The interaction of photoperiod and testosterone on the development of copulatory behavior in castrated male hamsters☆

Campbell, Constance S.; Finkelstein, Joel S.; Turek, Fred W.

doi:10.1016/0031-9384(78)90101-4

Cited by 82 publications

(37 citation statements)

References 21 publications

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“…For example, low doses of testosterone inhibit gonadotropin secretion in juveniles, but not in adults (Richardson, Gore, Venier, Romeo, & Sisk, 2001;Sisk & Turek, 1983) whereas doses of testosterone that activate reproductive behavior in adults fail to do so in juveniles (Meek, Romeo, Novak, & Sisk, 1997;Romeo et al, 2002). Exposure to short days generally reverts adults to the prepubertal state, i.e., high sensitivity to steroid negative feedback and low sensitivity to behavioral activation (Campbell, Finkelstein, & Turek, 1978;Ellis & Turek, 1979;Morin & Zucker, 1978). Interactions between testosterone and pubertal development on aggression have not been explored in this species.…”

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confidence: 99%

Testosterone, puberty, and the pattern of male aggression in Syrian hamsters

Romeo

Schulz

Nelson

et al. 2003

Developmental Psychobiology

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The interaction between testosterone and pubertal development on aggression in the male Syrian hamster (Mesocricetus auratus) was examined in two experiments. First, gonad-intact prepubertal and adult male hamsters were tested for aggression using the resident-intruder paradigm with an age-and weightmatched intruder. Prepubertal males engaged in a greater number of attacks and had longer attack durations than adults. In the second experiment, prepubertal and adult males were castrated and treated with either a 0-, 2.5-, or 5-mg pellet of testosterone, and their aggression was assessed using the resident-intruder paradigm. Prepubertal males again showed shorter attack latencies and greater attack durations compared to adult males across all levels of testosterone. Testosterone treatment did not significantly affect these behaviors before or after pubertal development. We conclude that (a) pubertal development is associated with a decline in aggression in the male Syrian hamster, and (b) a developmental shift in behavioral sensitivity or responsiveness to testosterone does not underlie the pubertal decrease in aggression. ß

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Testosterone, puberty, and the pattern of male aggression in Syrian hamsters

Romeo

Schulz

Nelson

et al. 2003

Developmental Psychobiology

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“…Photoperiod influences the effectiveness of intrahypothalamic testosterone (T) in activating the sexual behavior of birds and mammals [1,2], suggesting that the steroid sensi tivity of the brain is under environmental regulation. The male Syrian hamster has been used extensively as a mammalian model to study photoperiodic effects on the neuroendocrine system, because reproductive activity depends on a pineal mela tonin signal which is entrained to the ambient light/dark cycle Received: February 7, 1990 Accepted after revision: August 16, 1990 [3, 4].…”

Section: Introductionmentioning

confidence: 99%

“…There are changes in male copulatory, social behavior [6] and ultrasonic calling [7] which can be explained partly by the re duced circulating levels of androgen. However, short days also influence the behavioral sensitivity of castrated males to exoge nous T [2,8], Photoperiodic effects on behavioral responsive ness to androgens have been observed for locomotory behavior patterns. In other species (ring dove [I]) photo-inhibition re duces the responsiveness of the male to hypothalamic implants of T, suggesting that behavioral mechanisms are directly af fected by photoperiod.…”

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confidence: 99%

Brain Aromatization of Testosterone in the Male Syrian Hamster: Effects of Androgen and Photoperiod

Hutchison¹,

Hutchison²,

Steimer³

et al. 1991

Neuroendocrinology

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Estrogen formed by aromatization of testosterone (T) is involved in the activation of sexual behavior and control of the neuroendocrine system in the male Syrian hamster. Our study examined whether daylength influences formation of estrogen in the preoptic area (POA) and other neuroendocrine areas (anterior hypothalamus, AHT, and medial amygdala, MA) which are targets for T in behaviorally active males. Estrogen formation in individual brain samples was assayed in vitro using the stereospecific production of ³H₂O from (1β-³H) Tas a measurement of aromatase activity. Serum levels of PRL, LH, FSH and Twere compared with brain aromatase activity. Groups of intact, castrated and T-treated (chronic silastic T implants) male hamsters, previously selected on behavioral criteria as being sexually active, were maintained on long (16:8LD) or short (8:16LD) daylength for 16 weeks. Two further groups of males either intact or castrated and T-treated were shifted after 7 weeks from the long photoperiod to 12:12LD. POA, AHT and MA areas of sexually active males contained active aromatase systems which converted ³H-T to estrogens. Enzyme activity differed between the areas (POA, MA > AHT). Aromatase activity was low in medial septum and cerebral samples. Castration, which reduced serum T to undetectable levels and elevated LH and FSH, had no effect on preoptic aromatase activity. Although estrogen formation in POA did not differ between 8:16LD and 16:8LD males, castration reduced aromatase activity in AHT of both short- and long-day groups. Aromatase activity in AHT was also significantly reduced in photo-inhibited 12:12LD intact males. There was no analogous decrease in 5α-reductase or 17β-hydroxysteroid dehydrogenase (HSD) activity, indicating a specific effect on the aromatase. The effect of photoperiod on aromatase activity was not reversed by T treatment. Therefore, photoinhibition acts in part through the effects of reduced T levels on the anterior hypothalamus, but it also acts independently of circulating T Our results suggest that both androgen and photoperiod may regulate the AHT aromatase system and that this occurs by different mechanisms. The more active aromatase system in POA is insensitive to both castration and photoperiod. Behavioral deficits in short-day males are not due to changes in the preoptic aromatase system, but may be related to changes in aromatase activity within AHT. We conclude that there is a difference in the regulation of two locally active aromatase systems within the preoptic-anterior hypothalamic complex of the male hamster.

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“…Diminished responsiveness to rIL-1β in SD hamsters is reminiscent of the decline in behavioral sensitivity of male Syrian hamsters to androgens after adaptation to SD [23,54]. In Syrian hamsters, castration eliminates detectable circulating testosterone and terminates sexual behavior in the majority of individuals housed in LD [55].…”

Section: Discussionmentioning

confidence: 99%

“…In Syrian hamsters, castration eliminates detectable circulating testosterone and terminates sexual behavior in the majority of individuals housed in LD [55]. Likewise, several weeks of exposure to SD yields gonadal atrophy, substantial decreases in testosterone secretion, and marked reductions in copulatory behavior [23,54]. However, testosterone replacement therapy is significantly more effective in restoring copulatory behavior in castrates housed under LD as opposed to SD [23,56].…”

Section: Discussionmentioning

confidence: 99%

Photoperiodic regulation of behavioral responsiveness to proinflammatory cytokines

Wen

Prendergast

2007

Physiology & Behavior

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Symptoms of bacterial infection include decreases in body mass (cachexia), induction of depressivelike hedonic tone (anhedonia), decreases in food intake (anorexia), and increases in body temperature (fever). Recognition of bacteria by the innate immune system triggers the release of proinflammatory cytokines which induce these sickness behaviors via central and peripheral substrates. In Siberian hamsters, exposure to short day lengths decreases both the production of proinflammatory cytokines and the magnitude of the symptoms of infection. Short-day attenuation of sickness behaviors may arise solely from decreased production of cytokines; alternatively, substrates responsible for the generation of sickness behaviors may be less responsive to cytokines in short days. To discriminate among these hypotheses, Siberian hamsters were treated with either bacterial lipopolysaccharide (LPS; 25 μg) or recombinant mouse IL-1β (rIL-1β; 100 ng) following 11 weeks of exposure to long (15 h light/day) and short (9 h light/day) photoperiods. Replicating earlier work, the magnitude and/ or duration of LPS-induced anorexia, anhedonia, cachexia, and fever were greater in long-day relative to short-day hamsters. A comparable short-day attenuation of sickness behaviors and fever was obtained in response to rIL-1β treatment, despite treatment with identical concentrations of cytokine. These data suggest that hamsters subjected to immunoenhancing short days exhibit diminished symptoms of infection not solely because infections elicit lower levels of cytokine production, but also because the substrates upon which cytokines act become relatively refractory.

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The interaction of photoperiod and testosterone on the development of copulatory behavior in castrated male hamsters☆

Cited by 82 publications

References 21 publications

Testosterone, puberty, and the pattern of male aggression in Syrian hamsters

Testosterone, puberty, and the pattern of male aggression in Syrian hamsters

Brain Aromatization of Testosterone in the Male Syrian Hamster: Effects of Androgen and Photoperiod

Photoperiodic regulation of behavioral responsiveness to proinflammatory cytokines

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