however, a circannual variation of f'HJ-thymidine uptake in DNA in colon and small intestine was found with the highest uptake during summer. This study indicates that a lighting regimen of LD 16:8 does not reliably synchronize the circadian rhythm of [³H]-thymidine uptake in the colon. It further shows a circannual rhythm of this function in the colon and in the small intestine which persists under three lighting regimens (LD 8:16, 12:12 and 16:8) maintained for three to four weeks prior to being killed.     

Effect of thiopental sodium and barbitone sodium on the total acetylcholine content and acetylcholinesterase activity in the brain tissue of Arvicanthis niloticus

The total ACh content and AChE activity were determined 1 hr after the i.p. injection of different doses of thiopental sodium (5, 10 and 20 mg/ml/100 g body wt) and barbitone sodium (20, 40 and 80 mg/ml/100 g body wt). The effect of different time intervals (1 min, 10 min, 30 min, 1 hr, 2.5 hr, 5 hr, 8 hr, 12 hr, 24 hr and 48 hr) on the total ACh content and AChE activity was investigated after i.p. injection of 10 mg thiopental sodium and 40 mg barbitone sodium/ml/100 g body wt. Both thiopental sodium and barbitone sodium increased the total ACh content in the brain tissue of Arvicanthis niloticus. Both drugs inhibited the brain AChE activity. It is thought that the increase in the total ACh content in the brain tissue of Arvicanthis niloticus may be due to a decrease in the release of ACh from the neuronal tissue and a decrease in AChE activity.     

Circadian Rhythms and time Measurement in Locomotor Activity of the Scorpion Leiurus Quinquestriatus (Buthidae)

The circadian rhythms of locomotor activity of the scorpion Leiurus quinqueslriatus were examined under different light-dark cycles and in free-running conditions. The circadian rhythm is bimodal in LD 12:12 with alternating cycles of temperature (35°-25°C) with high intensity (1300 lux) or in LD 12: 12 with constant temperature 35° C with 300 lux. In LD 12:12 (1300 lux), in long or in short light spans with constant temperature, the bimodal pattern is slightly changed with the appearance of a third minor peak of activity. In free-running conditions, the bimodal rhythm of locomotor activity persists in DD with T about 24 hr, but in LL the rhythm becomes unimodal with T about 24 hr. Cosinor and power spectrum analysis showed the presence of more than one periodic component. It seems that there is a correlation between the range of light regimens, temperature, light intensity and the coincidence of these components. These components are independently entrained by the environmental light cycle. The mechanism of entrainment of components is discussed.     

Control of the circadian rhythm of locomotor activity in the house cricket

A detailed analysis was made of the locomotor activity of Acheta domesticus under conditions of 12 hr light and 12 hr darkness (LD 12 : 12) and of continuous darkness (DD). Under LD 12 : 12 it was found that there are three types of insects: (1) those beginning the period of increased locomotor activity immediately after darkness falls, (2) considerably before this time, and (3) considerably after this time. Under DD conditions the greater amount of the insects have a free-running rhythm shorter than 24 hr, while only a small percentage have a rhythm of more than 24 hr.Destruction of the neurosecretory cells of the pars intercerebralis by means of radio waves leads to the formation of hyperactivity and loss of locomotor activity rhythm when more than half of these cells are destroyed.Injection of reserpine into the insect's haemolymph with doses of 10 μg/g of body weight results in a reduction in locomotor activity and produces arrhythmicity for 2 to 3 days under LD 12 : 12 conditions. Under DD conditions, however, this same dose results in a total and irretrievable loss of free-running rhythm. Histological studies of the brain of crickets following injection of reserpine show a large degree of accumulation of neurosecretion in the cells of the pars intercerebralis as compared with control insects.A hypothesis is put forward as to the way in which the brain centres regulating locomotor rhythm act in crickets.     

Circannual Variation of Intestinal Cell Proliferation in Bdf1 Male Mice on Three Lighting Regimens

BDF, male mice were studied over a 24-hr span in winter, spring, summer and fall. For three weeks prior to study, one-third of the animals were kept under a lighting regimen of 8 hr light alternating with 16 hr of darkness (LD 8:16), one-third on a lighting regimen of LD 12:12 and a remainder on a lighting regimen of LD 16:8. During each study, subgroups of animals on all three lighting regimens were killed at 4-hr intervals over a 24-hr span. Twenty minutes prior to being killed, the animals received 5yCi of [³Hthymidine/0.2 ml/20 gm of body weight intraperitoneally. The thymidine uptake in the DNA of the colon and of the small intestine were studied as an index of cell proliferation. A circadian rhythm in [³H]-thymiduie uptake in the colon was found and validated by cosinor analysis. This rhythm was similar in acrophase and amplitude in the animals kept on LD 8:16 and LD 12:12. Also in the mice on LD 16:8, there was a statistically significant circadian rhythm of ('HJ-thymidtne uptake in the DNA of the colon during all four seasons. The acrophases of this rhythm, however, varied widely suggesting free running. A circadian rhythm of pHJ-thymidine uptake in small intestine was less consistent. In animals on all three lighting regimens, however, a circannual variation of f'HJ-thymidine uptake in DNA in colon and small intestine was found with the highest uptake during summer. This study indicates that a lighting regimen of LD 16:8 does not reliably synchronize the circadian rhythm of [³H]-thymidine uptake in the colon. It further shows a circannual rhythm of this function in the colon and in the small intestine which persists under three lighting regimens (LD 8:16, 12:12 and 16:8) maintained for three to four weeks prior to being killed.     

Higher environmental temperature-induced change in synaptosomal acetylcholinesterase activity of brain regions

Expcsure of adult male albino rats to higher environmental temperature (HET) at 35° for 2–12 hr or at 45° for 1–2 hr increases hypothalamic synaptosomal acetylcholinesterase (AChE) activity. Synaptosomal AChE activity in cerebral cortex of rats exposed to 35° for 12 hr and in cerebral cortex and pons-medulla of rats exposed to 45° for 1–2 hr are also activated. AChE activity of synaptosomes prepared from normal rat brain regions incubated in-vitro at 39° or 41° for 0.5 hr increases significantly in cerebral cortex and hypothalamus. The activation of AChE in ponsmedulla is also observed when this brain region is incubated at 41° for 0.5 hr. Increase of (a) the duration of incubation at 41° and (b) the incubation temperature to 43° under in-vitro condition decreases the synaptosomal AChE activity. Lioneweaver-Burk plots indicate that (a) in-vivo and invitro HET-induced increases of brain regional synaptosomal AChE activity are coupled with an increase ofV _max without any change inK _m (b) very high temperature (43° under in-vitro condition) causes a decrease inV _max with an increase inK _m of AChE activity irrespective of brain regions. Arrhenius plots show that there is a decrease in transition temperature in hypothalamus of rats exposed to either 35° or 45°; whereas such a decrease in transition temperature of the pons-medulla and cerebral cortex regions are observed only after exposure to 45°. These results suggests that heat exposure increases the lipid fluidity of synaptosomal membrane depending on the brain region which may expose the catalytic site of the enzyme (AChE) and hence activate the synaptosomal membrane bound AChE activity in brain regions. Further the in-vitro higher temperature (43°C)-induced inhibition of synaptosomal AChE activity irrespective of brain regions may be the cause iof partial proteolysis/disaggregation of AChE oligomers and/or solubilization of this membrane-bound enzyme.To whom to address reprint requests:     

Cercal sensory regulation of acetylcholinesterase in nervous system of the cockroach, Periplaneta americana

Cercal ablation caused a significant loss in acetylcholinesterase (AChE) activity of the cercal nerves and terminal ganglion within 12 hr while a similar reduction in enzyme activity of connectives was noticed at least one day after cercectomy. The decrease in AChE activity of the nervous tissues showed a recovery toward control levels from 20 days of unilateral cercectomy whereas the bilateral cercectomy produced a continuous and irreversible decline in enzyme activity. These localized changes in AChE activity of the abdominal nervous system of the cockroach were attributed to be regulated by the cercal sensory innervation.     

Rhythmic cortisol secretion in the equine: Analysis and physiological mechanisms

Abstract

Four Thoroughbred mares (no. 1–4) were maintained under constant temperature (24°C) and controlled light (L/D:12/12 with lights on at 06.00 hr) conditions. They were fed and watered ad libitum with fresh feed and water given at 09.00 hr. After a 45‐day pre‐conditioning period, blood samples were obtained by veinipuncture at 4‐hr intervals for 14 days to determine circadian and day‐to‐day variation. The horses exhibited a circadian rhythm with maximum values attained at about 12.00 hr, however, there are periods of days in which no rhythm is distinguishable. Ultradian rhythms with mean periods of 105 to 128 and 24 to 31 min are superimposed upon the circadian rhythm. The individual rhythms are quite variable from horse to horse and within the same horse. During periods of decline in plasma cortisol with metabolic half‐lives of approximately 70 min, secretion of cortisol was very low or had ceased. During periods of increasing plasma concentration, secretion was occurring at a faster rate than degradation. Rapid decreases in plasma concentration (metabolic half‐life of approximately 30 min) was accompanied by a rise in specific activity indicating cortisol with a high specific activity was entering the plasma pool from other storage pools.     

Influence of pregnancy on diurnal and seasonal changes in cortisol, T3 and T4 levels in the mare blood serum.

1. The diurnal changes in the level of total protein, cortisol, T3 and T4 were studied in four barren and four pregnant standard-bred mares, kept and examined under the same conditions. 2. Blood samples were taken every 4 hr. for one day each month, throughout one year. 3. In barren mares, a diurnal rhythm in cortisol level (acrophase at 0530 hr in summer and at 0830 hr in winter) and in T3 level (acrophase at 1330 hr in summer and at 1800 hr in winter) was found. 4. In pregnant mares, a diurnal rhythm in cortisol level only till 5th month of pregnancy was observed. 5. A diurnal rhythm in T3 level was found throughout the pregnancy, with acrophase always at 1400 hr. 6. No diurnal rhythm in the total protein content and in the T4 level was observed. 7. In both groups of mares the seasonal cyclicity in T3 and T4 levels were found. A seasonal cyclicity in cortisol level was found only in pregnant mares. 8. Pregnancy abolished seasonal cyclicity in total protein and showed it in cortisol level. 9. Pregnancy in mares modifies diurnal rhythms as well as seasonal cycles in secretion and metabolism of the hormones studied.     

Ultrastructural localization of acetylcholinesterase in cultured cells. III. DFP treated embryo muscle

Brief treatment with 10(-4)M diisopropylfluorophosphate (DEP) irreversibly inactivates acetylcholinesterase (E.C.3.1.1.7; acetylcholine hydrolase) (AChE) activity in 10 day old chick embryonic muscle cultures. Electron microscopic cytochemistry was employed to follow the distribution of new AChE during recovery from DEP treatment. In normal 10 day cultures of embryo pectoralis muscles AChE is localized in the nuclear envelope, perinuclear sarcoplasm, sarcotubular system, subsurface vesicles and bound outside the cells. Immediately after DFP treatment AChE activity is absent in large myotubes. Within 15 min, activity is randomly present in small amounts in the sarcotubular system and nuclear envelope. There is a dramatic increase in activitv in the nuclear envelope during the 1st hr of recovery, and connections between the nuclear envelope and sarcotubular system are often seen. The next few hr of recovery show increased AChE activity. By 4 hr activity approaches that of controls. Six to 8 hr after treatment, AChE activity can be detected spectrophotometrically in the medium and can be seen bound outside the cells with the electron microscope. The spatial and temporal patterns of AChE activity demonstrate that the recovery of AChE and its mobilization and release from DFP-treated cells are not governed solely by the levels attained by the enzyme in the cultured embryo muscle.     

Regeneration of acetylcholinesterase in clonal neuroblastoma-glioma hybrid NG108-15 cells after soman inhibition: effect of glycyl-l-glutamine

Acetylcholinesterase (AChE) in the clonal NG108-15 cell line has been previously characterized. This cell line represents an in vitro system to study AChE regulation and effects of chemical compounds that may alter AChE activity. Recently, glycyl-L-glutamine (GLG) was demonstrated to function as a neurotrophic factor for maintenance of AChE content in cat denervated superior cervical ganglion cells. In the present study, regeneration of AChE activity in cultures of undifferentiated NG108-15 cells after soman inhibition was investigated in the presence and absence of GLG. Cells were treated with soman (5.5 × 10^–6 M) for 15 min and then washed to remove excess soman. Culture medium containing either GLG (10^–6, 10^–5, or 10^–4M) or glycyl-L-glutamic acid (10^–6 M) was added to cultures after soman treatment and remained in the medium until cell harvest. Cells were physically detached at various times after soman treatment and specific AChE activity was determined. After soman, AChE activity dramatically decreased to less than 1% of untreated cellular activity at 1 hr. AChE activity gradully increased after 5 hr, while untreated cell AChE activity was regained 20 hr after soman. The t_1/2 for AChE regeneration was approximately 10 hr. GLG did not increase the rate of AChE regeneration after soman inhibition. These results indicate that GLG is not a directly acting neurotrophic factor for AChE synthesis in NG108-15 cells after chemical AChE inactivation.Abbreviations AChE acetylcholinesterase - NG108-15 cell neuroblastoma-glioma 108-15 cell - DMEM Dulbecco's modified Eagles minimal essential medium - FBS fetal bovine serum - GLGA glycyl-L-glutamic acid - L-GA L-glutamic acid - GLG glycyl-L-glutamine - GD soman The opinions or assertions contained herein are the private views of the authors and are not to be construed as reflecting the view of the Department of the Army or the Department of the Army or the Department of Defense.     

Diurnal variations in physiological activities in the garden snail,Cryptozona ligulata

Summary Acetylcholinesterase (AChE) activity in the central nervous system and foot muscle in the garden snail,Cryptozona ligulata, was maximum at 20.00 h and minimum at 08.00 h during the 24 h period of the day. The cyclic variation in acetylcholine (ACh) was out of phase with that of AChE. In the body fluid, ACh content showed a rhythm with maximum at 00.00 h and minimum at 12.00 h, with AChE activity being in phase with it.The rhythm of spontaneous electrical activity of the nervous system was in phase with that of AChE activity in tissues. Perfusion with body fluid collected from snails at 20.00 h elevated the spontaneous electrical activity, while body fluid collected at 08.00 h inhibited the activity. Perfusion with extract prepared from the central nervous tissue isolated at 08.00 h elevated the electrical activity, while the extract prepared from nervous tissue isolated at 20.00 h inhibited the activity. Perfusion with 10^–4 M acetylcholine chloride solution elevated the electrical activity.It is suggested that the synthesis and release of ACh occur in a regular diel cycle in tissues. These changes, among others, may be responsible for the observed diurnal rhythmicity in electrical activity in the snail.     

Unequal twice-daily, sustained-release theophylline dosing in chronic obstructive pulmonary disease

Three regimens of sustained-release theophylline (SRT), Theostat were administered to 12 male patients with chronic obstructive pulmonary disease in a randomized cross-over trial. Each 7-day treatment consisted of: treatment A--8 mg/kg at 0700 hr and 4 mg/kg at 1900 hr, treatment B--6 mg/kg at 0700 hr and 6 mg/kg at 1900 hr, treatment C--4 mg/kg at 0700 hr and 8 mg/kg at 1900 hr. Peak expiratory flow (PEF) was recorded each day at 0700, 1100, 1500, 1900 and 2300 hr and theophylline plasma levels were determined on the 7th day of each treatment sequence. Cosinor analysis of the data revealed significant circadian rhythms in PEF for each treatment: the mesor (24-hr average) was significantly higher with C and acrophases (phi, peak time of PEF rhythm) were located at 1426 hr for A and 1425 hr for C; a shift of the acrophase to an earlier timing was detected for B (phi = 0958 hr. These findings suggest that an unequal, twice-daily SRT dosing with the greater amount of drug at night may be beneficial in the treatment of COPD.     

Circadian rhythm resetting in sparrows: early response to doublet light pulses

Circadian responses were studied using the perching activity of house sparrows (Passer domesticus). The sparrows were subjected to single or double 4-hr light pulses (the single pulses or the second pulses of the doublets scanned 24 hr) in the first cycle after previous entrainment to a light-dark cycle (LD 12:12). The differences in times at which the birds commenced perch-hopping in LD 12:12 before the pulses and in the five cycles immediately following the pulses were determined (phase shifts). A 24-hr time profile for phase shifts in response to single light pulses replicated our previous study: Early-night pulses delayed the rhythm (-1.7 hr), while late-night pulses advanced the rhythm (+3.8 hr). After pretreatment with a light pulse that advanced the birds +2.7 hr, the resetting curve was advanced. There were no delays; the range of average shifts was +0.1 hr to +6.2 hr. After pretreatment with a light pulse that delayed the birds -1.7 hr, the resetting curve was delayed. Average delays as much as -1.1 hr and advances up to +2.1 hr were measured. The data for double pulses were interpreted from predictions made from single-pulse data.     

Effects of the organophosphate insecticides diazinon and parathion on bobwhite quail embryos: skeletal defects and acetylcholinesterase activity

Bobwhite quail eggs were injected at 48 or 72 hr of incubation with various doses of the organophosphate (OP) insecticides diazinon or parathion and the embryos were examined after an additional 48 hr of incubation by both histological and cartilage-staining methods. Bobwhite embryos did not display the notochordal folding or vascular enlargement reported for OP-injected chicken embryos. Cartilage staining of embryos injected with insecticide at 72 hr of incubation and recovered at day 12 of incubation revealed severe shortening and contortion of the vertebral axis, as well as tibiotarsal, rib, and sternum defects. Parathion was more potent in causing skeletal defects than diazinon. No type I defects (micromelia, parrot beak) were detected. Radiometric acetylcholinesterase (AChE) assays of whole embryo homogenates were performed for day 6, 9, and 12 diazinon-injected and control embryos. Diazinon effected drastic reductions in AChE activity. Although the AChE and axial skeletal responses of bobwhite embryos to OP injection are similar to those reported in the literature for other species, some major differences in the bobwhite response were noted: namely, the absence of notochordal folding in the young bobwhite embryo and the absence of type I defects at day 12. These differences suggest that further studies with the bobwhite quail would be useful in clarifying the mechanisms involved in OP-induced teratogenesis.