摘要:

Welsh MG. Current methodologies for the study of pineal morphophysiology. J Pineal Res 1994; 16: 113–120.AbstractLight and electron microscopes, with or without the use of immunohistochemical techniques, have been the instruments of choice for study of the pineal complex even up to recent times. Other morphological technologies have become available during the past decade that, if applied to current questions concerning pineal morphophysiology, could add considerably to our understanding of this complex system. Those technologies discussed include confocal scanning laser microscopy (in conjunction with other techniques including immunohistochemistry and three‐dimensional reconstruction), tissue culture methodologies, carbocyanine dyes (i. e., DiI), in situ hybridization, and application of microinjection methodologies. It is suggested that these technologies will be necessary for morphophysiolo‐gists to not only collaborate with molecular biologists and biochemists who study the pineal complex, but to corroborate the molecular and biochemical results of our colle

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00090.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Tedesco SC, Morton DJ, Reiter RJ. Hydroxyindole‐O‐methyltransferase activity in the pineal gland of the muskox (Ovibos moschatus). J. Pineal Res. 1994: 16: 121–126.AbstractCharacteristics of hydroxyindole‐O‐methyltransferase (HIOMT) activity were examined in pineal gland tissue from 10 muskoxen shot by native hunters in November, 1990. The enzyme preferentially methylated N‐acetylserotonin, with other hydroxyindole compounds showing relatively low affinities; activity peaked sharply at pH 8. 2. HIOMT was noncompetitively inhibited by its substrate, N‐acetylserotonin, and competitively inhibited by its product S‐adenosylhomocysteine. The catalytic mechanism appeared to be ordered as described in previous studies: S‐adenosylmethionine was the obligatory first substrate, followed by N‐acetylserotonin; methyl transfer then occurred and the products, melatonin and S‐adenosylhomocysteine, were released sequentially. Interestingly, the inhibition constant (K) for N‐acetylserotonin was relatively close to the Michaelis‐Menten constant (Km), which might allow physiological concentrations of N‐acetylserotonin to inhibit HIOMT activity in vivo. This effect could be relevant to the ecology of free‐living muskoxen during the dramatic seasonal fluctuations in dietary protein and daily photoperiod associa

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00091.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Koller M, Harma M, Laitinen JT, Kundi M, Piegler B, Haider M. Different patterns of light exposure in relation to melatonin and Cortisol rhythms and sleep of night workers. J. Pineal Res. 1994: 16: 127–135.AbstractThere is strong evidence to suggest that circadian psychophysiological adaptation processes are modified by light, depending on its intensity and timing. To characterize such modifications and determine whether they are associated with an alteration in the day/night pattern of melatonin excretion, measurements were obtained around the clock in 14 permanent night workers, each studied over a 48 hr period in the field. The light exposure behavior of these workers was studied with a newly developed light dosimetry by measuring light intensity at eye level. Physical activity was continuously registered and sleep indices were obtained by sleep logs and activity markings. Circadian rhythms of melatonin and Cortisol were analysed from salivary samples collected for 24 hr at 2 hr intervals. The inter individual variation of melatonin acrophase determined by cosinor analysis was greater than 180 degrees (from around midnight to noon) and that of Cortisol was about 135 degrees (from early morning to afternoon). Hormonal phase positions coincided significantly with light exposure: the more bright light pulses in the morning (maximum lux between 0600 and 0900), the less were the melatonin and Cortisol acrophases shifted into the day. There was also a negative correlation between melatonin acrophase shift and duration of the overall light exposure above 1500 lux. Morning light maximum and sleep onset correlated highly significantly. Night workers were divided into those with less than (‘non‐shifters’, n = 9) and more than 6 hr deviation from midnight (‘shifters’, n = 5) of the melatonin acrophase. The group comparison revealed a marked difference of the mean melatonin concentrations at night, and at 0700. Shifters did not experience bright light exposure in the morning and showed a tendency towards shorter overall exposure of light above 1500 lux. In conclusion, light avoidance behavior during morning hours, as observed in 5 out of 14 night workers, coincided significantly with a phase delay of melatonin acrophase. Light avoidance also correlated with an earlier sleep onset and a tendency to longer sleep hours. Thus our data suggest that the interaction of a phase shifted activity cycle and the light/dark exposure leads in the field situation to different degrees of adaptation to the prevailing activity/rest requirements, depending on dose and phase position of bright lig

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00092.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Yellon SM. Acute 60Hz magnetic field exposure effects on the nucleation rhythm in the pineal gland and circulation of the adult Djungarian hamster. J. Pineal Res. 1994; 16: 136–144.AbstractAdult male and female hamsters in long days (16 hr of light) were exposed to a 1 gauss 60 Hz magnetic field for 15 min starting 2 hr before lights off. Sham‐exposed controls were placed in an adjacent exposure system but current was not applied. Hamsters were decapitated at 0.5–2 hr intervals from 1 hr before lights off to 1 hr after lights on (n =4–6/clocktime/group); sera were harvested and pineal glands obtained for melatonin radioimmunoassay. In controls, pineal melatonin significantly increased from an average daytime baseline of less than 0.3 ng/gland to 3 ng/gland by 3 hr after lights off (P<0.05, ANOVA). This increase was sustained for the duration of the night and returned to baseline within 1 hr after lights on. A similar melatonin rhythm was found in serum; concentrations ranged from 30 to 50 pg/ml at night and returned to a baseline of 12 pg/ml or less by 1 hr before lights on. The single magnetic field exposure reduced the duration and blunted the rise in the nocturnal melatonin rhythm. The study was then repeated in its entirety 6 months later. The same magnetic field treatment significantly suppressed pineal melatonin content at 5 hr after lights off and reduced serum melatonin concentrations at 3 and 5 hr after dark onset compared to sham‐exposed controls. Thus, the acute magnetic field exposure was again found to blunt the increase and suppress the duration of the nighttime melatonin rise. Point‐by‐point comparisons with the first study, however, did not replicate the magnetic field‐associated reduction in pineal melatonin content at 3 hr into the night, as well as in pineal and serum melatonin at 7. 5 hr after lights off. Concern about this divergence led us to repeat the experiment for a second time 6 months later. In both sham‐ and magnetic field‐exposed groups, melatonin increased within 3 hr after lights off and this rise was sustained until 0. 5 hr before lights on; nighttime melatonin content in the pineal gland was approximately 2 ng while in circulation melatonin concentrations averaged 60 pg/ml or less. No statistical differences were evident between the control and magnetic field exposed hamsters at any clocktime (P<0. 05, ANOVA). Thus the absence of an effect of magnetic field exposure on the melatonin rhythm in either the pineal gland or circulation in this second replicate study contrasts with the clear suppression of the nocturnal melatonin rhythm in two previous experiments. Further work is needed to define the parameters of magnetic field exposure that consistently affect the pineal gland and its circadian melatonin rhythm. The time of the year for experimentation, animal age, or the endogenous response to exposure may be variables that might be understood before the physiological importance of magnetic fields for circadian time keeping mechani

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00093.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Reiter RJ, Reiter MN, Hattori A, Yaga K, Herbert DC, Barlow‐Walden L. The pineal melatonin rhythm and its regulation by light in a subterranean rodent, the valley pocket gopher (Thomomys bottae). J. Pineal Res. 1994; 16: 145–153.AbstractThe daytime and nighttime levels of pineal N‐acetyltransferase (NAT) activity, hydroxyindole‐O‐methyltransferase (HIOMT) activity, and melatonin were measured in adult male and female valley pocket gophers,Thomomys bottae.This species was chosen for study because it is a subterranean rodent that inhabits burrows whose openings to the surface are closed. Therefore, under field conditions it is estimated that the pocket gopher spends roughly 99% of its time in absolute darkness in underground burrows. When wild captured pocket gophers were maintained under a light dark cycle (light intensity during the day of roughly 140 μ,W/cm2), nighttime levels of pineal NAT activity and melatonin content were higher than values measured during the day; on the other hand, HIOMT activity in the pineal gland was similar in the day and at night. When pocket gophers were exposed to an extended light period (220 μW/cm2) 4 hr into the night, the rise in melatonin synthesis normally associated with darkness onset was not inhibited. Also, when gophers were acutely exposed to a light intensity of 400 μW/cm2for 1 hr beginning 4 hr after darkness onset, neither high nocturnal levels of pineal NAT nor pineal melatonin contents were reduced. Finally, when pocket gophers were exposed to a 600 (μW/cm2light intensity at either 4 hr or 8 hr into the dark period, pineal melatonin synthesis remained elevated at a level comparable to that measured in dark‐exposed controls. The results show that under controlled laboratory conditions the pineal gland of the valley pocket gopher, a species that in its natural habitat spends about 99% of its time in absolute darkness, exhibits higher melatonin synthesis during night than during the day. While the rhythm in pineal melatonin production in the pocket gopher is clearly synchronized by the prevailing light: dark cycle, high nighttime pineal melatonin synthesis is not readily inhibited by light in the intensity range of 220 to 600μW/cm2. In terms of its relative insensitivity to light at night, the pineal gland of the valley pocket gopher resembles that of other diurnall

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00094.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Esquifino AI, Moreno ML, Steger RW. Effects of chronic melatonin administration or adrenal medulla catecholamine metabolism in adult male golden hamsters. J. Pineal Res. 1994; 16: 154–158.AbstractThe role of melatonin on adrenal medullary function was evaluated in adult golden (Syrian) hamsters injected daily at either 0800 or 1600 with melatonin (25 μxg/hamster) or vehicle (0. 1% ethanol in saline). Sixty days after initiation of treatment and 16 or 24 hr after the last injection of melatonin, animals were killed by decapitation and blood and tissue collected. Plasma prolactin levels were reduced by chronic administration of melatonin only when animals were treated at 1600. Tyrosine hydroxylase (TH) activity in the adrenal medulla was not changed by either morning or afternoon administration of melatonin. Phenylethanolamine‐N‐methyl transferase (PNMT) was changed by afternoon administration of melatonin. Morning and afternoon melatonin injections led to the reduction of both adrenal monoamine oxidase (MAO) and catechol‐O‐methyl transferase (COMT) activities although the afternoon injections led to a greater magnitude of change. Norepinephrine and epinephrine contents were significantly reduced by morning melatonin administration but were not changed by afternoon administration of the hormone. These data suggest that melatonin has direct and possibly indirect effects on adrenal medullary function in the hamster. However, further studies will be required to characterize the effects of melatonin on catecholamine synthesis and release and the physiological significance of the

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00095.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Rodriguez AB, Lea RW. Effect of pinealectomy upon the nonspecific immune response of the ring‐dove (Streptopelia risoria). J. Pineal Res. 1994; 16: 159–166.AbstractThe different stages of the phagocytic process by granulocytes of pinealectomized or sham‐pinealectomized ring doves (Streptopelia risoria)as well as hematological parameters (total white blood cells, smear, and total protein) and serum hormone levels (triiodothyronine (T3), thyroxine (T4), and corticosterone) were studied. A number of immunological parameters of the phagocytosis process, including adherence capacity, mobility rate, the phagocytosis capacity for inert particles and the digestion capacity of ingested material, were studied. Adult male ring doves were injected intravenously with either 0. 1 ml of normal sheep serum (NSS) or saline (SS). Blood samples were collected before injection, and 1 hr, 3 hr, 24 hr, and 4 days afterwards. The results indicate that pinealectomy produces a significant increase in the number of total white blood cells and total protein concentration in plasma in addition to altering different stages of the phagocytic process. During the immunization study, a decrease in the percentage of leukocytes and lymphocytes and an increase in the percentage of heterophils accompanied by an increase in the concentration of serum corticosterone were observed 3 hr following treatment. For the immunological parameters, adherence capacity and latex bead ingestion were increased 3 hr after NSS injection and the NBT reduction test 3 and 24 hr after NSS treatment. In addition, the administration of NSS produced a significant increase in serum T3and T4concentrations 4 days following injection. These results show that pinealectomy has a marked effect on both the number and function of immune

ISSN:0742-3098    

DOI:10.1111/j.1600-079X.1994.tb00096.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY