Effects of Neonatal Clomipramine Treatment on Locomotor Activity, Anxiety-Related Behavior and Serotonin Turnover in Syrian Hamsters

We sought to determine whether ambient temperature (Ta) affects gonadal function by altering the rate at which circadian rhythms entrain to short day lengths. Syrian hamsters were housed in cages where they received 14 h of light per day (“long days,” 14L) at 22°C. Hamsters were then transferred to cages to receive 10 h of light per day (“short days,” 10L) and kept at 5, 22, or 28°C or were maintained in 14L at 22°C. Body mass and estimated testis volume as well as duration of nocturnal locomotor activity (α), previously established as a reliable indicator of the duration of nocturnal melatonin secretion, were determined over the course of 24 wk. Testicular regression in short days was accelerated by 4 wk at 5°C and delayed by 3 wk at 28°C relative to 22°C. The interval between α-expansion and initiation of testicular regression was markedly affected by Ta with delays of 0, 3, and 6 wk at 5, 22, and 28°C, respectively. All hamsters held at 5 and 22°C underwent testicular regression, but 25% of those maintained at 28°C failed to do so. We suggest that Ta modulates testicular regression primarily by affecting responsiveness of neuroendocrine target tissues to long melatonin signals.

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Sexual Behavior Induction of c-Fos in the Nucleus Accumbens and Amphetamine-Stimulated Locomotor Activity Are Sensitized by Previous Sexual Experience in Female Syrian Hamsters

Journal of Neuroscience ◽

10.1523/jneurosci.21-06-02123.2001 ◽

2001 ◽

Vol 21 (6) ◽

pp. 2123-2130 ◽

Cited By ~ 61

Author(s):

Katherine C. Bradley ◽

Robert L. Meisel

Keyword(s):

Sexual Behavior ◽

Locomotor Activity ◽

Nucleus Accumbens ◽

Sexual Experience ◽

Syrian Hamsters

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Binocular Interactions in the Entrainment and Phase Shifting of Locomotor Activity Rhythms in Syrian Hamsters

Journal of Biological Rhythms ◽

10.1177/0748730404272967 ◽

2005 ◽

Vol 20 (1) ◽

pp. 49-59 ◽

Cited By ~ 3

Author(s):

Jin Ho Park ◽

Matthew J. Paul ◽

Matthew P. Butler ◽

Irving Zucker

Keyword(s):

Locomotor Activity ◽

Phase Shifting ◽

Syrian Hamsters ◽

Activity Rhythms ◽

Binocular Interactions

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Neonatal clomipramine treatment of Syrian hamsters: effect on the circadian system

European Journal of Pharmacology ◽

10.1016/s0014-2999(98)00208-8 ◽

1998 ◽

Vol 349 (2-3) ◽

pp. 143-150 ◽

Cited By ~ 7

Author(s):

Paola C Yannielli ◽

Rodolfo A Cutrera ◽

Daniel P Cardinali ◽

Diego A Golombek

Keyword(s):

Circadian System ◽

Syrian Hamsters ◽

Clomipramine Treatment

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Effects of bright light on age-related changes in the locomotor activity of Syrian hamsters

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1998.274.3.r830 ◽

1998 ◽

Vol 274 (3) ◽

pp. R830-R839 ◽

Cited By ~ 7

Author(s):

Susan E. Labyak ◽

Fred W. Turek ◽

Edward P. Wallen ◽

Phyllis C. Zee

Keyword(s):

Locomotor Activity ◽

Daily Activity ◽

Activity Rhythm ◽

Bright Light ◽

Light Signal ◽

Light Cycle ◽

Middle Aged ◽

Syrian Hamsters ◽

Age Related ◽

Age Related Changes

Syrian hamsters display age-related changes in the expression of circadian rhythms and in responsiveness of the circadian system to photic and nonphotic stimuli. This study characterized the effects of age on the locomotor activity rhythm of middle-aged and old hamsters and evaluated the effects of strengthening the entraining light signal. Compared with young (4.5 mo) animals, middle-aged (11.25 mo) and old (16 mo) animals displayed increased daily bouts of activity ( P < 0.001) and reduced total daily activity and activity rhythm amplitude ( P < 0.05) in 14:10-h light-dark cycles. After the light intensity was increased from 300 to 1,500 lx during the light cycle, middle-aged hamsters demonstrated decreased daily activity bouts ( P < 0.05) and increased total daily activity ( P ≤ 0.01) and activity rhythm amplitude ( P≤ 0.001) compared with controls maintained in 300 lx. The pattern of changes in the activity rhythm of old experimental animals was similar to trends observed in middle-aged experimental hamsters, although not as robust. Thus age-related changes in the activity rhythm are occurring by middle age in hamsters, and the provision of stronger entraining signals may lead to more stable circadian organization.

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