Although these studies aren't very new, I just stumbled across them this evening and thought I would share in hopes this is educational and interesting for some of our other regulars.
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Distribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain.
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Despite a growing body of evidence that Vitamin D is involved in mammalian brain functioning, there has been a lack of direct evidence about its role in the human brain. This paper reports, for the first time, the distribution of the 1,25-dihydroxyvitamin D3 receptor (VDR), and 1alpha-hydroxylase (1alpha-OHase), the enzyme responsible for the formation of the active vitamin in the human brain. The receptor and the enzyme were found in both neurons and glial cells in a regional and layer-specific pattern. The VDR was restricted to the nucleus whilst 1alpha-OHase was distributed throughout the cytoplasm. The distribution of the VDR in human brain was strikingly similar to that reported in rodents. Many regions contained equivalent amounts of both the VDR and 1alpha-OHase, however the macrocellular cells within the nucleus basalis of Meynert (NBM) and the Purkinje cells in the cerebellum expressed 1alpha-OHase in the absence of VDR. The strongest immunohistochemical staining for both the receptor and enzyme was in the hypothalamus and in the large (presumably dopaminergic) neurons within the substantia nigra. The observed distribution of the VDR is consistent with the proposal that Vitamin D operates in a similar fashion to the known neurosteroids. The widespread distribution of 1alpha-OHase and the VDR suggests that Vitamin D may have autocrine/paracrine properties in the human brain.
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The
hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland (hypophysis). The hypothalamus, (from Greek ὑποθαλαμος = under the thalamus) is located below the thalamus, just above the brain stem. In the terminology of neuroanatomy, it forms the ventral part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is roughly the size of an almond.
The hypothalamus is responsible for certain metabolic processes and other activities of the Autonomic Nervous System. It synthesizes and secretes neurohormones, often called hypothalamic-releasing hormones, and these in turn stimulate or inhibit the secretion of pituitary hormones. The hypothalamus controls body temperature, hunger, thirst, fatigue, and circadian cycles.
JW: Not only does vitamin D appear to be a strong influence on hypothalamus function, but light itself directly influences this portion of the brain via signals generated and communicated from the optic nerve upon exposure. The strongest influence coming from that of blue light between a narrow spectrum that is a part of natural sunlight (I believe somewhere around 420 nm, which has been isolated and put to use in certain blue light therapy devices - like one that I own and use daily).
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The
substantia nigra is a brain structure located in the mesencephalon (midbrain) that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in dopaminergic neurons. The substantia nigra is part of the basal ganglia; the other parts of the basal ganglia include the striatum (caudate nucleus, putamen, and nucleus accumbens), globus pallidus, and subthalamic nucleus. Parkinson's disease is caused by the death of dopaminergic neurons in the substantia nigra pars compacta.
JW: The last sentence connects the dots as to why it has been proposed that vitamin D is important in the development and progression of Parkinson's.
Vitamin D receptor gene expression in human pituitary gland.
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1,25-dihydroxyvitamin D3 has important physiological effects such as calcium transport and cell growth and differentiation. These biological effects are mediated by their binding to specific intracellular receptor termed vitamin D receptor (VDR). VDR mRNA expression has been demonstrated in several tissues, but to date, there is no information about its presence in the human pituitary gland. In this report, we demonstrate VDR mRNA expression using the reverse transcription-polymerase chain reaction (RT-PCR), as well as the cellular expression of VDR by immunohistochemistry, both in the human pituitary gland. These results suggest the possibility that, like in the rat pituitary, VDR may regulate the human pituitary gene expression and hormone secretion.
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The
pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g (0.02 oz.). It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid bone in the middle cranial fossa at the base of the brain.
The pituitary gland secretes hormones regulating homeostasis, including tropic hormones that stimulate other endocrine glands. It is functionally connected to the hypothalamus by the median eminence.
The pituitary hormones help control some of the following body processes:
* Growth
* Blood pressure
* Some aspects of pregnancy and childbirth including stimulation of uterine contractions during childbirth
* Breast milk production
* Sex organ functions in both women and men
* Thyroid gland function
* The conversion of food into energy (metabolism)
* Water and osmolarity regulation in the body
* Secretes ADH (antidiuretic hormone) to control the absorption of water into the kidneys
* Temperature regulation
Vitamin D Prevents Cancer: Is It True?
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