Effects of intra-PAG infusion of ovine CRF on defensive behaviors in Swiss-Webster mice

The midbrain dorsal periaqueductal gray (DPAG) is part of the brain defensive system involved in active defense reactions to threatening stimuli. Corticotrophin releasing factor (CRF) is a peptidergic neurotransmitter that has been strongly implicated in the control of both behavioral and endocrine responses to threat and stress. We investigated the effect of the nonspecific CRF receptor agonist, ovine CRF (oCRF), injected into the DPAG of mice, in two predator-stress situations, the mouse defense test battery (MDTB), and the rat exposure test (RET). In the MDTB, oCRF weakly modified defensive behaviors in mice confronted by the predator (rat); e.g. it increased avoidance distance when the rat was approached and escape attempts (jump escapes) in forced contact. In the RET, drug infusion enhanced duration in the chamber while reduced tunnel and surface time, and reduced contact with the screen which divides the subject and the predator. oCRF also reduced both frequency and duration of risk assessment (stretch attend posture: SAP) in the tunnel and tended to increase freezing. These findings suggest that patterns of defensiveness in response to low intensity threat (RET) are more sensitive to intra-DPAG oCRF than those triggered by high intensity threats (MDTB). Our data indicate that CRF systems may be functionally involved in unconditioned defenses to a predator, consonant with a role for DPAG CRF systems in the regulation of emotionality. (c) 2006 Elsevier B.V. All rights reserved.

Temperatura e osmocondicionamento na germinação de sementes de Urochloa brizantha (STAPF) Webster cv. Basilisk

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Regeneração natural de um fragmento de cerrado degradado com a formação de pastagens de braquiária (Urochloa decumbens (Stapf) R. D. Webster)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Priming and temperature limits for germination of dispersal units of Urochloa brizantha (Stapf) Webster cv. basilisk

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Letter from William Croswell to Redford Webster, 1820 February 24

Draft of a one-page letter declining a request by Webster.

Letters from William Croswell to Redford Webster, 1821 January

This folder contains drafts of two one-page letters, dated January 5, 1821, and January 9, 1821, regarding financial assistance.

Letter from William Croswell to Dr. Webster, 1823 September 16

Draft of a letter regarding aid from the Pemberton Fund.

Subjects suggested by John Webster, 1826 July

A handwritten letter with suggested subjects from John White Webster, a lecturer of chemistry, mineralogy, and geology at the Harvard Medical College from 1824 until 1827, when he was appointed the Erving Professor of Chemistry (1827-1850).

Record book of the settlement of the estate of Pelatiah Webster, 1795-1799

Manuscript record of the disposition of the estate of Pelatiah Webster, kept by his daughter and executrix, Ruth Webster Perit. Begins with a statement of Pelatiah Webster's death on 2 September 1795, followed by a certified copy of his will. Record also includes letter of administration; list of charges, credits, and debts against the estate; funeral costs; descriptions of properties; income from rents, etc.