Strenuous exercise increases plasma melatonin, cortisol, and ?-endorphin concentrations. Furthermore, a relationship between endogenous opioids and melatonin has been proposed. We measured plasma melatonin, cortisol, and ?-endorphin in 46 subjects before and after a 28.5-mile high altitude race. Thirteen of the subjects received the orally active opioid antagonist naltrexone immediately before the race. The mean plasma melatonin, cortisol, and ?-endorphin levels were higher after the race than before it; the melatonin results were confirmed by gas chromatography-mass spectrometry assay of 12 subjects. Naltrexone had no effect on the increase in any of the three hormones. (via.)
This study was briefly mentioned in “DMT: The Spirit Molecule.” I happened to run across it and thought I’d tuck it away on the blog in case it ever comes up again for some reason.
A single injection of morphine to fight persistent pain in male rats is able to strongly reduce the hormone testosterone in the brain and plasma [...] The study, led by Anna Maria Aloisi, M.D., showed that opioids had “long lasting genomic effects in body areas which contribute to strong central and peripheral testosterone levels” including the brain, the liver and the testis.
The study showed increases in aromatase, an enzyme that is responsible for a key step in the biosynthesis of estrogen. The findings are particularly important since testosterone is the main substrate of aromatase, which is involved in the formation of estradiol. [...]
Opioid induced hypogonadism can cause health complications to which patients with pain can be overly susceptible, including chronic fatigue, loss of stamina, emotional and sexual disturbances, as well painful skeletal and muscular complications. [...]
“Until a few years ago this condition was completely unrecognized by physicians although some reports clearly showed it in many kinds of patients,” notes Dr. Aloisi. (via.)
I’m reading Susan Kuchinskas’ book The Chemistry of Connection, which despite having a pink cover with cute bunnies on it is not even remotely gender biased — she’s got a real strong focus on the actual scientific literature, and stacks of citations.. which is fantastic! At times she tries to “translate” the research into laymens terms, but then takes it back around to the technical. So far I’m very satisfied with it.
However, that’s entirely beside the point! Today’s blog post is actually, about the ventral pallidum, which she mentions on page 89.
I’ll quote the sentence that enticed this blog post:
Helen Fisher thinks that the same variations in vasopressin and oxytocin activity in the brain’s reward center and in the ventral pallidum, a structure that’s more active in long-term relationships, could also account for differences in “partner preference,” the early stage of courtship in which we identify that special someone we hope to make our own (Fisher, Aron, and Brown 2006).”
So, as I often do when I read something interesting about a brain region I’m unfamiliar with, I decided to peruse Eurekalert… Here’s a few of the goodies I found:
Rat’s ventral pallidum is activated more by sugar water than salt water, unless they’re salt deprived… under which circumstances the ventral pallidum is activated just as strongly as with sugar water. (via.)
“Scientists at Emory University have been able to increase bonding behavior in monogamous male prairie voles by transferring a receptor gene for the neuropeptide arginine vasopressin (AVP) into a particular region of the brain (the ventral pallidum).” [...] “Scientists previously have demonstrated that monogamy in voles, including the formation of pair bonds, is enhanced by vasopressin and that an antagonist for the vasopressin receptor can prevent the formation of pair bonding. Scientists also know that the distribution of the vasopressin receptor within certain regions of the brain is dramatically different between monogamous and non-monogamous species of voles. All monogamous vole species, even though they may be unrelated, have denser vasopressin receptor binding in the ventral pallidal region of the brain than do non-monogamous vole species.”(via.)
“[They] examined the distribution of two brain receptors in the ventral forebrain of monogamous prairie voles that have been previously tied to pair bond formation: oxytocin (OTR) and vasopressin V1a receptor (V1aR). Using receptor audiographic techniques, the scientists found that these receptors are confined to two of the brain’s reward centers, the nucleus accumbens and the ventral pallidum. V1aR receptors, which are thought to be activated in the male vole brain during pair bond formation, were confined largely to the ventral pallidum. OTR receptors, which play a crucial role in pair bond formation in females, were found mainly in the nucleus accumbens.” (via.)
“In the February 21 issue of the journal Science, the team will report that a small variation in the gene that encodes the enzyme called catechol-O-methyl transferase, or COMT, made a significant difference in the pain tolerance, and pain-related emotions and feelings, of healthy volunteers.”[...] The COMT protein is a sort of brain janitor, “cleaning up” the spaces between brain cells after chemicals called neurotransmitters finish sending signals between brain cells. Specifically, COMT metabolizes, or breaks down, the brain chemicals called dopamine and noradrenaline, also known as norepinephrine. Those with two copies of the val form of the gene make only powerful COMT that mops up dopamine rapidly. People with two copies of the met form of the gene make only poor COMT, and can’t “clean up” the dopamine in their brains very well. Those with one copy of each gene variety — the majority of people — make some of each kind of COMT, yielding a “normal” dopamine-metabolizing system. [...] And animal studies have shown that when the dopamine system is highly active, the brain reduces its production of other chemicals: the endogenous opioids, or so-called enkephalins. [...] Zubieta and his colleagues set out to see whether a person’s COMT genotype made a difference in their pain perception. They thought that perhaps those who metabolized dopamine very well because they had two val COMT genes would also be able to activate the brain’s painkilling system better than those with two copies of the met form of COMT. The results fit the predicted effect of COMT gene variation perfectly. Participants who had two copies of the met gene form could stand less of the painful injection than those with two copies of the val form of the gene, and their brains’ mu-opioid systems were less activated in many areas of the brain. [...] The differences between met/met and val/val participants in the activation of the mu-opioid system were most significant in the cingulate cortex, anterior thalamus, the thalamic pulvinar, and the basal ganglia, including the nucleus accumbens and ventral pallidum, and the amygdala. (via.)
“Our findings show that the brain areas activated when someone looks at a photo of their beloved only partially overlap with the brain regions associated with sexual arousal. Sex and romantic love involve quite different brain systems.” [...] Aron reported that, using functional magnetic resonance imaging (fMRI) and other measurements, he and his colleagues found support for their two major predictions: (1) early stage, intense romantic love is associated with subcortical reward regions rich with dopamine; and (2) romantic love engages brain systems associated with motivation to acquire a reward. [...] “Our data even may be relevant to some forms of autism,” Brown added. “Some people with autism don’t understand or experience any sort of emotional attachment or romantic love. I would speculate that autism involves an atypical development of the midbrain and basal ganglia reward systems.” [...] Another breakthrough, Brown noted, was that “we found several brain areas where the strength of neural activity changed with the length of the romance. Everyone knows that relationships are dynamic over time, but we are beginning to track what happens in the brain as a love relationship matures.” [...] Helen E. Fisher, a research anthropologist at Rutgers University, New Jersey, noted that not only did the brain change as romantic love endured, but that some of these changes were in regions associated with pair-bonding in prairie voles. The fMRI images showed more activity in the ventral pallidum portion of the basal ganglia in people with longer romantic relationships. (via.)
Disconnection studies have revealed that serial connections between basolateral amygdala, anterior cingulate cortex, nucleus accumbens, and ventral pallidum are involved in the exertion of effort and effort-related choice behavior (Floresco and Ghods-Sharifi, 2007; Farrar et al., 2008; Mingote et al., 2008; Hauber and Sommer, 2009). (via.)
Whew! I… may have broke a sweat. Anyhoo… This “ventral pallidum” area may be worth a google alert, I think.
Oh, before I forget… Make sure to check out Susan Kuchinskas’ websites: