FoundationalConceptsNeuroscience

Vasopressin, from Latin vaso = vessel, and pressare = to act on, to

push on.

OH

Tyr

oO

H O

aN N

Cys H

. HN
S
| Tle
S
Oo HN Oo
H
N N
O 4 N Gin
ae N Oo Oo Oo

HON (^2) Gly N H oO Cys ° Asn i
(^7) QO Pro NH2 de
Leu
Figure 21.3. Molecular structure of oxytocin, with the nine amino acids indi-
cated by their three-letter abbreviations. A disulfide (S-S) bond connects the
two cysteines (Cys), resulting in a ring structure in part of the molecule.
In addition to these effects as hormones, oxytocin and vasopressin
act at sites in the brain—G-protein-coupled receptors that specifically
respond to either one or the other. Peptides released from the hypo-
thalamus-pituitary into the blood do not reenter the brain because of
the blood-brain barrier. However, hypothalamic neurons also release