Zinc may help MSH production?

June 9, 2003

Hormonal Enzymes

*Zinc is involved in the activation, transportation, and regulation of

certain hormones of the pituitary, thyroid, thymus, adrenal, ovaries, and

testes. The hormone transporting enzyme, alpha-macroglobulin, and the protein,

albumin, often require zinc in order to transport its hormones. Epithelial

cells of the thymus gland produce the hormone, thymulin, which becomes active

only when bound to zinc. Thymulin is vital for the stimulation, maturation, and

differentiation of thymic lymphocytes (T-cells) that fight foreign and

infectious agents (Consolini R, 2000, Hadden JW, 1998). The pituitary

hormones, GH (growth hormone) and MSH (melanocyte stimulating hormone), and

IGF-I (insulin-like growth factor-I) depend on zinc in their roles involving

immunity, healing, and bone and muscle growth and development. IGF's are

hormone-like cytokines secreted by GH that promote nerve, bone, and muscle

growth and are involved protein metabolism. IGF-I mediates thymus lymphocyte

(T-cell) proliferation in the immune system (see IGF-I below). IGF's are also

thought to modulate steroid hormone actions in the endometrium (Rutanen EM,

2000). Zinc appears to modulate serum testosterone produced by the leydig

cells of testes, and is necessary for spermatogenesis. In one study by Prasad,

cellular zinc concentrations significantly reflected serum testosterone levels

in healthy men. Men with lower cellular zinc levels (and marginal dietary

deficiencies) had correspondingly lower testosterone levels (Prasad AS, 1996, &

1983). Prolactin requires zinc to stimulate lactation and breast tissue

growth. Zinc is also an important cofactor involved in the metabolism of

neurotransmitters, fatty acids, prostaglandins, and melatonin, and indirectly

affects dopamine metabolism (Arnold LE, 2000). The thyroid gland appears to

depend on zinc concentrations in blood cells for proper function as well

(Ganapathy S, 1999).

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