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Hibernation‐dependent Alterations in Hypothalamic Synaptic Markers
Author(s) -
Oeltgen Peter R.,
Sparks Larry D.,
Brown Stephen A.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.903.2
Subject(s) - serotonergic , serotonin , medicine , endocrinology , melatonin , hypothalamus , hibernation (computing) , pineal gland , biology , 5 ht receptor , chemistry , receptor , state (computer science) , algorithm , computer science
To examine the possible involvement of the pineal‐hypothalamic neuroaxis during hibernation, we determined serotonergic, dopaminergic and cholinergic synaptic markers in the hypothalamus of hibernating 13‐lined ground squirrels compared to summer‐active animals. We also determined the effect of the pineal gland products, melatonin and N‐acetyl‐serotonin, on serotonergic binding in the hypothalamus of four groups of 13‐lined ground squirrels: Summer‐active, winter‐hibernating, recently aroused, and summer‐induced hibernating animals. In winter‐hibernating animals, hypothalamic content of dopamine, 5‐ hydroxyindolacetic acid (5‐HIAA), and the turn over of serotonin were decreased. The serotonin content and the activities of cholinergic enzymes were increased during hibernation. Moreover, there was no difference in homovanillic acid content or in the total serotonergic type‐2 binding. The modest decrease in serotonin type‐1 binding in hibernating animals was not statistically significant. Melatonin had no displacement effect on serotonin type‐1 binding and little effect on serotonin type‐2 binding in any animal. Although serotonin type‐2 binding was unaffected by N‐acetyl‐serotonin, the effect on serotonin type‐1 binding was state dependent. In summer‐active 13‐lined ground squirrels, N‐acetyl‐serotonin significantly inhibited serotonin type‐1 binding, while the inhibition was more pronounced in hypothalami from hibernating animals. The data suggest that the pineal gland may modulate hypothalamic function via serotonergic receptors.