  Exclusive photoproduction of vector mesons in the perturbative two-gluon
exchange formalism depends significantly on nucleon and nuclear gluon
distributions. In the present study we calculate total cross sections and
rapidity distributions of $J/\psi(1s)$, $\psi(2s)$, $\Upsilon(1s)$,
$\Upsilon(2s)$, and $\Upsilon(3s)$ in ultraperipheral proton-lead (pPb) and
lead-lead (PbPb) collisions at the CERN Large Hadron Collider (LHC) at
$\sqrt{s_{_{NN}}}=5$ TeV and $\sqrt{s_{_{NN}}}=2.76$ TeV respectively. Effects
of gluon shadowing are investigated and potentials for constraining nuclear
gluon modifications are discussed.
