Comparative transcriptomics of the Djungarian hamster hypothalamus during short photoperiod acclimation and spontaneous torpor

Activation of lipoprotein lipase (LPL) in brown fat of the Djungarian hamster ensures substrate supply for nonshivering thermogenesis. Cold acclimation [5 degrees C ambient temperature (Ta)] in long photoperiod [light-dark (LD) 16:8] increased brown fat LPL activity from 4.7 to 22.7 nmol oleate.mg-1.min-1 within 1 day. Slight reduction of this high LPL activity was observed during prolonged cold exposure for up to 4 wk. Deacclimation (transfer from 5 to 23 degrees C Ta) caused total inactivation of brown fat LPL within 4 days. Short photoperiod (LD 8:16) also stimulates brown fat LPL activity. Its effect can be summarized by three different observations. At thermoneutrality short photoperiod elevated LPL activity to 7.1 instead of 4.7 nmol.mg-1.min-1 observed in long photoperiod. Second, at low ambient temperature short photoperiod reinforces the effect of cold acclimation. Maximum LPL activity of cold-exposed Djungarian hamsters averaged 23.7 nmol.mg-1.min-1 in long photoperiod and was elevated to 35.5 nmol.mg-1.min-1 in short photoperiod. Third, inactivation of LPL during deacclimation was delayed in short photoperiod. These results demonstrate that photoperiod as well as ambient temperature may be cooperatively used as environmental cues for seasonal acclimation of brown fat substrate supply for nonshivering thermogenesis.

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Delayed Puberty in the Male Djungarian Hamster: Effect of Short Photoperiod or Melatonin Treatment on the GnRH Neuronal System

Neuroendocrinology ◽

10.1159/000125857 ◽

1991 ◽

Vol 54 (2) ◽

pp. 96-102 ◽

Cited By ~ 27

Author(s):

Kevin L. Buchanan ◽

Steven M. Yellon

Keyword(s):

Short Photoperiod ◽

Delayed Puberty ◽

Neuronal System ◽

Djungarian Hamster ◽

Melatonin Treatment

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Physiological doses of prolactin stimulate pelage pigmentation in Djungarian hamster

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1985.248.6.r664 ◽

1985 ◽

Vol 248 (6) ◽

pp. R664-R667 ◽

Cited By ~ 3

Author(s):

M. J. Duncan ◽

B. D. Goldman

Keyword(s):

Growth Hormone ◽

Predominantly White ◽

Short Photoperiod ◽

Dark Agouti ◽

Djungarian Hamster ◽

Melanocyte Stimulating Hormone ◽

Chronic Infusion ◽

Ovine Prolactin ◽

Stimulating Hormone

The Djungarian hamster exhibits a dark agouti pelage during the summer. Under the influence of decreased daylength, this species molts and develops a predominantly white winter coat. After a patch of white fur was plucked from hamsters housed in short photoperiod, chronic infusion of 10 or 20 micrograms ovine prolactin (o-PRL)/day led to the growth of a patch of pigmented fur, thus reversing the effect of the decreased daylength. Circulating o-PRL levels produced by the 10-micrograms/day infusions ranged from 17.9 +/- 4.0 to 35.1 +/- 13.8 (SE) ng/ml and thus approximated the endogenous circulating prolactin levels found in hamsters with the dark summer pelage (6, 9). Infusion of o-PRL stimulated pigmentation of the pelage of castrated as well as intact hamsters, suggesting that the testes do not mediate this effect. Infusion of ovine growth hormone (20 micrograms/day) did not stimulate pigmentation, and infusion of alpha-melanocyte-stimulating hormone (10 micrograms/day) gave inconclusive results.

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Hypothalamic NPY and prepro-NPY mRNA in Djungarian hamsters: effects of food deprivation and photoperiod

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.269.5.r1099 ◽

1995 ◽

Vol 269 (5) ◽

pp. R1099-R1106 ◽

Cited By ~ 19

Author(s):

J. G. Mercer ◽

C. B. Lawrence ◽

B. Beck ◽

A. Burlet ◽

T. Atkinson ◽

...

Keyword(s):

Gene Expression ◽

Body Weight ◽

Food Deprivation ◽

Arcuate Nucleus ◽

Short Photoperiod ◽

Published Data ◽

Djungarian Hamster ◽

Reduced Body ◽

Hypothalamic Arcuate Nucleus ◽

Long Photoperiod

Two catabolic states leading to loss of body weight were compared in the Djungarian hamster (Phodopus sungorus campbelli). Hypothalamic neuropeptide Y (NPY) and gene expression for NPY and corticotropin-releasing factor (CRF) were examined after withdrawal of food for 48 h or exposure to short photoperiod for 10 or 20 wk. Food deprivation was accompanied by increases in both NPY and prepro-NPY mRNA in the hypothalamic arcuate nucleus (ARC). Increases in gene expression were limited compared with published data from the rat and were inversely related to predeprivation body weight. Exposure to short photoperiod for 20 wk reduced body weight by 39%, but the activity of the NPY-ergic system was not affected; peptide concentration and gene expression were similar in short photoperiod hamsters and long photoperiod controls. The hypothalamic NPY-ergic system of the Djungarian hamster is sensitive to weight loss due to imposed manipulations of energy balance, but the catabolism observed in short photoperiod gives rise to a body weight that is appropriate to the season encoded by the photoperiod. CRF gene expression was not affected by food deprivation or short photoperiod.

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