Splitting of the locomotor activity rhythm in rats by exposure to continuous light

1983 ◽  
Vol 244 (4) ◽  
pp. R573-R576 ◽  
Author(s):  
Phyllis W. Cheung ◽  
Charles E. McCormack
Keyword(s):  
Locomotor Activity ◽  
Estrous Cycle ◽  
Activity Rhythm ◽  
Continuous Light ◽  
Female Rats ◽  
Locomotor Rhythm ◽  
Estrous Cycles ◽  
Locomotor Activity Rhythm ◽  
Active Portion ◽  
Free Running

Female rats exposed to low intensities (0.1–1.5 lx) of continuous light (LL), displayed regular estrous cycles and free-running circadian rhythms of locomotor activity. In most rats, as the intensity of LL was increased to >2.0 lx, components within the active portion (α) of the locomotor rhythm remained synchronized as the periodicity of the rhythm lengthened. However, in a few rats agr split into two components; one of which free-ran with a period shorter than 24 h, while the other free-ran with a period longer than 24 h. As soon as the two components became maximally separated they spontaneously rejoined. In most rats, estrous cycles ceased shortly after the intensity of LL was increased to >2.0 lx even though the locomotor activity rhythm retained its unsplit free-running nature. These observations suggest that the multiple oscillators that control the rhythms of locomotor activity and the estrous cycle are normally coupled to one another. In certain intensities of LL, these oscillators uncouple and free-run with different periodicities, a condition which causes estrous cycles to cease and sometimes produces a split locomotor activity rhythm. circadian rhythm; oscillators; estrous cycle Submitted on November 9, 1981 Accepted on October 11, 1982

CIRCADIAN LOCOMOTOR ACTIVITY AND ITS ENTRAINMENT BY FOOD IN THE CRAYFISH PROCAMBARUS CLARKI

1994 ◽  
Vol 190 (1) ◽  
pp. 9-21 ◽  
Author(s):  
F F De Miguel ◽  
H Aréchiga
Keyword(s):  
Locomotor Activity ◽  
Activity Rhythm ◽  
Food Reinforcement ◽  
Continuous Light ◽  
Food Delivery ◽  
Continuous Darkness ◽  
Locomotor Activity Rhythm ◽  
Activity Peak ◽  
Free Running ◽  
Two Peaks

The aim of our experiments has been to study the effect of light and food in the locomotor activity rhythm of the crayfish Procambarus clarki. Experiments were carried out under light:dark (LD) cycles of 12 h:12 h, under continuous darkness (DD) and under continuous light (LL). Under LD cycles, two peaks of activity were observed during the night phase of the cycle, while resting was characteristic of the day phase. Under DD or LL, it was possible to follow a free-running rhythm with a periodicity of 22.3±0.84 h in DD and 24.8±0.27 h in LL, typical of circadian rhythms of nocturnal species. A single delivery of food in the day phase of the LD cycle resulted in an outburst of locomotor activity that lasted for several hours. In the ensuing days, an activity peak appeared in phase with the time of food delivery. The food-related activity peak could be followed for up to 2 weeks without food reinforcement. Under DD and LL, food induced an activity rhythm in previously arrhythmic animals. Here the period was longer than 24 h in DD (26.2±0.12 h) and shorter in LL (22.5±0.46 h). Together, these results strongly suggest that light and food may play a role entraining a locomotor activity rhythm in crayfish.

The Effects of Low Temperature Upon the Locomotor Activity Rhythm of Talitrus Saltator (Montagu) (Crustacea: Amphipoda)

1972 ◽  
Vol 57 (2) ◽  
pp. 393-399
Author(s):  
P. K. BREGAZZI
Keyword(s):  
Locomotor Activity ◽  
Low Temperature ◽  
Mode Of Action ◽  
Activity Rhythm ◽  
Inhibitory Factor ◽  
Locomotor Rhythm ◽  
Locomotor Activity Rhythm ◽  
Complete Cessation ◽  
Maximum Delay ◽  
Talitrus Saltator

1. Chilling Talitrus causes a complete cessation of locomotor activity and a delay in the appearance of successive activity peaks following return to normal temperatures. Maximum delay occurs if chilling begins during inactivity and is about equal to the duration of the chill. At other times the delay is less than the duration of the chill. 2. It is postulated that an inhibitory factor is concerned in the control of the locomotor rhythm of Talitrus, and a model is proposed to describe its possible mode of action.

scholarly journals The Effect of Perturbations in the Environmental Cycle of the Diurnal Rhythm of Activity of Periplaneta Americana L

1960 ◽  
Vol 37 (1) ◽  
pp. 154-163 ◽  
Author(s):  
JANET E. HARKER
Keyword(s):  
Locomotor Activity ◽  
Periplaneta Americana ◽  
Activity Rhythm ◽  
Neurosecretory Cells ◽  
Secretory Phase ◽  
Locomotor Rhythm ◽  
Locomotor Activity Rhythm ◽  
Transient Activity ◽  
Subsequent Phase ◽  
Three Stages

1. The locomotor activity rhythm of Periplaneta americana in alternating light and darkness is described as consisting of six stages. 2. The effect on the suboesophageal ganglion neurosecretory cycle of a change from light to darkness at each stage of the locomotor rhythm is described, and three stages in the neurosecretory cycle are recognized. 3. The effect on an established locomotor activity rhythm of a change to darkness at various times of day is described in terms of the immediate reaction of the animal and of the subsequent phase relations of the rhythm. 4. The phases of the activity rhythm are not reset if the environmental change occurs during the active period. The final positioning of the phases, when the onset of darkness occurs during the non-secretory phase of the neurosecretory cycle, is dependent upon the subsequent light conditions; transient activity peaks may appear before the stable position is reached. 5. The dependence of the neurosecretory cells on some other centre for the provision of some secretory substance, or precursor, is discussed.

Environmental factors influencing the free-running period of locomotor activity rhythm in blinded rats

1987 ◽  
Vol 5 ◽  
pp. S134
Author(s):  
Kiyohisa Takahashi ◽  
Mizuo Takashima ◽  
Ken Ohi ◽  
Naoto Yamada ◽  
Kazutaka Shimoda
Keyword(s):  
Locomotor Activity ◽  
Environmental Factors ◽  
Activity Rhythm ◽  
Locomotor Activity Rhythm ◽  
Factors Influencing ◽  
Free Running ◽  
Free Running Period

scholarly journals Internal Factors Controlling the Suboesophageal Ganglion Neurosecretory Cycle in Periplaneta Americana L

1960 ◽  
Vol 37 (1) ◽  
pp. 164-170
Author(s):  
JANET E. HARKER
Keyword(s):  
Locomotor Activity ◽  
Room Temperature ◽  
Periplaneta Americana ◽  
Activity Rhythm ◽  
The Body ◽  
Suboesophageal Ganglion ◽  
Natural Conditions ◽  
Internal Factors ◽  
Locomotor Rhythm ◽  
Locomotor Activity Rhythm

1. Two interacting factors, both following a 24 hr. rhythm, are found to be concerned in the control of the locomotor activity rhythm of Periplaneta americana. 2. When the suboesophageal ganglion is chilled to 30°C., the rest of the body being kept at room temperature, the phases of the neurosecretory cycle are delayed for a period equivalent to the period of chilling. 3. A second cycle, which follows a 24 hr. rhythm, can act as a stimulus to the neurosecretory cycle if the latter is at a stage which responds to a stimulus. If the second cycle affects the neurosecretory cycle the phases of the latter are reset by the stimulus. The phases of the second cycle can be reset by a change from light to darkness while the suboesophageal ganglion is in the chilled state. It appears that the second cycle is immediately reset by the onset of darkness, regardless of the time at which this occurs. 5. The value to the animal, in its natural conditions, of the control of the locomotor rhythm by two interacting cycles is discussed.

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