Efferent connections of the “olfactostriatum”: A specialized vomeronasal structure within the basal ganglia of snakes

Martı́nez-Marcos, Alino; Úbeda-Bañón, Isabel; Lanuza, Enrique; Halpern, Mimi

doi:10.1016/j.jchemneu.2005.02.001

Cited by 16 publications

(3 citation statements)

References 38 publications

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“…Stained tissue was examined using an Olympus BX40 microscope with a QIClick digital camera and QImaging software (QImaging). Locations of GnRH‐immunoreactive (ir) cells were mapped onto standard anatomical brain sections adapted from Smith et al (1997), Martinez‐Marcos, et al, (2001; 2005), and Lutterschmidt and Maine (2014). We quantified manually the total number of GnRH‐immunoreactive (ir) cells in every tissue section throughout the region of interest following the methods of Lutterschmidt and Wilczynski (2012).…”

Section: Methodsmentioning

confidence: 99%

Trans‐seasonal activation of the neuroendocrine reproductive axis: Low‐temperature winter dormancy modulates gonadotropin‐releasing hormone neurons in garter snakes

2021

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All animals use external cues from the environment to accurately time life‐history events. How the brain decodes environmental stimuli to effect changes in physiology and behavior, however, is poorly understood, particularly with regard to supplementary environmental cues such as temperature. We asked if low‐temperature dormancy alters the synthesis and/or release of gonadotropin‐releasing hormone (GnRH). We used the well‐studied red‐sided garter snake (Thamnophis sirtalis) for this study, as low‐temperature exposure is both necessary and sufficient to induce reproduction in northern populations of this species. Snakes were collected from the field and hibernated at 4°C or 10°C in complete darkness for up to 16 weeks. In males, increasing duration of low‐temperature dormancy significantly increased GnRH‐immunoreactive cell number and GnRH soma size (a proxy for relative cell activity) in the forebrain. These changes mirrored those in male reproductive behavior (reported previously) and plasma androgen concentrations. The changes in GnRH cell area observed in males were specific to the neuroendocrine population of cells in the medial preoptic area; soma size in the rostral GnRH cells did not change. Finally, temperature‐induced changes in GnRH were sexually dimorphic: neither hibernation temperature nor the duration of winter dormancy significantly modulated GnRH cell number or soma size in females, despite the fact that plasma estradiol and corticosterone increased significantly in response to both. These data demonstrate that the neuroendocrine GnRH system is sensitive to environmental temperature and suggest that GnRH neurons play a conserved but trans‐seasonal role in mediating changes in reproductive physiology and behavior in dissociated breeders.

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Section: Methodsmentioning

confidence: 99%

Trans‐seasonal activation of the neuroendocrine reproductive axis: Low‐temperature winter dormancy modulates gonadotropin‐releasing hormone neurons in garter snakes

2021

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“…Stained tissue was examined using an Olympus BX40 microscope with a QIClick digital camera and QImaging software (QImaging, Surrey, Bristish Columbia, Canada). Locations of BrdU-immunoreactive (ir) cells were mapped onto standard anatomical brain sections adapted from Krohmer et al ( 2010 ) and Martínez-Marcos et al ( 2001 , 2005 ). Newly proliferated, BrdU-ir cells were regionally distributed in the adult red-sided garter snake brain as shown in Figure 1 .…”

Section: Methodsmentioning

confidence: 99%

Sexually Dimorphic Patterns of Cell Proliferation in the Brain Are Linked to Seasonal Life-History Transitions in Red-Sided Garter Snakes

et al. 2018

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Seasonal rhythms in physiology and behavior are widespread across diverse taxonomic groups and may be mediated by seasonal changes in neurogenesis, including cell proliferation, migration, and differentiation. We examined if cell proliferation in the brain is associated with the seasonal life-history transition from spring breeding to migration and summer foraging in a free-ranging population of red-sided garter snakes (Thamnophis sirtalis) in Manitoba, Canada. We used the thymidine analog 5-bromo-2′-deoxyuridine (BrdU) to label newly proliferated cells within the brain of adult snakes collected from the den during the mating season or from a road located along their migratory route. To assess rates of cell migration, we further categorized BrdU-labeled cells according to their location within the ventricular zone or parenchymal region of the nucleus sphericus (homolog of the amygdala), preoptic area/hypothalamus, septal nucleus, and cortex (homolog of the hippocampus). We found that cell proliferation and cell migration varied significantly with sex, the migratory status of snakes, and reproductive behavior in males. In most regions of interest, patterns of cell proliferation were sexually dimorphic, with males having significantly more BrdU-labeled cells than females prior to migration. However, during the initial stages of migration, females exhibited a significant increase in cell proliferation within the nucleus sphericus, hypothalamus, and septal nucleus, but not in any subregion of the cortex. In contrast, migrating males exhibited a significant increase in cell proliferation within the medial cortex but no other brain region. Because it is unlikely that the medial cortex plays a sexually dimorphic role in spatial memory during spring migration, we speculate that cell proliferation within the male medial cortex is associated with regulation of the hypothalamus-pituitary-adrenal axis. Finally, the only brain region where cell migration into the parenchymal region varied significantly with sex or migratory status was the hypothalamus. These results suggest that the migration of newly proliferated cells and/or the continued division of undifferentiated cells are activated earlier or to a greater extent in the hypothalamus. Our data suggest that sexually dimorphic changes in cell proliferation and cell migration in the adult brain may mediate sex differences in the timing of seasonal life-history transitions.

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“…The next stage in this project was challenging; it required counting and recording all of the NPY-ir cells in three brain regions, the cortex, nucleus sphericus, and pore-optic area (POA)/hypothalamus, under the microscope after imaging each section. The brain regions were mapped according to anatomical brain sections adapted from (Martinez-Marcos et al, 2001, Martinez-Marcos, 2005, and Khromer et al, 2010) (See Figure 2). Each region had to be counted by a single individual to ensure consistency.…”

Section: Richards-4mentioning

confidence: 99%

Perseverance, Adaptation, and the Quest for a New Morality: Anarchism in Spain, 1868-2005

Nelson¹

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Efferent connections of the “olfactostriatum”: A specialized vomeronasal structure within the basal ganglia of snakes

Cited by 16 publications

References 38 publications

Trans‐seasonal activation of the neuroendocrine reproductive axis: Low‐temperature winter dormancy modulates gonadotropin‐releasing hormone neurons in garter snakes

Trans‐seasonal activation of the neuroendocrine reproductive axis: Low‐temperature winter dormancy modulates gonadotropin‐releasing hormone neurons in garter snakes

Sexually Dimorphic Patterns of Cell Proliferation in the Brain Are Linked to Seasonal Life-History Transitions in Red-Sided Garter Snakes

Perseverance, Adaptation, and the Quest for a New Morality: Anarchism in Spain, 1868-2005

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