The Journal of Neuroscience, July 15, 1998, 18(14):5477-5489
Hypothalamic Neurons Preferentially Respond to Female Nest Coo
Stimulation: Demonstration of Direct Acoustic Stimulation of
Luteinizing Hormone Release
Mei-Fang
Cheng1,
Jing
Pian
Peng1, and
Patricia
Johnson2
1 Department of Psychology, Biopsychology Program,
Rutgers University, Newark, New Jersey 07102, and
2 Department of Animal Science, Cornell University, Ithaca,
New York 14853
Avian vocalizations are generally understood to play a pivotal role
in reproductive functions. The role of the hypothalamus in gonadotropin
release in higher vertebrates including birds is well established. To
date, however, a direct linkage between the neuronal processing of
vocal input and the contingent luteinizing hormone (LH) response has
not been demonstrated. In this study, using female ring doves, we
recorded neuronal activity from hypothalamic nuclei that, as we have
shown previously, receive acoustic inputs from the auditory thalamic
relay. Concurrently with recording single-unit responses to stimulation
with species-specific coo vocalizations, we sampled LH levels in blood
from the pituitary veins. LH concentration in the plasma was
significantly elevated in birds hearing species-typical coos but not in
birds exposed to experimentally altered coos or white noise or in birds
that received no vocal stimulation. We found two types of neurons in the preoptic and anterior hypothalamus that selectively responded to
the female nest coo: excitatory units and inhibitory units. Among the
excitatory neurons are units characterized by two bursts separated by a
period of slow spiking or complete silence, in a pattern approximately
corresponding temporally to the two-note coo. We designate them as
female-nest-coo-specific units. Most neurons in the posterior
hypothalamus were nonselective in their response. Female nest coo and
male nest coo stimulation evoked an equal magnitude of discharge
changes from responsive units in the preoptic-anterior hypothalamic
area. We found, however, that the LH increment was three times greater
for birds hearing female nest coos than for birds hearing male nest
coos. These observations suggest that feature-detecting neurons such as
the female-nest-coo-specific units are involved in
gonadotropin-releasing hormone output. The present findings are
consistent with the well established behavioral evidence that female
nest coos mediate ovarian growth.
Key words:
vocalization; sound stimulation of endocrine
response; hypothalamus; auditory processing; GnRH; call-specific
neuronal discharge
Copyright © 1998 Society for Neuroscience 0270-6474/98/18145477-13$05.00/0
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