Endocrine Abstracts

The vitamin A-derived hormone retinoic acid (RA) is best known for its essential role in development, but components of the RA signalling pathway are also expressed in regions of the adult brain, including the hypothalamus, which regulates feeding behaviour, metabolism and body weight. RA is synthesised by the tanycytes lining the third ventricle and has recently been found to regulate cell proliferation in the hypothalamus. Some animals, such as the hamster and F344 rat, alte...

For many animals anticipation of future changes in environmental conditions is a critical adaptation for survival. Seasonal changes in reproductive activity, body weight and adiposity, metabolism and coat condition are examples of such adaptive physiology. Clearly each of these involves neuroendocrine control. The environmental cue that triggers these changes is photoperiod, which is translated into the hormonal signal, melatonin, a product of the pineal gland. A considerable ...

Thyroid hormone (TH) regulation of hypothalamic function has been extensively investigated. It is driven, in part, by the presence of deiodinase enzymes in tanycytes surrounding the third ventricle converting T4 to active T3. Retinoic acid (RA), the transcriptionally active form of Vitamin A, has not previously been considered to be an important part of hypothalamic regulation. Data presented here highlights novel parallels between the TH and RA synthetic...