Co-existence and origin of peptidergic and adrenergic nerves in the guinea pig uterus. Retrograde tracing and immunocytochemistry, effects of chemical sympathectomy, capsaicin treatment and pregnancy.

The occurrence and distribution of peptidergic nerves in the guinea pig uterus was studied by means of immunocytochemistry using numerous neuropeptide anti-sera. Neuropeptide Y (NPY)-immunoreactive (IR) nerves were the most abundant, whereas substance P (SP)-, calcitonin gene-related peptide (CGRP)-, and neurokinin A (NKA)-IR nerves were less frequent, and peptide histidine isoleucine (PHI)-IR nerves were the most sparse. Chemical sympathectomy by means of 6-hydroxydopamine, and capsaicin treatment revealed the division of the peptidergic nerves into three separate populations: (1) NPY-IR nerves, which co-existed with adrenergic nerves, (2) SP-, CGRP- and NKA-IR nerves, which mutually co-existed, and (3) PHI-IR nerves. Parallel-running adrenergic/NPY-IR and SP-IR nerves could be found with very similar although not completely identical morphological appearance. Paracervical ganglia contained neurotensin- and dynorphin A-IR cells bodies in addition to cell bodies with immunoreactivities similar to those in prevertebral ganglia. Combined retrograde tracing with True blue and immunocytochemistry showed that the adrenergic and NPY-IR uterine nerves originate in paracervical and prevertebral ganglia. In the prevertebral ganglia the cellular origin was the same for adrenergic and NPY-IR nerves. In contrast, SP-, CGRP-, and NKA-IR nerves originated in dorsal root ganglia. At full-term pregnancy all the neuropeptide immunoreactivities had vanished, probably reflecting a fetus-induced general nerve degeneration.