Neuropeptide Y and tyrosine hydroxylase mRNA levels in the locus coeruleus show similar increases after reserpine treatment

In situ hybridisation histochemistry was used to study the effect of intra-peritoneal reserpine administration on messenger RNA (mRNA) levels in the locus coeruleus (LC) of the rat. 43h after injection, levels of mRNA encoding tyrosine hydroxylase (TH) and neuropeptide Y (NPY) in the LC increased to ∼250% of control values (p < 0.05). The level of beta-tubulin mRNA was unaffected by reserpine administration. The similar and selective increase in TH and NPY mRNA in the LC following reserpine administration suggests that NPY may play a role in the neurotransmitter function of this catecholaminergic nucleus.