摘要:

We investigated the impact of an eating‐fasting cycle (E:F 4:20 h) on free‐running urinary electrolyte excretion rhythms in intact male and female rats as well as hypophysectomized and adrenalectomized male rats. Under constant illumination both rats with intact vision and blind rats showed free‐running rhythms. No differences in period were found between male and female rats, rats maintained under constant light and blind rats, and intact rats and either hypophysectomized or adrenalectomized rats. After the introduction of the EF schedule abrupt phase shifts occurred; the magnitude depended linearly on the phase angle difference with respect to the free‐running state and the mid‐time of food availability, except for sodium in hypophysectomized and adrenalectomized animals. Additional studies with blind male rats showed that after termination of the EF cycle the acrophases correlated reasonably well with the acrophases expected on the basis of forward extrapolation of the free‐running rhythm. These experiments show that the phase shifts observed during periodic feeding are caused by masking and that for sodium an intact pituitary‐adrenal system is required.

ISSN:0022-1945    

DOI:10.1080/09291018909360002

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Motor activity of lacertid lizards(Gallotia galloti)was continuously recorded through sensitive platforms during some days in LD and later for up to 20 days in LL. Light intensity was 4.6 μE.s‐1.m2, both during light period of LD and in LL and temperature was maintained constant (28°C ±0.5). The circadian periods, calculated through periodogram analysis, were less than 24 h except in two lizards (out of 8) having a period somewhat longer than 24 h. Ultradian frequencies, obtained by means of a Fast Fourier Transform, were calculated for two consecutive segments of 64 data points ("morning”; and “afternoon”;, respectively) of each lizard and day. The ultradian peaks mainly fell into two bands: 9–36 c/day (= 160–40 min. period range) and 45–90 c/day (32–16 min). In most of the animals, the mean power of the first band was significantly greater (p < 0.05) than that of the second one, both in “morning”; and “afternoon”; segments, but for two lizards the mean power of the second band was significantly greater also in both data segments. These results are compared with those obtained in previous analyses of ultradian bands in LD.

ISSN:0022-1945    

DOI:10.1080/09291018909360003

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A seasonal variation was observed in the mitogenic response of human tonsillar lymphocytes and in the percentages of each subset. We found that the responsiveness of lymphocytes to mitogens was high in summer and low in winter. The identification of lymphocyte subsets by using monoclonal antibodies indicated that the percentages of T4positive cells and T8positive cells increased in summer and decreased in winter. The most significant change was observed in the percentages of T8positive cells. The significant relationship between the mitogenesis and the percentages of T8positive cells was observed. These results indicated that the seasonal variation in lymphocyte mitogenesis might depend on the size of T8positive cells.

ISSN:0022-1945    

DOI:10.1080/09291018909360004

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Various schedules of brain lighting with a red‐light emitting diode (rLED, peak of emission at 700 nm) were repeated over periods of 2 weeks in order to assess the roles of retinal and encephalic photoreceptors and their neural interconnections in Japanese quail. The results in terms of gonadal growth showed: (1) illumination of the brains of birds held on an 8L:16D cycle (lights on at 1000 hr) for 4 additional hours was stimulatory if the 4 hrs of illumination began at the end of the standard photoperiod but not when it began 4 hrs before the onset of the standard photoperiod. However, in blinded birds, 4 hrs of brain lighting was inductive in both cases; (2) four hrs of additional illumination of the brain of hypothalamic deafferented birds was not stimulatory, but 8 hrs of such illumination was stimulatory The results in terms of the rhythm of locomotor activity showed: (1) sighted control birds synchronized their activity with the environmental 8L:16D cycle, whereas blinded and brain‐illuminated birds free‐ran with a long period; (2) birds that experienced brain lighting from 0600 hr had a free‐running component with an initial phase determined by the timing of brain lighting, except in the case of deafferented birds; (3) all deafferented birds were arrhythmic. These results suggest that (1) the encephalic photoreceptor is involved in gonadotropin‐releasing activity and in entrainment in a compensatory manner, (2) the circadian clock(s) is/are located outside the infundibular nuclear complex; (3) the neural interconnections between the photoreceptors and the circadian clock(s) are essential for complete entrainment and photoperiodic gonadal growth.

ISSN:0022-1945    

DOI:10.1080/09291018909360005

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Adult male blossomheaded parakeets were held under artificial long (22 h) and short (2 h) daily photoperiods for 45 days or 90 days at different phases of the annual gonadal cycle to investigate the influences of altered photoperiods on the behaviour of the adrenal medulla in these birds. Results of the quantitative estimation of epinephrine (E) and norepinephrine (NE), counting of the tinctorially differentiated E and NE cells and cytofluorescence of NE containing areas in the adrenal medulla, have indicated that adrenomedullary response to a particular light‐dark schedule is uniform throughout the reproductive cycle of the parakeet. It has been found that significant (P < 0.001) loss of NE occurs only after 45 days treatment of very short daily photoperiods (2 L: 22 D), but the adrenal medulla of the rest of the experimentally treated birds remains essentially similar to the chromaffin tissue of birds held parallely under natural photoperiods. The results indicate that long daily artificial darkness for 45 days duration may influence the behaviour of the adrenal medulla, but the short photoperiod‐induced depletion of NE from the adrenal medulla appears to be independent of the testicular functions in the blossomheaded parakeets.

ISSN:0022-1945    

DOI:10.1080/09291018909360006

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Untouched, sham operated, castrated or hemigonadectomized adult male rats were autopsied at 02.30, 08.00, 11.00, 16.00, 18.00 or 24.00 h. In both the hypothalamus and cerebellum, the acetylcholinesterase (AChE) activity and protein contents were determined. When enzyme activity was expressed as a function of organ weight, sham operation increased hypothalamic AChE activity (10.8 ± 0.4 nmol/min/mg wet tissue vs. control 7.3 ± 0.2, p < 0.01). When results were expressed as a function of protein contents, a decrease in AChE activity was observed both in the hypothalamus (114 ± 4.2 nmol/min/mg protein vs. control 160±5.9) and in the cerebellum (60 ± 1.9 vs. control 71 ±2.1). Both gonadectomy and unilateral gonadectomy decreased the enzymatic activity in both the hypothalamus and cerebellum when compared with the sham operated group. No significant differences were observed between castrated and hemicastrated animals. When the results were expressed as a function of protein contents, circadian changes in AchE activity, both in the hypothalamus and cerebellum, were observed. Sham operation did not abolish the changes, whereas both gonadectomy and hemigonadectomy almost did. Circadian variations were not observed when results were expressed as a function of weight. Our results support those authors who stress the need for expressing results both as a function of protein content and of organ weight. In the male, as in the female, the activity of the hypothalamic cholinergic system seems to present circadian variations. The cerebellum seems to show the same. The fact that both gonadectomy and hemigonadectomy modify the activity suggests the possibility that the rhythm depends, at least in part, on influences other than endocrine, arising from the gonads.

ISSN:0022-1945    

DOI:10.1080/09291018909360007

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The seasonal changes in the size of the receptive field for grooming reflexes induced by 24‐h photic and non‐photic cycles were determined. Thirteen adult male cats were used in two studies, one study with non‐photic factors present in the light phase of 24‐h light‐dark cycles, and the other study with 24‐h non‐photic cycles present in constant light. The two studies demonstrated that non‐photic cycles are essential and sufficient in controlling the size of the receptive field for grooming reflexes. Analysis of variance of the daily patterns of activity indicated that significant differences were present whenever the cycles were effective in changing the size of the receptive field. The main difference in the daily activity patterns was the temporal relationship between “morning”; and “evening”; peaks, and this relationship was discussed in terms of the internal coincidence model for photoperiodic induction.

ISSN:0022-1945    

DOI:10.1080/09291018909360008

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0022-1945    

DOI:10.1080/09291018909360001

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor