SUMMARY AND CONCLUSIONS
Marijuana and its active component THC affect multiple
endocrine systems. A suppressive effect is seen on
the reproductive hormones, prolactin, growth hormone,
and the thyroid axis, while the HPA axis is activated.
These effects are mediated through CB1 receptor
activation in the hypothalamus, which directly or indirectly
modulates anterior pituitary function. Many of
the responses observed, however, are lost with chronic
administration, which is likely due to the development
of tolerance. Studies in humans have had inconsistent
results that may reflect differences in study design, the
hormonal milieu (e.g., stage in menstrual cycle), or the
development of tolerance. Long-term effects on the various
endocrine systems have not been clearly demonstrated,
and clinical consequences, if present, are likely
to be subtle.