Immunocytochemical Localization of Luteinizing Hormone-Releasing Hormone in Male and Female Rat Brains

Shivers, Brenda D.; Harlan, Richard E.; Morrell, Joan I.; Pfaff, Donald W.

doi:10.1159/000123522

Cited by 191 publications

(52 citation statements)

References 19 publications

(36 reference statements)

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“…These numbers are in the range of the total expected for rodents of this size, and suggest that a large proportion of total GnRH neurons were immunoreactive in this study. Total GnRH cell numbers range from 300 to 400 in Djungarian hamsters (41), 650 to 750 in Syrian hamsters (20), and 500 to 1,300 in the rat (35,40). Thus our results are consistent with the hypothesis that NR have higher total numbers of GnRH neurons, which results in a higher number of cells producing mature hormone in NR than in RI at all times, and permits reproductive activity even if some suppression of GnRH secretion occurs in SD.…”

Section: Discussionsupporting

confidence: 87%

Response to selection for photoperiod responsiveness on the density and location of mature GnRH-releasing neurons

Avigdor¹,

Sullivan²,

Heideman³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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-Natural variation in neuroendocrine traits is poorly understood, despite the importance of variation in brain function and evolution. Most rodents in the temperate zones inhibit reproduction and other nonessential functions in short winter photoperiods, but some have little or no reproductive response. We tested whether genetic variability in reproductive seasonality is related to individual differences in the neuronal function of the gonadotropin-releasing hormone network, as assessed by the number and location of mature gonadotropin-releasing hormonesecreting neurons under inhibitory and excitatory photoperiods. The experiments used lines of Peromyscus leucopus previously developed by selection from a wild population. One line contained individuals reproductively inhibited by short photoperiod, and the other line contained individuals nonresponsive to short photoperiod. Expression of mature gonadotropin-releasing hormone (GnRH) immunoreactivity in the brain was detected using SMI-41 antibody in the single-labeled avidin-biotin-peroxidase-complex method. Nonresponsive mice had 50% more immunoreactive GnRH neurons than reproductively inhibited mice in both short-and long-day photoperiods. The greatest differences were in the anterior hypothalamus and preoptic areas. In contrast, we detected no significant within-lines differences in the number or location of immunoreactive GnRH neurons between photoperiod treatments. Our data indicate that high levels of genetic variation in a single wild population for a specific neuronal trait are related to phenotypic variation in a life history trait, i.e., winter reproduction. Variation in GnRH neuronal activity may underlie some of the natural reproductive and life history variation observed in wild populations of P. leucopus. Similar genetic variation in neuronal traits may be present in humans and other species. genetic variation; artificial selection; seasonality; evolutionary physiology; brain variation; gonadotropin-releasing hormone WITHIN-POPULATION GENETIC VARIATION regulating the abundance, location, and connections of neurons must contribute to evolution of brain function. Similarly, natural genetic variation in neuronal traits is presumably responsible for some proportion of intraspecific functional variation in vertebrates. Because neural circuitry regulates reproductive physiology and behavior, neural variation is likely to explain some unknown proportion of life history variation within as well as among species. At present, almost nothing is known about natural levels of genetically based neuroendocrine physiological variation related to life history variation within species of mammals. The physiological link between genes and life history patterns is important because genes must act on life history traits through physiological mechanisms, and thus physiological variation may shape or constrain life history evolution (16). Understanding natural neuroendocrine variation related to life history traits might help us learn how rapidly brains adapt to current cha...

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Section: Discussionsupporting

confidence: 87%

Response to selection for photoperiod responsiveness on the density and location of mature GnRH-releasing neurons

Avigdor¹,

Sullivan²,

Heideman³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Dynamic acute increases in plasma LH have been reported to be accompanied by depletion of LHRH within neuronal perikarya in rats, 6 days after ovariectomy ( I , 8,10) and on the morning of estrus in intact cycling rats ( I 1, 12). We have correlated these depletions with an increase in protein-synthesizing organelles, particularly Golgi complexes, in remaining populations of immunoreactive cells in both ovariectomized females (1) and intact cycling females ( 1 3).…”

Section: Discussionmentioning

confidence: 99%

Vaginocervical Stimulation of Ferrets Induces Release of Luteinizing Hormone‐Releasing Hormone

Bibeau

Tobet

Anthony

et al. 1991

J Neuroendocrinology

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Vaginocervical stimulation of ovariectomized estradiol-primed ferrets (which a r e reflex ovulators) with a glass rod in the presence of a neck-gripping male induced an increase in plasma luteinizing hormone (LH) from undetectable levels (20.50 nglml) before Stimulation, to 2.4k0.43 ng/ml 75 min after stimulation (stimulated females). Forty-eight h after stimulation plasma LH returned to baseline levels (post-stimulated females). A significant decrease in the number of perikarya containing LH-releasing hormone (LHRH), detected by immunocytochemistry, was associated with the increase in plasma LH following stimulation. Approximately one half of the number of immunoreactive LHRH neurons (243+27) were detected in t h e forebrain of stimulated females, compared to those detected in the forebrain of post-stimulated animals (436+88) using antiserum AR 744. Equivalent results were obtained with a different antiserum (RM 1076) capable of detecting the extended decapeptide, or precursor, as well as partially or fully processed decapeptide.We conclude that controlled vaginocervical stimulation of female ferrets evokes the release of LHRH as well as LH, depleting approximately 50% of the LHRH perikarya of detectable LHRH. Additionally, electron microscopy of LHRH perikarya of stimulated females revealed more Golgi complexeslcell compared to baseline females. W e propose that vaginocervical stimulation also augments the processing of extended precursor forms of LHRH to generate the decapeptide.The neural, chemical and environmental stimuli that regulate the tiniilig of ovulation ultimately transfer information to hypothalanile ncurocndocrine cells, and thereby alter the release of luteinizing hormone-releasing hormone (LHRH). The mechanisms whcrcby these stimuli interact to induce release of LHRH are un6 Tiown. Further. these stimuli may also be important in regulating Lhe biosynthesis or processing of preproLHRH.U u havc recently demonstrated a progressive augmentation in Proloin synthesizing organelles (i.e. rough endoplasmic reticulum, Golgi apparatus and associated vesicles) within LHRH perikarya of civariectomized rats. These morphological alterations within Lf~1ftf-I perikarya occurred as plasma LH levels escalated subxc]clcnt to ovariectomy. Accompanying thesc intraneuronal a h ;Ilions, we observed modifications in synaptic profiles in the net11 Opil surrounding the LHRH perikarya (1). The increases in synaptic profiles also correlated with elevations of plasma LH fOlic)wing ovariectomy in the rat. These findings are consistent With the hypothesis that the signals mediating LHRH release ma!. 4so mediate synthesis/processing of LHRH precursor, generatill! physiologically active decapeptide. -~ ~~In this study we utilized an induced ovulator, the ferret (2-4), to examine alterations that occur within LHRH neurons in response to stimulation leading to elevated plasma LH levels. Carroll and associates ( 5 ) have established that penile intromission is the stimulus that is necessary to induce ovulation in ferrets;...

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“…The somal area of 50-75 neurons (approximately 10-15 per section) was measured using NIH Image Analysis software. The number of immunoreactive fibers in a section in the middle of the POA was quantified using the method of Shivers et al (1983). Briefly, the section was aligned under high magnification and overlaid with an ocular grid and the number of intersections of immunoreactive fibers with grid segments was used as an estimate of immunoreactive fiber numbers.…”

Section: Data Collection and Statistical Analysismentioning

confidence: 99%

Changes in Brain Gonadotropin-Releasing Hormone- and Vasoactive Intestinal Polypeptide-like Immunoreactivity Accompanying Reestablishment of Photosensitivity in Male Dark-Eyed Juncos (Junco hyemalis)

Deviche

Saldanha

Silver

2000

General and Comparative Endocrinology

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In seasonally breeding, photoperiodic birds, the development of photorefractoriness is associated with decreased brain expression of gonadotropin-releasing hormone-like immunoreactivity (GnRH-li ir) and increased expression of vasoactive intestinal polypeptide-like immunoreactivity (VIP-li ir). Dissipation of photorefractoriness and reestablishment of photosensitivity are associated with increased GnRH-li ir brain production, but concurrent changes in VIP-li ir expression have not been investigated. To address this question, we compared the expression of VIP-li ir in the infundibulum (INF) of adult male dark-eyed juncos (Junco hyemalis) that were made photorefractory (PR) by prolonged exposure to long days with that of birds that were not photostimulated (PS), but had regained photosensitivity by exposure to short days for 5 (shortterm-PS, ST-PS) or 13 (long-term-PS, LT-PS) consecutive months. Photosensitive males had smaller INF VIP-li ir cell bodies than PR males, but the numbers of INF VIP-li ir cells were independent of photoperiodic condition. Changes in infundibular VIP-li ir were correlated with changes in preoptic area (POA) GnRH-li expression. Specifically, photosensitive males had more and larger POA GnRH-li ir cells and more GnRH-li ir fibers in this region than PR males. Further, LT-PS males had more GnRH-li ir POA fibers and larger testes than ST-PS juncos. Thus, induction of photorefractoriness is associated with increased VIP and decreased GnRH brain expression whereas dissipation of photorefractoriness concurs with decreased VIP and increased GnRH brain expression. These results suggest a physiological role for VIP in the control of changes in GnRH expression as a function of the photosensitive condition. KeywordsGnRH; VIP; reproduction; prolactin; seasonality; photoperiodism; photosensitivity; photorefractoriness; immunocytochemistry; preoptic area; infundibulum Most birds breeding at middle and high latitudes reproduce only during spring and early summer, when environmental conditions are the most favorable to successful raising of (Lack, 1968;Perrins, 1970). In these species and as originally demonstrated experimentally in dark-eyed juncos (Junco hyemalis;Rowan, 1925), photoperiod plays an essential role in the control of seasonal changes of reproductive system activity. Exposing photosensitive birds to daylength longer than approximately 12 h (defined as long days, LD), as is naturally the case during the spring, stimulates the release of hypothalamic gonadotropin-releasing hormone (GnRH) and pituitary-luteinizing hormone (LH) and follicle-stimulating hormone (FSH; Lewis and Farner, 1973;Wingfield et al., 1980;Dawson and Goldsmith, 1983;Fehrer et al., 1985;Wilson, 1985;Foster et al., 1987;McNaughton et al., 1995;Meddle and Follett, 1997). These hormones in turn induce gonadal development and the secretion of gonadal hormones that control many behavioral changes associated with the breeding period as well as the development of secondary sexual characteristics (Balthazart et al., 1979;...

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Immunocytochemical Localization of Luteinizing Hormone-Releasing Hormone in Male and Female Rat Brains

Cited by 191 publications

References 19 publications

Response to selection for photoperiod responsiveness on the density and location of mature GnRH-releasing neurons

Response to selection for photoperiod responsiveness on the density and location of mature GnRH-releasing neurons

Vaginocervical Stimulation of Ferrets Induces Release of Luteinizing Hormone‐Releasing Hormone

Changes in Brain Gonadotropin-Releasing Hormone- and Vasoactive Intestinal Polypeptide-like Immunoreactivity Accompanying Reestablishment of Photosensitivity in Male Dark-Eyed Juncos (Junco hyemalis)

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