Enkephalin-like immunoreactivity in the chick brainstem: possible relation to the cochlear efferent system

• Published in: Hearing research Vol. 87; no. 1; pp. 69 - 83
• Main Authors: Code, R.A., Carr, C.E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.1995; Elsevier
• Subjects: Animals; Biological and medical sciences; Brain Stem - chemistry; Brain Stem - cytology; Cell Size - drug effects; Cell Size - physiology; ChAT-immunoreactivity; Chickens - anatomy & histology; Choline O-Acetyltransferase - analysis; Cochlea - cytology; Cochlea - drug effects; Cochlear efferent neuron; Colchicine - administration & dosage; Colchicine - pharmacology; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Enkephalin, Leucine - analysis; Enkephalins - analysis; Facial Nerve - chemistry; Facial Nerve - cytology; Fundamental and applied biological sciences. Psychology; Immunohistochemistry; Lateral lemniscal nuclei; Neurons, Efferent - chemistry; Neurons, Efferent - cytology; Olivary Nucleus - chemistry; Olivary Nucleus - drug effects; Superior olivary nucleus; Trigeminal Nuclei - chemistry; Trigeminal Nuclei - cytology; Vagus Nerve - chemistry; Vagus Nerve - cytology; Vertebrates: nervous system and sense organs; LoC; TD V; TV; MLF; VIId; Ta; ChAT-immunoreactivity; Mn V; ICo; SCd; GCt; IC; Imc; MLd; IO; SCv; IV; Rgc; IX–X; RST; NA; VI; RPgc; SLu; NL; RP; NM; BC; N. VII; PBv; Superior olivary nucleus; FLM; L-Enk-LI; RPO; Rx V M; R; N. VI; S; VeD; ChAT; M-Enk-LI; SO; VeL; MOC; LLd; Rpgl; VeS; LLi; VIIv; Lateral lemniscal nuclei; RPaM; nPr V; N. V; LC; LLv; Cochlear efferent neuron; PL; Ipc; PM; Acyltransferases; Enzyme; Transferases; Central nervous system; Enkephalin; Choline O-acetyltransferase; Neuropeptide; Opioid peptide; Inner ear; Vertebrata; Peptidergic neuron; Immunoreactive form; Cochlea; Auditory pathway; Chicken; Aves; Olivocochlear bundle; Brain (vertebrata)
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(95)00080-N

Mammalian lateral olivocochlear (LOC) neurons that are immunoreactive for choline acetyltransferase (ChAT) are also immunoreactive for enkephalin (Enk). To determine whether cochlear efferent neurons in birds might also contain Enk-like immunoreactivity (Enk-LI), we studied the auditory brainstem of the domestic chicken using antisera to ChAT, leucine-enkephalin (L-Enk) and methionine-enkephalin (M-Enk). Enk-LI terminals are found around, but not within, the superior olivary nucleus (SO) and the nucleus of the lateral lemniscus, pars intermedia (LLi). A moderate concentration of Enk-LI terminals is found ventromedial to the ventral facial nucleus (VIIv) where the ventrolateral group of ChAT-I cochlear efferent neurons is located. After colchicine injections into the lateral ventricle, a population of intensely stained Enk-LI perikarya was found in the nucleus of the lateral lemniscus, pars ventralis (LLv) with scattered cells in the LLi and the nucleus subceruleus ventralis (SCv). The distribution of Enk-LI and ChAT-I somata, however, never overlapped, even in adjacent sections. Thus, in the chick, Enk-LI perikarya are not distributed in areas where cochlear efferent neurons are found. Instead, a dense concentration of Enk-I terminals can be found in areas containing ChAT-I cochlear efferent neurons. The source of these enkephalinergic terminals may be a population of Enk-LI cells in the LLv.