a-do-it-yourself-system-for-scheduled-feeding-laboratory-rodents

A Do-it-yourself System for Scheduled Feeding of Laboratory Rodents in Their Home Cage

Intermittent fasting and research surrounding the influence of timed caloric restriction on body weight regulation and aging outcomes are trending, both ...

University of Massachusetts

Successful reproduction in female mammals is precisely timed and must be able to withstand the metabolic demand of pregnancy and lactation. We show that kisspeptin-expressing neurons in the arcuate hypothalamus (Kiss1) of female mice control the daily timing of food intake, along with the circadian regulation of locomotor activity, sleep, and core body temperature. Toxin-induced silencing of Kiss1 neurons shifts wakefulness and food consumption to the light phase and induces weight gain. Toxin-silenced mice are less physically active and have attenuated temperature rhythms. Because the rhythm of the master clock in the suprachiasmatic nucleus (SCN) appears to be intact, we hypothesize that Kiss1 neurons signal to neurons downstream of the master clock to modulate the output of the SCN. We conclude that, in addition to their well-established role in regulating fertility, Kiss1 neurons are a critical component of the hypothalamic circadian oscillator network that times overt rhythms of physiology and behavior.

Kisspeptin Neurons in the Arcuate Nucleus of the Hypothalamus Orchestrate Circadian Rhythms and Metabolism.

In hungry animals, neuropeptide Y (NPY) neurones in the arcuate nucleus (ArcN) are activated to suppress energy expenditure, in part by decreasing brown adipose tissue sympathetic nerve activity (BAT SNA); however, the NPY receptor subtype and brain neurocircuitry are unclear. In the present study, we investigated the inhibition of BAT SNA by exogenous and endogenous NPY via binding to Y1 receptors (NPY1R) in the hypothalamic paraventricular nucleus (PVN) and dorsomedial hypothalamus (DMH), in anaesthetised male rats. Downstream projections of PVN/DMH NPY1R-expressing neurones were identified using male Npy1r-cre mice and localised unilateral DMH or PVN injections of an adeno-associated virus, which allows for the cre-dependent expression of a fluorescent protein (mCherry) in the cell bodies, axon fibres and nerve terminals of NPY1R-containing neurones. Nanoinjections of NPY into the DMH of cooled rats decreased BAT SNA, as well as mean arterial pressure (MAP) and heart rate (HR), and these responses were reversed by subsequent injection of the selective NPY1R antagonist, BIBO3304. In warmed rats, with little to no BAT SNA, bilateral nanoinjections of BIBO3304 into the DMH or PVN increased BAT SNA, MAP and HR. DMH NPY1R-expressing neurones projected heavily to the raphe pallidus (RPa), which houses BAT presympathetic neurones, as well as the PVN. In anaesthetised mice, DMH BIBO3304 increased splanchnic SNA, MAP and HR, all of which were reversed by nonselective blockade of the PVN with muscimol, suggesting that DMH-to-PVN connections are involved in this DMH BIBO3304 disinhibition. PVN Y1R expressing neurones also projected to the RPa, as well as to the nucleus tractus solitarius. We conclude that NPY tonically released in the DMH and PVN suppresses BAT SNA, MAP and HR via Y1R. Downstream neuropathways for BAT SNA may utilise direct projections to the RPa. Release of tonic NPY inhibition of BAT SNA may contribute to feeding- and diet-induced thermogenesis.

Neuropeptide Y suppresses thermogenic and cardiovascular sympathetic nerve activity via Y1 receptors in the paraventricular nucleus and dorsomedial hypothalamus.

Complex social behaviors are emergent properties of the brain's interconnected and overlapping neural networks. Questions aimed at understanding how brain circuits produce specific and appropriate behaviors have changed over the past half century, shifting from studies of gross anatomical and behavioral associations, to manipulating and monitoring precisely targeted cell types. This technical progression has enabled increasingly deep insights into the regulation of perception and behavior with remarkable precision. The capacity of reductionist approaches to identify the function of isolated circuits is undeniable but many behaviors require rapid integration of diverse inputs. This review examines progress toward understanding integrative social circuits and focuses on specific nodes of the social behavior network including the medial amygdala, ventromedial hypothalamus (VMH) and medial preoptic area of the hypothalamus (MPOA) as examples of broad integration between multiple interwoven brain circuits. Our understanding of mechanisms for producing social behavior has deepened in conjunction with advances in technologies for visualizing and manipulating specific neurons and, here, we consider emerging strategies to address brain circuit function in the context of integrative anatomy.

Article	Year
Kisspeptin Neurons in the Arcuate Nucleus of the Hypothalamus Orchestrate Circadian Rhythms and Metabolism. Current biology : CB\| PubMed ID: 30744968	2019
Neuropeptide Y suppresses thermogenic and cardiovascular sympathetic nerve activity via Y1 receptors in the paraventricular nucleus and dorsomedial hypothalamus. Journal of neuroendocrinology\| PubMed ID: 34235800	2021
From Reductionism Toward Integration: Understanding How Social Behavior Emerges From Integrated Circuits. Frontiers in integrative neuroscience\| PubMed ID: 35431824	2022

Stephanie L. Padilla

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